Pollution, Toxicity and Carcinogenicity of Organic Dyes and their Catalytic Bio-Remediation

Sustainable green synthesis of high-performance Fe2O3@CeO2-pullulan nanocomposite for efficient dye removal, and antifungal applications

The escalating global environmental and microbial pollution necessitates the development of sustainable and efficient solutions, prompting the exploration of advanced nanomaterials. The current study reports the green synthesis of Fe2O3@CeO2 NPs using rosemary extract. Pullulan was incorporated as a mediating agent, resulting in Fe2O3@CeO2-pullulan NPs with improved dispersion and stability. The synthesized NPs were characterized using FTIR, UV-visible spectroscopy, zeta potential analysis, DLS, HR-TEM, SEM, and XRD. The phytochemical content in both NPs types contributed to antioxidant activity. Rosemary extract displayed the strongest antioxidant activity followed by Fe2O3@CeO2-pullulan NPs. Employing the artificial neural network successfully modeled and optimized the removal of MB, with a significant influence of both types of NPs. Both types of NPs demonstrated substantial activity against Candida albicans, with Fe2O3@CeO2-pullulan exhibiting a larger inhibition zone (35.67 ± 1.96 mm) compared to Fe2O3@CeO2 (33.33 ± 0.87 mm) and approved through FTIR and HR-TEM investigation. These findings suggest potential applications of the current NPs in various fields, including environmental remediation, and healthcare. Future research should elucidate the underlying mechanisms and explore specific other applications to maximize the benefits of the findings.

Catalytic reduction of aldehydic and nitro groups of nitro-benzaldehyde derivatives by silver nanoparticle-containing smart alginate-poly(N-isopropylacrylamide-methacrylic acid) microgels

Aromatic compounds containing aldehyde and nitro groups are very toxic to human health. Moreover, complete degradation of these compounds is not possible. Therefore, these compounds are converted into less toxic but more useful hydroxy-methyl aniline (HMA) derivatives. This conversion is performed using a suitable catalyst and a reducing agent. Therefore, alginate-poly(N-isopropylacrylamide-methacrylic acid) (AN-P(NIPAM-MAAc)) (AN-P(NM)) microgels were synthesized via a free radical precipitation polymerization (FRPP) method and were used as a micro-reactor for synthesis of silver (Ag) nanoparticles (NPs) into the polymeric network using in situ reduction methods. The synthesized AN-P(NM) microgels and Ag-AN-P(NM) hybrid microgels were characterized through SEM, FTIR, TEM, XRD, UV-vis spectroscopy, and EDX. Ag-AN-P(NM) exhibited temperature- and pH-responsive behavior as well as long-term stability of Ag nanoparticles in a polymeric network of AP(NM). Catalytic reduction of 4-nitrobenzaldehyde (4NBA) was evaluated under different conditions, such as different contents of Ag-AN-P(NM), 4NBA concentrations, temperatures, and concentrations of NaBH4. The Ag-AP(NM) hybrid microgels catalytically reduced 3-nitrobenzaldehyde (3NBA), 4NBA, and 3,5-dinitrobanzaldehyde (3,5DNBA) into their corresponding HA compounds in a water medium. The apparent rate constant (k ob) values for 3NBA, 4NBA, and 3,5DNBA were found to be 1.73 min-1, 1.48 min-1, and 1.19 min-1, respectively. Ag-AP(NM) exhibited outstanding catalytic efficiency, recyclability, and stability as well as retained its performance across multiple cycles.

Optimized Congo Red Dye Adsorption Using ZnCuCr-Based MOF for Sustainable Wastewater Treatment

This study presents the synthesis of a novel trimetallic ZnCuCr-TpIm metal-organic framework (MOF) via a solvothermal method, yielding cubic crystals of 300-500 nm. The integration of Zn, Cu, and Cr metal centers enhances the MOF's adsorption efficiency and structural stability, distinguishing it from conventional MOFs. The material achieves a high Congo red dye removal efficiency (96.5%) under optimal conditions: 40 mg adsorbent dosage, 55 °C, pH 6-7, and a 60 min contact time. Kinetic analysis reveals that the adsorption follows a pseudo-second-order model (R2 > 0.999), indicating chemisorption as the rate-limiting step, while equilibrium data align with the Langmuir isotherm model (R2 = 0.998), confirming a maximum adsorption capacity of 325 mg/g. FTIR and XRD analyses confirm strong interactions between the dye molecules and the MOF framework while preserving its crystalline structure. The ZnCuCr-TpIm MOF demonstrated exceptional stability, retaining 95% of its surface area after 72 h and maintaining over 90% adsorption efficiency after five reuse cycles, with minimal metal ion leaching (<1.2 ppm). The material also exhibited high resilience under varying pH, salinity, and simulated wastewater conditions, underscoring its potential for long-term and sustainable dye removal applications. These findings highlight the synergistic advantages of the trimetallic MOF, making it a promising candidate for efficient and stable wastewater treatment.

Isolation, structural characterization of (1 → 4), (1 → 6)-α-D-glucan from Dioscorea Alata and synthesis and catalytic activity studies of (1 → 4), (1 → 6)-α-D-glucan derived carbon dots

Herein, a straightforward, productive protocol was adopted for the synthesis of carbon dots (CDs) by a simple microwave-assisted technique from (1 → 4), (1 → 6)-α-D-glucan polysaccharide (DAPS). The isolation and structural characterization of (1 → 4), (1 → 6)-α-D-glucan from the aqueous extracting of the Diascorea Alata was described here. The photo-physical and morphological studies of the prepared high quantum yield (27.70 %) CDs were systematically characterized using different analytical techniques: TEM, DLS, XPS, XRD, FT-IR, TCSPC, EDX, Fluorescence and UV-vis spectroscopy. In our study the carbon dots (CDs) obtained are non-toxic, highly water-soluble, spherical-shaped negatively charged particles with an average diameter of 3.28 nm. The photo-catalytic activity of carbon dots (CDs) was tested under the sunlight for photo-degradation of crystal violet (CV), a pollutant organic dye. Carbon dots (CDs) showed outstanding results regarding the photo degradation of CV (achieving 99.9 % degradation within 8 min) under sunlight.

Accelerated Synergistic Photo-Fenton/Photocatalysis Reactions at Aqueous Interfaces

Photocatalysis and photo-Fenton oxidation are promising advanced oxidation technologies for water treatment. Nevertheless, their relatively slow kinetics largely limited their practical applications. Herein, we performed synergistic photocatalysis and photo-Fenton reactions in water microdroplets for the degradation of organic dyes. The efficiency of the microdroplet-based photoreactions was significantly improved with a degradation rate of 98.96% in microdroplets, while it was only 38.14% in the bulk solution. The enhanced degradation efficiency was due to the synergistic effect of the photocatalysis and photo-Fenton reactions in the microdroplets. First, the enrichment of both the dye (rhodamine B) and the catalyst (g-C3N4 nanosheets) at the aqueous interfaces enlarged the local surface concentration, playing a role in the reaction acceleration. Second, the spontaneously generated hydrogen peroxide (17.13 μM) at the aqueous interfaces triggered the photo-Fenton cycle and thus largely promoted the charge separation of g-C3N4 as well as the effective utilization of the photogenerated electrons and holes, leading to a significantly improved degradation efficiency of organic dyes. Further, we quantified the reaction kinetics of individual microdroplets in a real-time manner. The reaction constant in 10 μm microdroplets was 4.86 × 10-3 s-1, which was 22 times higher than that in the bulk phase (0.22 × 10-3 s-1). This study provided a better understanding of accelerated photoreactions at aqueous interfaces and a strategy for addressing the low efficiency of organic dye degradation.

Carbon Quantum Dots: Synthesis, Characteristics, and Quenching as Biocompatible Fluorescent Probes

Carbon quantum dots (CQDs), a new class of carbon-based nanomaterials, have emerged as nano-scaled probes with photoluminescence that have an eco-friendly and bio-compatible nature. Their cost-efficient synthesis and high photoluminescence quantum yields make them indispensable due to their application in opto-electronic devices, including biosensors, bioimaging, environmental monitoring, and light sources. This review provides intrinsic properties of CQDs such as their excitation-dependent emission, biocompatibility, and quenching properties. Diverse strategies for their easy synthesis are divided into bottom-up and top-down approaches and detailed herein. In particular, we highlight their luminescence properties, including quenching mechanisms that could even be utilized for the precise and rapid detection of biomolecules. We also discuss methodologies for the mitigation of fluorescence quenching, which is pivotal for the application of CQDs in biosensors and bioimaging.

Facile green treatment of mixed cellulose ester membranes by deep eutectic solvent to enhance dye removal and determination

Synthetic dye production and the consequent generation of dye-rich wastewater are major concerns of water quality in many countries. We developed a sustainable approach with deep eutectic solvent (DES) treatment to enhance the efficiency of mixed cellulose ester (MCE) membrane-based dye removal material. The DES composition and treatment conditions were optimized, and the treated membranes were comprehensively characterized. DES-treated membranes exhibited improved morphology, surface properties, and superior dye adsorption capabilities. Our study revealed that the adsorption process was chemically controlled and driven by electrostatic and hydrogen bond interactions. Thermodynamic analysis confirmed the endothermic and spontaneous nature of the adsorption process. Moreover, the treated membranes exhibited good separation performance for dye/salt mixtures. Additionally, we demonstrated selective adsorption of cationic dyes over anionic dyes using these treated membranes. This selectivity enabled the development of a membrane solid-phase extraction (MSPE) method for quantification of trace amount of dyes. Compared with other methods, DES-treated MCE membranes present a promising solution for efficient dye quantification and removal, offering a green and effective strategy to address water pollution stemming from synthetic dyes. Additionally, this study provides a novel strategy for green chemistry modification of cellulose-based materials.

Recent advances in modifications, biotechnology, and biomedical applications of chitosan-based materials: A review

Chitosan, a natural polysaccharide with recognized biocompatibility, non-toxicity, and cost-effectiveness, is primarily sourced from crustacean exoskeletons. Its inherent limitations such as poor water solubility, low thermal stability, and inadequate mechanical strength have hindered its widespread application. However, through modifications, chitosan can exhibit enhanced properties such as water solubility, antibacterial and antioxidant activities, adsorption capacity, and film-forming ability, opening up avenues for diverse applications. Despite these advancements, realizing the full potential of modified chitosan remains a challenge across various fields. The purpose of this review article is to conduct a comprehensive evaluation of the chemical modification techniques of chitosan and their applications in biotechnology and biomedical fields. It aims to overcome the inherent limitations of chitosan, such as low water solubility, poor thermal stability, and inadequate mechanical strength, thereby expanding its application potential across various domains. This review is structured into two main sections. The first part delves into the latest chemical modification techniques for chitosan derivatives, encompassing quaternization, Schiff base formation, acylation, carboxylation, and alkylation reactions. The second part provides an overview of the applications of chitosan and its derivatives in biotechnology and biomedicine, spanning areas such as wastewater treatment, the textile and food industries, agriculture, antibacterial and antiviral activities, drug delivery systems, wound dressings, dental materials, and tissue engineering. Additionally, the review discusses the challenges associated with these modifications and offers insights into potential future developments in chitosan-based materials. This review is anticipated to offer theoretical insights and practical guidance to scientists engaged in biotechnology and biomedical research.

Biofabrication of zinc oxide nanoparticles using Moringa oleifera, characterization and statistical optimization for their application in crystal violet adsorption

Crystal violet (Cry) is an essential textile dye belonging to the triphenylmethane group, that is widely used in the textile industry. It is also applied for paper printing and Gram staining. Previously, it was significant as a topical antiseptic due to its antibacterial, antifungal, and anthelmintic properties. Despite its various applications, crystal violet has been recognized as a biohazard dye due to its toxic and carcinogenic properties. It persists in the environment with long-lasting effects and has detrimental impacts. In this research, water extract from Moringa oleifera leaves is employed as environmentally friendly methods to synthesize zinc oxide nanoparticles (Mo/ZnO-NPs), and characterized by TEM, EDX, FT-IR, and Zeta potential. Mo/ZnO-NPs exhibit a Zeta potential of - 21.9 mV, and X-ray diffraction (XRD) analysis confirms their crystallographic structure. The size of the biogenic Mo/ZnO-NPs ranges from 5.52 to 41.59 nm. This study was designed to estimate and maximize the ability of Mo/ZnO-NPs to remove crystal violet using Central Composite Design (CCD), considering pH (ranging from 3 to 11), incubation time (ranging from 30 to 150), nanoparticles concentrations (ranging from 0.2 to 1.8 mg/mL), and crystal violet concentrations (ranging from 25 to 125 ppm). The maximum percentage value of removal of crystal violet by Mo/ZnO-NPs was 97.26 with optimal conditions of pH 9, incubation time 120 min, Mo/ZnO-NPs 1.4 mg/mL, and crystal violet concentration of 50 ppm. The best-predicted conditions that caused the highest removal of crystal violet (97.8%) were determined using the desirability function as pH 10, incubation time of 140 min, Mo/ZnO-NPs concentrations of 1.3 mg/mL, and a concentration of crystal violet of 80 ppm. Under these optimal conditions, the maximum experimental crystal violet removal% by Mo/ZnO-NPs was (98.7%) was verified. Mo/ZnO-NPs synthesized by Moringa oleifera can be a promising candidate for the adsorption of crystal violet.

Demonstration of adapted packed-bed bioreactor for accurate and rapid estimation of biochemical oxygen demand: insights into the influence of microbial community structure and functions

This study demonstrated a novel approach to accurately estimate 5-day biochemical oxygen demand (BOD5) in textile wastewater using a microbial consortium from food processing wastewater fixed on coconut fibers. Although glucose-glutamic acid (GGA) has been widely known as the most preferred substrates for microbial respiration, its calibration surprisingly resulted in an overestimation of BOD5 in textile wastewater due to its lower utilization rate compared to that of textile wastewater. After being adapted with a new nutrient environment composed of GGA and textile wastewater, the adapted packed-bed bioreactors (PBBRs) was capable of accurate estimation of BOD5 in textile wastewater using GGA standard solution. Metagenomic analysis revealed the dominance of the genera Enterobacter, Acinetobacter, Chryseobacterium, and Comamonas in the adapted microbial community, which are recognized for their significant potential in azo dye degradation. The imputed metagenome showed an enhanced showed an enhanced abundance of "Amino Acid Degradation" and "Carbohydrate Degradation" functions, confirming the improved ability of adapted community to utilization of GGA in the standard solution. These findings suggest that adaptation of exogenous microbial consortium to a nutrient environment composed of GGA and target wastewater may shift the community to that dominated by strains having both utilization ability of GGA and target compounds which, in turn, enhance the accuracy of the adapted PBBRs for estimation of BOD5 in target wastewater.

Green-synthesized silver nanoparticle-enhanced nanofiltration mixed matrix membranes for high-performance water purification

This study presents the fabrication and characterization of mixed matrix membranes (MMMs) incorporating green-synthesized silver nanoparticles (AgNPs) using Hibiscus Rosa sinensis extract within a polyethersulfone (PES) matrix for nanofiltration (NF) application. The membranes were evaluated for their pure water permeability, salt rejection, dye removal, and antifouling performance. Results showed that the membrane with 0.75 wt% AgNPs exhibited the highest pure water permeability of 36 L/m2 h-1 bar-1 attributed to increased porosity and enhanced hydrophilicity. Addition of 0.75wt% AgNPs resulted in significant improvements, with NaCl rejection increased from 32 to 57%, MgSO4 from 26 to 67%, and CaCl2 from 27 to 41%. Antifouling tests revealed that the 0.75 wt% AgNPs membrane had the lowest irreversible fouling and highest flux recovery due to the antimicrobial action and improved surface properties of AgNPs. Importantly, the performance of the fabricated membranes align with loose nanofiltation characteristcs, as evidence by high dye rejection rates coupled with moderate rejection of salts. This study highlights the potential of green-synthesized AgNPs as effective nanofillers for developing high-performance and environmentally sustainable membranes into wastewater treatment.

Photocatalytic Degradation of Dyes in Wastewater Using Solar Enhanced Nickel Oxide (NiO) Nanocatalysts Prepared by Chemical Methods

This study examined the surface morphology and photocatalytic activity of nickel oxide (NiO) nanoparticles prepared through a chemical method. The synthesized nanoparticle was characterized by using spectroscopic and microscopic techniques. Photocatalytic degradation of hazardous Eriochrome Black T (EBT) was carried out using the synthesized nanoparticle and the efficiency of the NiO used was determined. Highest degradation efficiency of 70% at 25 mg loading was observed at 40 min exposure time. The study concluded that the synthesized nanoparticles could be used in industrial wastewater treatment containing organic dyes.

Nanosilver-Biopolymer-Silica Composites: Preparation, and Structural and Adsorption Analysis with Evaluation of Antimicrobial Properties

In this article, we report on the research on the synthesis of composites based on a porous, highly ordered silica material modified by a metallic nanophase and chitosan biofilm. Due to the ordered pore system of the SBA-15 silica, this material proved to be a good carrier for both the biologically active nanophase (highly dispersed silver nanoparticles, AgNPs) and the adsorption active phase (chitosan). The antimicrobial susceptibility was determined against Gram-positive Staphylococcus aureus ATCC 25923, Gram-negative bacterial strains (Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, and Pseudomonas aeruginosa ATCC 27853), and yeast Candida albicans ATCC 90028. The zones of microbial growth inhibition correlated with the content of silver nanoparticles deposited in the composites and were the largest for C. albicans (14-21 mm) and S. aureus (12-17 mm). The suitability of the composites for the purification of water and wastewater from anionic pollutants was evaluated based on kinetic and equilibrium adsorption studies for the dye Acid Red 88. The composite with the highest amount of the chitosan component showed the greatest adsorption capacity (am) of 0.57 mmol/g and the most effective kinetics with a rate constant (log k) and half-time (t0.5) of -0.21 and 1.62 min, respectively. Due to their great practical importance, AgNP-chitosan-silica composites can aspire to be classified as functional materials combining the environmental problem with microbiological activity.

Treatment of Wastewater from Methylene Blue Dye and E. Coli Bacteria by High-Performance Fe3O4/rGO/TiO2 Nanocatalyst

Photocatalysis-based technology has insight into decreasing the disadvantages of traditional approaches and has been identified as an appropriate way to eliminate dyes and bacteria from wastewater. In this work, Fe3O4/rGO/TiO2 photocatalyst material was synthesized by a simple and fast hydrothermal method. The photocatalyst process results showed that Fe3O4/rGO/TiO2 nanocomposite degraded methylene blue dye completely in 4 min. Also, Fe3O4/rGO/TiO2 nanocomposite was very efficient (4.92 log reduction value) for E. Coli bacteria inactivation in 60 min photocatalyst process. The superparamagnetic behavior of Fe3O4/rGO/TiO2 nanocomposite was investigated by VSM analysis and magnetization saturation was obtained at about 38.46 emu/g which gives simple and fast separation from media to Fe3O4/rGO/TiO2 nanocatalyst. The structural and morphology properties of Fe3O4/rGO/TiO2 nanocomposite were studied by XRD, Raman, FT-IR, EDS, FESEM, and TEM analysis. The obtained results confirmed that Fe3O4/rGO/TiO2 nanocomposite is an efficient nanocatalyst for the treatment of MB dye and E. Coli. Bacteria from water, simultaneously.

Synthesis and characterization of nano iron oxide biochar composite for efficient removal of crystal violet from water

In the present study, Coconut Husk Biochar (CHB) was synthesize from widely available, locally sourced agro waste, coconut husk and characterized using different techniques like scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). CHB was tested for its ability to adsorb crystal violet (CV), a commonly used cationic dye, from water. It was capable of adsorbing more than 98 % of CV from water and follows Freundlich isotherm model with pseudo second order kinetics though the overall process was unfavourable. Moreover, separation of CHB from water after adsorption is a cumbersome process. Thus, unmodified CHB is not suitable for use as an adsorbent for CV. Magnetic nano iron oxide Biochar Composite (MBC) was synthesized by deposition of nano iron oxide (Fe3O4) onto its surface by co-precipitation method and characterized using SEM, XRD and FTIR. SEM analysis provided visual evidence of this deposition which was further confirmed by XRD and FTIR analysis. MBC was also effective in adsorbing more than 90 % of CV from aqueous solution though a decrease in adsorption capacity was observed. Adsorption data followed Langmuir isotherm model and pseudo second order kinetics. MBC is superparamagnetic and is strongly attracted to a small bar magnet, facilitating easy removal from water after CV adsorption.

A Facile Microwave-Promoted Formation of Highly Photoresponsive Au-Decorated TiO2 Nanorods for the Enhanced Photo-Degradation of Methylene Blue

The integration of noble metal nanoparticles (NPs) effectively modifies the electronic properties of semiconductor photocatalysts, leading to improved charge separation and enhanced photocatalytic performance. TiO2 nanorods decorated with Au NPs were successfully synthesized using a cost-effective, rapid microwave-assisted method in H2O2 and HF media for methylene blue (MB) degradation under visible light illumination. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 physisorption, and UV-vis spectroscopy were employed to characterize the structures, morphologies, compositions, and photoelectronic properties of the as-synthesized materials. The fusing of Au NPs effectively alters the electronic structure of TiO2, enhancing the charge separation efficiency and improved electrical conductivity. The HF treatment promotes the exposure of the highly reactive (001) and (101) crystalline facets. The improved photocatalytic activity of Au/TiO2, achieving 97% efficiency, is attributed to the surface plasmon resonance (SPR) effect of the Au NPs and the presence of oxygen vacancies. The photodegradation of MB using the TiO2/Au photocatalysts follows pseudo-first-order kinetics, highlighting the enhanced catalytic efficiency of the synthesized nanostructures. The exceptional properties of the binary Au/TiO2 photocatalysts, including the SPR effect, exposed crystallographic faces, and efficient charge carrier separation through a decrease in the recombination of electrons and holes, contribute to the photocatalytic degradation of MB.

Eco-friendly synthesis of CuO/Bi2O3 nanocomposite for efficient photocatalytic degradation of rhodamine B dye

Plant-mediated synthesized materials are receiving more attention than conventional ones due to their wide availability, ease of access, simple preparation methods, environmental benign, and possess superior physicochemical properties. In this work, plant extract-mediated CuO, Bi2O3, and CuO/Bi2O3 nanocomposite samples were successfully synthesized using bamboo leaves extract as a capping agent. These materials were utilized for the photodegradation of Rhodamine B (RhB) dye, which served as a model organic dye pollutant. The physicochemical characterization techniques such as XRD, SEM-EDS, FTIR, and DRS-UV-vis spectrophotometry provide insight into the crystal structure, morphology, surface functional groups, and optical properties. These analyses confirm the effective formation of CuO, Bi2O3, and CuO/Bi2O3 materials. Surprisingly, upon calcination at 450 °C for 4 h, the color of the nanocomposite changed from pale green to gray greenish, providing evidence for the formation of the CuO in CuO/Bi2O3 nanocomposite. The photocatalytic optimization parameters such as pH (4), catalyst load (35 mg), irradiation time (180 min) and concentration of RhB (10 mg L-1) dye were investigated. By coupling CuO with Bi2O3 nanoparticles resulted in an improved photocatalytic property for the degradation of RhB dye under optimal conditions. As a result, CuO/Bi2O3 nanocomposite exhibited a significantly boosted photocatalytic degradation efficiency (95.6%) compared to pure CuO (40.2%) and Bi2O3 (80.5%) photocatalysts, with good reusability. For comparison purpose, the photocatalytic degradation of RhB dye using selected photocatalyst was evaluated under dark and sunlight systems. This eco-friendly approach holds great potential for synthesis new nanocomposite with modified properties, thereby enabling the practical application of high-efficiency photocatalysts. The plausible mechanism of the electrons and holes transfer was proposed.

Amine-crosslinked lignin for water pollution attributable to organic dye remediation: Versatile adsorbent for selective dye removal and reusability

Lignin, an abundant natural resource, has not been effectively utilized. In this study, the functionality of lignin was enhanced through amination to produce amine-crosslinked lignin, and its adsorption behavior toward cationic and anionic dyes was investigated. Chemical structure analysis confirmed the successful introduction of amine groups, thereby improving the molecular weight and thermal stability of the optimized amine-crosslinked lignin. Additionally, the amine-crosslinked lignin exhibited a larger specific surface area than kraft lignin, as well as excellent adsorption capacity for both anionic and cationic dyes. Furthermore, it selectively adsorbed anionic and cationic dyes depending on pH conditions. The adsorption kinetics were described using a pseudo-second-order model, and the adsorption isotherms for congo red and methyl green were determined using the Langmuir and Freundlich equations, respectively. Additionally, the reusability and adsorption efficiency of the optimized amine-crosslinked lignin were evaluated, confirming its stable and repeatable adsorption efficiency for congo red and methyl green even after five repeated cycles. The assumed adsorption mechanism was attributed to electrostatic interactions. Therefore, the successful synthesis and excellent adsorption properties of amine-crosslinked lignin suggest its promising potential for environmentally friendly and efficient removal of both cationic and anionic dyes, thereby offering a sustainable solution for wastewater treatment and remediation.

Removal of Hazardous Organic Dyes from Liquid Wastes Using Advanced Nanomaterials

The presence of organic dyes in aqueous environments is extremely hazardous to life due to the toxicity of these compounds. Thus, its removal from these various aquatic media is of the utmost importance, and several technologies are constantly being tested to meet this goal. Among these technologies, various types of degradation and adsorption techniques are typically used, and of the various types of materials used within these technologies, nanomaterials are constantly being developed and investigated, likely due to the various properties that these nanomaterials have. This work reviewed recent developments (in 2023) about the use of these nanomaterials in the treatment of solutions contaminated with these toxic organic dyes.

Highly efficient adsorption of congo red and methyl orange dyes using mesoporous α-Mn2O3 nanoparticles synthesized with Pyracantha angustofolia fruit extract

Due to the many applications of manganese oxides in water treatment, this research aimed to synthesize α-Mn2O3 nanoparticles through a green method and investigate the dye adsorption capacity of them. The α-Mn2O3 nanoparticles were successfully synthesized using KMnO4 and aqueous extract of Pyracantha angustofolia fruits under hydrothermal conditions and calcination. The products were identified using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and scanning electron microscopy (SEM) analyses. The adsorption capacity of methyl orange (MO) and Congo red (CR) dyes were evaluated at different concentrations (25, 50, and 75 ppm) using α-Mn2O3 nanoparticles. Results revealed the spherical and porous structure of α-Mn2O3 nanoparticles with a specific surface area of 21.7 m2.g-1. Dye removal significantly increased with pH decrement. The adsorption capacity for MO and CR was 73.07 and 70.70 mg.g-1, respectively. The adsorption data of both dyes followed a pseudo-second-order kinetic model. The best fitted models for MO and CR adsorption were the Langmuir isotherm and the Dubinin-Radushkevich, respectively. In addition, a possible adsorption mechanism was proposed for both dyes. The findings showed that α-Mn2O3 nanoparticles are very efficient adsorbents for removing anionic dyes.

Peroxydisulfate-based Non-radical Oxidation of Rhodamine B by Fe-Mn Doped Granular Activated Carbon: Kinetics and Mechanism Study

While numerous persulfate-based advanced oxidation processes (AOPs) have been studied based on fancy catalysts, the practical combination of Fe or Mn modified granular activated carbon (GAC) has seldom been investigated. The present study focused on a green and readily synthesized Fe-Mn bimetallic oxide doped GAC (Fe-Mn@GAC), to uncover its catalytic kinetics and mechanism when used in the peroxydisulfate (PDS)-based oxidation process for degrading Rhodamine B (RhB), a representative xenobiotic dye. The synthesized Fe-Mn@GAC was characterized by SEM-EDS, XRD, ICP-OES and XPS analyses to confirm its physicochemical properties. The catalytic kinetics of Fe-Mn@GAC+PDS system were evaluated under varying conditions, including PDS and catalyst dosages, solution pH, and the presence of anions. It was found Fe-Mn@GAC exhibited robust catalytic performance, being insensitive to a wide pH range from 3 to 11, and the presence of anions such as Cl-, SO4 2-, NO3 - and CO3 2-. The catalytic mechanism was investigated by EPR and quenching experiments. The results indicated the catalytic system processed a non-radical oxidation pathway, dominated by direct electron transfer between RhB and Fe-Mn@GAC, with singlet oxygen (1O2) playing a secondary role. The catalytic system also managed to maintain a RhB removal above 81 % in successive 10 cycles, and recover to 89.5 % after simple DI water rinse, showing great reusability. The catalytic system was further challenged by real dye-containing wastewater, achieving a decolorization rate of 84.5 %. This work not only provides fresh insight into the kinetics and mechanism of the Fe-Mn@GAC+PDS catalytic system, but also demonstrates its potential in the practical application in real dye-containing wastewater treatment.

Catalytic reduction of nitroarenes by palladium nanoparticles decorated silica@poly(chitosan-N-isopropylacrylamide-methacrylic acid) hybrid microgels

Conversion of toxic nitroarenes into less toxic aryl amines, which are the most suitable precursors for different types of compounds, is done with various materials which are costly or take more time for this conversion. In this regards, a silica@poly(chitosan-N-isopropylacrylamide-methacrylic acid) Si@P(CS-NIPAM-MAA) Si@P(CNM) core-shell microgel system was synthesized through free radical precipitation polymerization (FRPP) and then fabricated with palladium nanoparticles (Pd NPs) by in situ-reduction method to form Si@Pd-P(CNM) and characterized with XRD, TEM, FTIR, SEM, and EDX. The catalytic efficiency of Si@Pd-P(CNM) hybrid microgels was studied for reduction of 4-nitroaniline (4NiA) under diverse conditions. Different nitroarenes were successfully transformed into their corresponding aryl amines with high yields using the Si@Pd-P(CNM) system as catalyst and NaBH4 as reductant. The Si@Pd-P(CNM) catalyst exhibited remarkable catalytic efficiency and recyclability as well as maintaining its catalytic effectiveness over multiple cycles.

N-doped lignin-based activated carbon aerogel derived from bamboo black pulp liquor for efficient removal of malachite green in wastewater

In this study, a lignin-based aerogel (LA) was prepared through acid precipitation of BPBL, followed by sol-gel method and freeze-drying. Additionally, a one-step activation-carbonization method was used to acquire nitrogen-doped lignin-based activated carbon aerogel (NLACA). The adsorption and catalytic degradation performance for malachite green (MG) were examined. The specific surface area of NLACA after N-doping was 2644.5 m2/g. The adsorption capacity for MG was increased to 3433 mg/g with the presence of nitrogenous functional groups on surface of NLACA compared without N-doping. Meanwhile, non-radical singlet oxygen is the primary active substance and degradation efficiency arrives at 91.8% after the catalytic degradation within 20 min and it has good stability and reuse. Three possible degradation pathways during degradation were analyzed by LC-MS technique. The adsorption isotherm and kinetic data demonstrated conformity with both the Langmuir model and the pseudo-second-order kinetic model. The primary mechanisms of the adsorption for MG dyes on NLACA include hydrogen bonding, π-π interactions, attraction of electrostatic and pore filling. Hence, NLACA derived from BPBL acts as a cost-effective and high-performance adsorbent and catalyst for removal of MG in dye wastewater. This concept introduces an innovative approach of "treatment of waste with waste" for developing a low-consumption, high-efficiency dye wastewater treatment and provides significant reference to treatment dye wastewater.

Removal of organic contamination from wastewater using granular activated carbon modified-Polyethylene glycol: Characterization, kinetics and isotherm study

To effectively remove Diazinon (DZ), Amoxicillin (AMX), and Crystal Violet (CV) from aquatic environments, a novel granular activated carbon (GAC) modified with Polyethylene glycol 600 (PEG) was created and manufactured. The chemical properties were investigated using a variety of characteristic analyses, including FT-IR, XRD, FESEM, and N2 adsorption/desorption. The effectiveness of GAC-PEG's adsorption for the removal of DZ, AMX, and CV was assessed under a variety of conditions, including a pH of 4-9 for the solution, 0.003-0.05 g doses of adsorbent, 50-400 ppm starting concentration, and a reaction time of 5-25 min. For DZ, AMX, and CV adsorption, the maximum adsorption capacity (Qmax) was 1163.933, 1163.100, and 1150.300 mg g-1, respectively. The Langmuir isotherm described all of the data from these adsorption experiments, and the pseudo-second-order well explains all-adsorption kinetics. Most contacts between molecules, electrostatic interactions, π-π interactions, hydrogen bonding, and entrapment in the modified CAG network were used to carry out the DZ, AMX, and CV adsorption on the GAC-PEG. The retrievability of the prepared adsorbent was successfully investigated in studies up to two cycles without loss of adsorption efficiency, and it was shown that it can be efficiently separated.

In-Brain Multiphoton Imaging of Vaterite Cargoes Loaded with Carbon Dots

Biocompatible fluorescent agents are key contributors to the theranostic paradigm by enabling real-time in vivo imaging. This study explores the optical properties of phenylenediamine carbon dots (CDs) and demonstrates their potential for fluorescence imaging in cells and brain blood vessels. The nonlinear absorption cross-section of the CDs was measured and achieved values near 50 Goeppert-Mayer (GM) units with efficient excitation in the 775-895 nm spectral range. Mesoporous vaterite nanoparticles were loaded with CDs to examine the possibility of a biocompatible imaging platform. Efficient one- and two-photon imaging of the CD-vaterite composites uptaken by diverse cells was demonstrated. For an in vivo scenario, CD-vaterite composites were injected into the bloodstream of a mouse, and their flow was monitored within the blood vessels of the brain through a cranial window. These results show the potential of the platform for high-brightness biocompatible imaging with the potential for both sensing and simultaneous drug delivery.

Formulation of silver phosphate/graphene/silica nanocomposite for enhancing the photocatalytic degradation of trypan blue dye in aqueous solution

Photocatalytic degradation of several harmful organic compounds has been presented as a potential approach to detoxify water in recent decades. Trypan Blue (TB) is an acidic azo dye used to distinguish live cells from dead ones and it's classified as a carcinogenic dye. In this study, silver phosphate (Ag3PO4) nanoparticles and novel Ag3PO4/graphene/SiO2 nanocomposite have been successfully prepared via simple precipitation method. Afterward, their physical properties, chemical composition, and morphology have been characterized using SEM, EDS, TEM, SAED, BET, XRD, FTIR and UV-VIS spectroscopy. The specific surface area of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite were reported to be 1.53 and 84.97 m2/g, respectively. The band gap energy of Ag3PO4 and Ag3PO4/G/SiO2 nanocomposite was measured to be 2.4 and 2.307 eV, respectively. Photocatalytic degradation of Trypan blue (TB) was studied at different parameters such as pH, catalyst dosage, initial concentration, and contact time. The results showed that, at initial dye concentration of 20 ppm, pH = 2, and using 0.03 g of Ag3PO4/G/SiO2 as a photocatalyst, the degradation percent of TB dye in the aqueous solution was 98.7% within 10 min of light exposure. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the photocatalytic degradation kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order kinetic model. Finally, the possible photocatalytic performance mechanism of Ag3PO4/G/SiO2 was proposed.

A mechanochemically synthesized Schiff-base engineered 2D mixed-linker MOF for CO2 capture and cationic dye removal

Developing synthetic strategies for smart materials for the adsorption and separation of toxic chemicals is of great importance. Metal-organic frameworks (MOFs) have been proven to be outstanding adsorbent materials that possess excellent pollutant removal performances in wastewater treatment, including dye recycling. In this work, a neutral Cd(II) based 2D framework with a dual ligand strategy involving -OH functionalized 5-hydroxyisophthalic acid (5-OH-H2IPA) and the amide decorated Schiff base ligand (E)-N'-(pyridin-4-ylmethylene)isonicotinohydrazide (L) has been synthesized by different synthetic routes and characterized by various analytical methods. Thus, crystals of {[Cd(5-OH-IPA)(L)]·CH3OH}n synthesized via diffusion (ADES-7D) and the phase pure bulk product synthesized by conventional reflux (ADES-7C) and the mechanochemical grinding method (ADES-7M) have been established using PXRD data of the respective product showing identical simulated SXRD data to those of ADES-7D. The mechanochemically synthesized ADES-7M possesses a better surface area and CO2 adsorption capability compared to ADES-7C, which is also supported by electron microscopy and particle size measurements. Furthermore, ADES-7 can be used as an efficient adsorbent material for the reversible, selective adsorption (42-99%) and separation of the cationic dyes malachite green (MG), methyl violet (MV), methylene blue (MB), and rhodamine B (RhB) from the mixture of cationic/anionic dyes (methyl orange (MO) and bromocresol green (BCG)) in the aqueous phase. Specifically, ADES-7M possesses better dye capture capability compared to ADES-7C, even in the case of the bigger dye RhB with adsorption differences of 2.38 to 1.01 mg g-1, respectively. The dye adsorption kinetics follows pseudo-second-order kinetics, and the dye adsorption isotherm fits well with the Langmuir/Freundlich adsorption isotherm models. The probable mechanism of adsorption involving the supramolecular interaction between the host MOF and the guest dye has also been proposed.

The efficiency of Raphia hookeri adsorbent in indigo carmine dye removal: Economy depth via chemometrics

The remediation of dye pollutants remains a concern in contemporary water management practices. Hence, the need for efficient and cost-effective techniques for dye removal from wastewater. In this study, the epicarp of Raphia hookeri fruits was treated with orthophosphoric acid for enhanced porosity and efficiency in the uptake of Indigo carmine dye (ICD). Treated Raphia hookeri fruit waste (RHPW) presented morphologically distributed pores as well as high porosity with Branneur-Emmet-Teller (BET) surface area of 945.43 m2/g. RHPW displayed functional groups suitable for adsorption. The maximum ICD uptake was observed at pH 5 while the maximum uptake (qmax) was 20.41 mg/g in the concentration range of 2-10 mg/L. Freundlich isotherm and Pseudo-second order kinetics well-described equilibrium and kinetics data respectively. This indicated a multilayered adsorption. The Dubinin-Radushkecich model energy value was 40.82 kJ/mol, indicating chemical adsorption. The ridge regression, the Lasso and the Elastic net statistical models were used to establish a positive relationship between the various adsorption operational parameters studied. Lasso provided the best result based on the estimated mean squared error. The RHPW-ICD adsorption system was more favorable at room temperature, as the removal efficiency decreased with temperature rise. The findings established Raphia hookeri fruit epicarp as an economical and sustainable precursor for the preparation of potent adsorbent for Indigo carmine dye removal. This can find possible application in wastewater treatment.

Cellulose-based materials in environmental protection: A scientometric and visual analysis review

As sustainable materials, cellulose-based materials have attracted significant attention in the field of environmental protection, resulting in the publication of numerous academic papers. However, there is a scarcity of literature that involving scientometric analysis within this specific domain. This review aims to address this gap and highlight recent research in this field by utilizing scientometric analysis and a historical review. As a result, 21 highly cited articles and 10 mostly productive journals were selected out. The scientometric analysis reveals that recent studies were objectively clustered into five interconnected main themes: extraction of cellulose from raw materials and its degradation, adsorption of pollutants using cellulose-based materials, cellulose-acetate-based membrane materials, nanocellulose-based materials, and other cellulose-based materials such as carboxymethyl cellulose and bacterial cellulose for environmental protection. Analyzing the distribution of author keywords and thoroughly examining relevant literature, the research focuses within these five themes were summarized. In the future, the development of eco-friendly and cost-effective methods for extracting and preparing cellulose and its derivatives, particularly nanocellulose-based materials, remains an enduring pursuit. Additionally, machine learning techniques holds promise for the advancement and application of cellulose-based materials. Furthermore, there is potential to expand the research and application scope of cellulose-based materials for environmental protection.

Highly efficient piezocatalytic composite with chitosan biopolymeric membranes and bismuth ferrite nanoparticles for dye decomposition and pathogenic S. aureus bacteria killing

Untreated wastewater harbors dangerous pathogens, chemicals, and pollutants, posing grave public health threats. Nowadays, there is a rising demand for eco-friendly technologies for wastewater treatment. Recently, piezoelectric materials-based wastewater treatment technology has captured considerable interest among researchers because of its noninvasiveness and rapidity. Herein, a highly efficient piezoelectric composite material is designed with chitosan-incorporated bismuth ferrite (BFO) nanocrystals, to decompose pollutants and ablate bacteria in wastewater. On one hand, piezoelectric BFO has shown exclusive piezo-coefficient for ultrasound-mediated reactive oxygen species (ROS) production. On the other hand, chitosan depicts its biocompatible nature, which not only promotes cellular adhesion but also significantly elevates the ROS production capabilities of BFO under ultrasound. The synergistic effect of these two piezoelectric units in one composite entity shows an improved ROS production, eradicating ∼87.8% of Rhodamine B within 80 min under soft ultrasound treatment (rate constant, k ≈ 0.02866 min-1). After performing the scavenger experiment, it has been found that hydroxyl radicals are the dominating factor in this case. Further, the reusability of the composite piezocatalyst is confirmed through multiple cycles (five times) of the same experiment. The high polarizability of the composite material facilitates the generation of piezoelectric power through finger tapping (∼12.05 V), producing substantial instantaneous piezo-voltage. Moreover, the sample exhibits remarkable antibacterial activity, with nearly 99% bacterial eradication within 30 min. This indicates a significant advancement in utilizing biopolymeric composites incorporated with BFO for fabricating versatile devices with multidimensional applications.

Toxicity of individual and mixture of organic compounds to P. Phosphoreum and S. Capricornutum using interpretable simple structural parameters

Human and environmental ecosystem beings are exposed to multicomponent compound mixtures but the toxicity nature of compound mixtures is not alike to the individual chemicals. This work introduces four models for the prediction of the negative logarithm of median effective concentration (pEC50) of individual chemicals to marine bacteria Photobacterium Phosphoreum (P. Phosphoreum) and algal test species Selenastrum Capricornutum (S. Capricornutum) as well as their mixtures to P. Phosphoreum, and S. Capricornutum. These models provide the simplest approaches for the forecast of pEC50 of some classes of organic compounds from their interpretable structural parameters. Due to the lack of adequate toxicity data for chemical mixtures, the largest available experimental data of individual chemicals (55 data) and their mixtures (99 data) are used to derive the new correlations. The models of individual chemicals are based on two simple structural parameters but chemical mixture models require further interaction terms. The new model's results are compared with the outputs of the best accessible quantitative structure-activity relationships (QSARs) models. Various statistical parameters are done on the new and comparative complex QSAR models, which confirm the higher reliability and simplicity of the new correlations.

Open-Nanogap-Induced Strong Electromagnetic Enhancement in Au/AgAu Monolayer as a Stable and Uniform SERS Substrate for Ultrasensitive Detection

Nanogap-based plasmonic metal nanocrystals have been applied in surface-enhanced Raman scattering detection, while the closed and insufficient electromagnetic fields as well as the nonreproducible Raman signal of the substrate greatly restrict the actual application. Herein, a highly uniform Au/AgAu monolayer with abundant nanogaps and huge electromagnetic enhancement is prepared, which shows ultrasensitive and reproducible SERS detection. Au/AgAu with an inner nanogap is first prepared based on Au nanotriangles, and the nanogap is opened from the three tips via a subsequent etching process. The open-gap Au/AgAu displays much higher SERS efficiency than Au and Au/AgAu with an inner nanogap on detecting crystal violet due to the open-gap induced electromagnetic enhancement and improved molecular absorption. Furthermore, the open-gap Au/AgAu monolayer is prepared via interfacial self-assembly, which shows further improved SERS due to the dense and strong hotspots in the nanocavities induced by the electromagnetic coupling between adjacent open gaps. The monolayer possesses excellent signal stability, uniformity, and reproducibility. The analytic enhancement factor and relative standard deviation reach to 2.12 × 108 and 4.65% on detecting crystal violet, respectively. Moreover, the monolayer achieves efficient detection of thiram in apple juice, biphenyl-4-thiol, 4-mercaptobenzoic, melamine, and a mixed solution of four different molecules, showing great promise in practical detection.

Removal of Anionic Methyl Orange Dye from Water by Poly[2-methyl-1H-indole] Derivatives: Investigation of Kinetics and Isotherms of Adsorption

The adsorption properties toward methyl orange (MO) were evaluated for poly[2-methyl-1H-indole] and its derivatives. The influence of pH, ionic strength of solution, composition, and amount of sorbent on the adsorption of MO dye was investigated; the kinetics of dye adsorption was studied. The adsorption isotherms were analyzed using different models of sorption equilibrium. The presence of chemical interaction between polyindoles and dye was proved by IR and UV spectroscopy methods. The sorption of MO with polymers is realized mainly due to the formation of electrostatic interactions between the sulfogroup of the dye and the imino group of the sorbent. Microphotographs demonstrate the change in the morphology of polyindoles after adsorption, which further confirms the structural changes in the polymers. It was found that the main factors affecting the sorption capacity of the studied materials are the position and nature of substituents in the polymers and the sorption conditions. For example, polyindoles containing a methoxy group in their structure (o-OMePIn and m-OMePIn) have the best sorption activity. These polymers are effective in adsorbing dyes, which means that they can be used in wastewater treatment.

Enhanced Adsorption of Methyl Orange from Aqueous Phase Using Chitosan-Palmer Amaranth Biochar Composite Microspheres

To develop valuable applications for the invasive weed Palmer amaranth, we utilized it as a novel biochar source and explored its potential for methyl orange adsorption through the synthesis of chitosan-encapsulated Palmer amaranth biochar composite microspheres. Firstly, the prepared microspheres were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy and were demonstrated to have a surface area of 19.6 m2/g, a total pore volume of 0.0664 cm3/g and an average pore diameter of 10.6 nm. Then, the influences of pH, dosage and salt type and concentration on the adsorption efficiency were systematically investigated alongside the adsorption kinetics, isotherms, and thermodynamics. The results reveal that the highest adsorption capacity of methyl orange was obtained at pH 4.0. The adsorption process was well fitted by a pseudo-second-order kinetic model and the Langmuir isotherm model, and was spontaneous and endothermic. Through the Langmuir model, the maximal adsorption capacities of methyl orange were calculated as 495.0, 537.1 and 554.3 mg/g at 25.0, 35.0 and 45.0 °C, respectively. Subsequently, the adsorption mechanisms were elucidated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy investigations. It is indicated that electrostatic interactions, hydrogen bonding, π-π interactions and hydrophobic interactions between methyl orange and the composite microspheres were pivotal for the adsorption process. Finally, the regeneration studies demonstrated that after five adsorption-desorption cycles, the microspheres still maintained 93.6% of their initial adsorption capacity for methyl orange. This work not only presents a promising method for mitigating methyl orange pollution but also offers a sustainable approach to managing Palmer amaranth invasion.

Peroxymonosulfate enhanced photocatalytic degradation of organic dye by metal-free TpTt-COF under visible light irradiation

Recently, the activation of persulfate (PDS) by non-metallic photocatalysts under visible light has attracted significant interest in applications in environmental remediation. This study presents a pioneering investigation into the combined application of the TpTt-COF and PMS for visible light degradation of organic dyes. Synthesized orange TpTt-COF monomers exhibit exceptional crystallinity, a 2D structure, and notable stability in harsh conditions. The broad visible light absorption around a wavelength of 708 nm. The TpTt-COF emerges as a promising candidate for photocatalytic dye degradation. The study addresses high charge recombination in the TpTt-COF, highlighting the crucial role of its electron donor and acceptor for the PMS activation. Comparative analyses against traditional photocatalytic materials, such as the metal-free carbon-based material g-C3N4 and transition metal-containing TiO2, demonstrate TpTt-COF's superior performance, generating diverse free radicals. In simulated experiments, the TpTt-COF's degradation rate surpasses PMS-combined g-C3N4 by 13.9 times. and 1.6 times higher than the TpTt-COF alone. Remarkably, the TpTt-COF maintains high activity under harsh environments. Investigations into the degradation mechanism and the TpTt-COF's reusability reveal its efficiency and stability. Under visible light, TpTt-COF facilitates efficient electron-hole separation. Combining the TpTt-COF with PMS produces various radicals, ensuring effective separation and a synergistic effect. Radical quenching experiments confirm the pivotal role of O2-· radicals, while ·OH and SO4-· radicals intensify the degradation. After five cycles, TpTt-COF maintains an impressive 83.2% degradation efficiency. This study introduces an efficient photocatalytic system mediated by PMS and valuable insights into governing mechanisms for organic pollutant degradation in water environments.

Effect of Shape and Size on Synthesized Triple (Co/Ni/Zn)-Doped α-Fe2O3 Nanoparticles on their Photocatalytic and Scavenging Properties

Co/Ni/Zn triple doped [Formula: see text]-Fe2O3 nanoparticles (NPs) have been synthesized via polyvinylpyrrolidone (PVP)/Azadirachta indica (A. Indica) leaf extract coating. XRD, UV–Vis, SEM, TEM, EDS, Raman spectroscopy, FTIR, VSM were used to characterize the synthesized NPs. XRD pattern revealed that the crystallite size of NPs ranges from 14[Formula: see text]nm to 21[Formula: see text]nm. Spherical NPs were found by SEM/TEM examination ranging from 16[Formula: see text]nm to 26[Formula: see text]nm of doped [Formula: see text]-Fe2O3 NPs. Analysis of the magnetic properties of [Formula: see text]-Fe2O3 NPs revealed antiferromagnetic characteristics, convergence between magnetization curves (MS), and switching field distribution dM/dh below an irreversible temperature of [Formula: see text][Formula: see text]K. Produced catalyst was used for the degradation of anionic azo dye Malachite green (MG) and Rhodamine blue (RhB) dyes under the influence of UV radiation. RhB and MG were reduced as a result of the doped [Formula: see text]-Fe2O3 catalyzing the conversion of dissolved O2 to hydroxyl radicals (OH) when exposed to visible light. This shows that the main active radical specifically engaged in the photo-catalytic breakdown of dyes is OH. The most effective photo-catalyst was determined by investigating the proposed doped [Formula: see text]-Fe2O3 NPs reusability over three cycles. The catalyst was retrieved and utilized three times after the reaction without suffering a substantial loss of catalytic activity. The plant-mediated [Formula: see text]-Fe2O3 NPs have significant antioxidant activity due to their higher phenolic content. These have a promising future with potential applications in health, aging, food preservation, cosmetics, agriculture and environmental protection.

Applications of hollow nanostructures in water treatment considering organic, inorganic, and bacterial pollutants

One of the major issues of modern society is water contamination with different organic, inorganic, and contaminants bacteria. Finding cost-effective and efficient materials and methods for water treatment and environment remediation is among the scientists' most important considerations. Hollow-structured nanomaterials, including hollow fiber membranes, hollow spheres, hollow nanoboxes, etc., have shown an exciting capability for wastewater refinement approaches, including membrane technology, adsorption, and photocatalytic procedure due to their extremely high specific surface area, high porosity, unique morphology, and low density. Diverse hollow nanostructures could potentially eliminate organic contaminants, including dyes, antibiotics, oil/water emulsions, pesticides, and other phenolic compounds, inorganic pollutants, such as heavy metal ions, salts, phosphate, bromate, and other ions, and bacteria contaminations. Here, a comprehensive overview of hollow nanostructures' fabrication and modification, water contaminant classification, and recent studies in the water treatment field using hollow-structured nanomaterials with a comparative attitude have been provided, indicating the privilege abd detriments of this class of nanomaterials. Eventually, the future outlook of employing hollow nanomaterials in water refinery systems and the upcoming challenges arising in scaling up are also propounded.

Exploring microgel adsorption: synthesis, classification, and pollutant removal dynamics

Microgels have gained significant importance for the removal of pollutants owing to their stimulus-responsive behavior, high stability, and reusable capacity. However, despite these advantages, several hurdles need to be overcome to fully maximize their potential as effective adsorbents for eradicating various contaminants from the environment, such as metallic cations, organic compounds, anions, harmful gases, and dyes. Therefore, a critical review on the adsorption of pollutants by microgels is needed. In this regard, this review presents the latest developments in the adsorptive properties of microgels. The synthetic methods, architectural structures, and stimulus-responsive behavior of microgels are explained in detail. In addition, this review explores various factors that directly influence the adsorption of pollutants by microgels, such as pH, feed composition, content of pollutants, content of comonomers, agitation time, temperature, microgel dose, nature of both adsorbates (pollutants) and adsorbents (microgels), nature of the medium, and ionic strength. Various adsorption isotherms are also explored together with the kinetic aspects of the adsorption process to provide a comprehensive understanding.

Endophytic Aspergillus hiratsukae mediated biosynthesis of silver nanoparticles and their antimicrobial and photocatalytic activities

In the current study, endophytic Aspergillus hiratsukae was used for the biosynthesis of silver nanoparticles (Ag-NPs) for the first time. The characterizations were performed using X ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. The obtained results demonstrated the successful formation of crystalline, spherical Ag-NPs with particle diameters ranging from 16 to 31 nm. The FT-IR studied and displayed the various functional groups involved, which played a role in capping and reducing agents for Ag-NPs production. The SEM-EDX revealed that the main constituent of the AS-formed sample was primarily Ag, with a weight percentage of 64.2%. The mycosynthesized Ag-NPs were assessed for antimicrobial as well as photocatalytic activities. The antimicrobial results indicated that the synthesized Ag-NPs possess notable antibacterial efficacy against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli, with minimum inhibitory concentrations (MICs) of Ag-NPs ranging from 62.5 to 250 μg/mL. Moreover, the biosynthesized Ag-NPs demonstrated weak antifungal activity against Aspergillus brasiliensis and Candida albicans, with MICs of 500 and 1,000 μg/mL, respectively. In addition, the mycosynthesized Ag-NPs exhibited photocatalytic activity toward acid black 2 (nigrosine) dye under both light and dark stimulation. Notably, After 300 min exposure to light, the nigrosine dye was degraded by 93%. In contrast, 51% degradation was observed after 300 min in darkness. In conclusion, Ag-NPs were successfully biosynthesized using endophytic A. hiratsukae and also exhibited antimicrobial and photocatalytic activities that can be used in environmental applications.

Highly flexible copper tape decorated with Ag nanoarrays as ultrasensitive SERS platforms for multi-hazardous pollutant sensing

A highly flexible and cost-effective copper tape decorated with silver nanoparticles (Cu-TAg) has been developed for surface-enhanced Raman spectroscopy (SERS) sensing of multi-hazardous environmental pollutants. Highly ordered and spherical-shaped silver nanoarrays have been fabricated using a low-cost thermal evaporation method. The structural, morphological, and optical properties of Cu-TAg sensors have been studied and correlated to the corresponding SERS performances. The size of nanoparticles has been successively tuned by varying the deposition time from 5 to 25 s. The nanoparticle sizes were enhanced with an increase in the evaporation time. SERS investigations have revealed that the sensing potential is subsequently improved with an increase in deposition time up to 10 s and then deteriorates with further increase in Ag deposition. The highest SERS activity was acquired for an optimum size of ~ 37 nm; further simulation studies confirmed this observation. Moreover, Cu-TAg sensors exhibited high sensitivity, reproducibility, and recycling characteristics to be used as excellent chemo-sensors. The lower detection limit estimation revealed that it can sense even in the pico-molar range for sensing of rhodamine 6G and methylene blue. The estimated enhancement factor of the sensor is found to be 9.4 × 107. Molecular-specific sensing of a wide range of pollutants such as rhodamine 6G, alizarin red, methylene blue, butylated hydroxy anisole, and penicillin-streptomycin is demonstrated with high efficiencies for micromolar spiked samples. Copper tape functionalized with Ag arrays thus demonstrated to be a promising candidate for low-cost and reusable chemo-sensors for environmental remediation applications.

Fabrication of carbon-based materials derived from a cobalt-based organic framework for enhancing photocatalytic degradation of dyes

The pyrolysis of metal-organic frameworks (MOFs) has emerged as a promising route to synthesize carbon/metal oxide-based materials with diverse phase compositions, morphologies, sizes and surface areas. In this paper, 1,3,5-benzoic acid (BTC) and 2,4,6-tri(4-pyridinyl)-1-pyridine (TPP) were used as ligands to prepare a novel cobalt-based MOF (Co-MOF) which was used as a precursor to obtain five carbon-based materials at different temperatures (Co-C200/400/600/800/1000). Furthermore, five dyes were used as degradation targets to investigate the photocatalytic degradation performance of the title materials under UV light irradiation. Co-C1000 exhibited the best photocatalytic degradation performance for methyl orange (MO), and the degradation rate could reach 99.21%. The enhanced photocatalytic activity was attributed to narrower band-gaps and a synergistic effect originating from the well-aligned straddling band structures between Co/CoO/Co3O4 and C, also resulting in a faster interfacial charge transfer during the photocatalytic reaction. This study will aid in the development of photocatalysts generated from carbon-based materials via the pyrolysis transformation of MOFs, therefore greatly enhancing the photocatalytic performance.

Highly Efficient Biosorption of Cationic Dyes via Biopolymeric Adsorbent-Material-Based Pectin Extract Polysaccharide and Carrageenan Grafted to Cellulosic Nonwoven Textile

Water scarcity and contamination have emerged as critical global challenges, requiring the development of effective and sustainable solutions for the treatment of contaminated water. Recently, functionalized polymer biomaterials have garnered significant interest because of their potential for a wide range of water treatment applications. Accordingly, this paper highlights the design of a new adsorbent material based on a cellulosic nonwoven textile grafted with two extracted biopolymers. The layer-by-layer grafting technique was used for the polyelectrolyte multi-layer (PEM) biosorbent production. Firstly, we extracted a Suaeda fruticosa polysaccharide (SFP) and confirmed its pectin-like polysaccharide structure via SEC, NMR spectroscopy, and chemical composition analyses. Afterward, the grafting was designed via an alternating multi-deposition of layers of SFP polymer and carrageenan crosslinked with 1,2,3,4-butanetetracarboxylic acid (BTCA). FT-IR and SEM were used to characterize the chemical and morphological characteristics of the designed material. Chemical grafting via polyesterification reactions of the PEM biosorbent was confirmed through FT-IR analysis. SEM revealed the total filling of material microspaces with layers of grafted biopolymers and a rougher surface morphology. The assessment of the swelling behavior revealed a significant increase in the hydrophilicity of the produced adsorbent system, a required property for efficient sorption potential. The evaluation of the adsorption capabilities using the methylene blue (MB) as cationic dye was conducted in various experimental settings, changing factors such as the pH, time, temperature, and initial concentration of dye. For the untreated and grafted materials, the greatest adsorbed amounts of MB were 130.6 mg/g and 802.6 mg/g, respectively (pH = 4, T = 22 C, duration = 120 min, and dye concentration = 600 mg/L). The high adsorption performance, compared to other reported materials, was due to the presence of a large number of hydroxyl, sulfonate, and carboxylic functional groups in the biosorbent polymeric system. The adsorption process fitted well with the pseudo-first-order kinetic model and Langmuir/Temkin adsorption isotherms. This newly developed multi-layered biosorbent shows promise as an excellent adsorption resultant and cheap-cost/easy preparation alternative for treating industrial wastewater.

A Sustainable and Regenerative Process for the Treatment of Textile Effluents Using Nonphotocatalytic Water Splitting by Nanoporous Oxygen-Deficient Ferrite

Water is crucial for life. Being the world's third-largest industry, the textile industry pollutes 93 billion cubic meters of water each year. Only 28% of textile wastewater is treated by lower- to middle-income countries due to the costly treatment methods. The present work demonstrates the utilization of surface oxygen defects and nanopores in Mg0.8Li0.2Fe2O4 (Li-MgF) to treat textile effluents by a highly economical, scalable, and eco-friendly process. Nanoporous, oxygen-deficient Li-MgF splits water by a nonphotocatalytic process at room temperature to produce green electricity as hydroelectric cell. The adsorbent Li-MgF can be easily regenerated by heat treatment. A 70-90% reduction in the UV absorption intensity of adsorbent-treated textile effluents was observed by UV-visible spectroscopy. The oxygen defects on Li-MgF surface and nanopores were confirmed by X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller (BET) measurements, respectively. To analyze the adsorption mechanism, three known organic water-soluble dyes, brilliant green, crystal violet, and congo red, were treated with nanoporous Li-MgF. The dye decolorization efficiency of Li-MgF was recorded to be 99.84, 99.27, and 99.31% at 250 μM concentrations of brilliant green, congo red, and crystal violet, respectively. The results of Fourier transform infrared (FTIR) spectroscopy confirmed the presence of dyes on the material surface attached through hydroxyl groups generated by water splitting on the surface of the material. Total organic carbon analysis confirmed the removal of organic carbon from the dye solutions by 82.8, 77.0, and 46.5% for brilliant green, Congo red, and crystal violet, respectively. Based on the kinetic and isotherm models, the presence of a large number of surface hydroxyl groups on the surface of the material and OH- ions in solutions generated by water splitting was found to be responsible for the complete decolorization of all of the dyes. Adsorption of chemically diverse dyes by the nanoporous, eco-friendly, ferromagnetic, economic, and reusable Li-MgF provides a sustainable and easy way to treat textile industry effluents in large amounts.

Development of a low-cost photocatalytic aerogel based on cellulose, carbon nanotubes, and TiO2 nanoparticles for the degradation of organic dyes

A hybrid ultra-light and porous cellulose aerogel was prepared by extracting cellulose fibers from white paper, alkali/urea as a crosslinker agent, and functionalized with CNTs and pure anatase TiO2 nanoparticles. Since CNTs work as mechanical reinforcement for aerogels, physical and mechanical properties were measured. Besides, since TiO2 acts as a photocatalyst for degrading dyes (rhodamine B and methylene blue), UV-Vis spectroscopy under UV light, visible light, and darkroom was used to evaluate the degradation process. XRD, FTIR, and TGA were employed to characterize the structural and thermal properties of the composite. The nanostructured solid network of aerogels was visualized in SEM microscopy confirming the structural uniformity of cellulose and TiO2-CNTs onto fibers. Moreover, CLSM was used to study the nano-porous network distribution of cellulose fibers and porosity, and the functionalization process in a detailed way. Finally, the photocatalytic activity of aerogels was evaluated by degradation of dye aqueous solutions, with the best photocatalytic removal (>97 %) occurring after 110 min of UV irradiation. In addition, HPLC-MS facilitated the proposed mechanism for the degradation of dyes. These results confirm that cellulose aerogels coupled with nanomaterials enable the creation of economic support to reduce water pollution with higher decontamination rates.

Enhanced catalytic reductive hydrogenation of an organic dye by Ag decorated graphitic carbon nitride modified MCM-41

Utilization of efficient, stable and reusable catalysts for wastewater treatment and catalytic elimination of toxic pollutants is a challenge among researchers. This present work shows the synthesis of high-surface-activity Ag nanoparticle decorated gC3N4 modified MCM-41 and its efficiency towards catalytic hydrogenation of organic dye in the presence of reducing agent NaBH4. The proposed mechanism is based on the transfer of H+ and 2e- between the dye and the catalyst. Adsorption of dye stuff on the catalyst is a rate-determining step and is accelerated by the MCM-41 support which enhances the surface area. The catalytic efficiency and optimum time requirement were examined through the adsorption-desorption equilibrium, pseudo-first-order reaction kinetic model for the dye. The result obtained was 98% catalytic efficiency followed by the catalytic hydrogenation reaction.

The Impact of Metal and Heavy Metal Concentrations on Vancomycin Resistance in Staphylococcus aureus within Milk Produced by Cattle Farms and the Health Risk Assessment in Kurdistan Province, Iran

In today's food landscape, the paramount focus is on ensuring food safety and hygiene. Recognizing the pivotal role of the environment and its management in safeguarding animal products, this study explores vancomycin resistance in raw milk from livestock farms in the Kurdistan province and its correlation with metal and heavy metal. One hundred and sixty raw milk samples were collected from various locations, with heavy metal concentrations analyzed using ICP-MS. Identification of Staphylococcus aureus and vancomycin resistance testing were conducted through culture and the Kirby-Bauer method. This study investigates the relationship between resistance and heavy metal levels, revealing that 8.75% of milk samples contained Staphylococcus aureus, with 28.58% exhibiting vancomycin resistance. Significant variations in arsenic, iron, zinc, sodium, and aluminum concentrations were observed between resistant and sensitive samples (p < 0.01). The increase in arsenic, iron, and aluminum, along with the decrease in zinc, demonstrated a significant association with vancomycin resistance (p < 0.001). Levels of lead, cadmium, mercury, zinc, and iron exceeded permissible limits (p < 0.05). The Target Hazard Quotient (THQ) for cadmium indicated a high non-carcinogenic risk, while the Target Risk (TR) for arsenic fell within the carcinogenic range. Accumulation of heavy metals has the potential to impact antibiotic resistance in milk, underscoring the imperative to control arsenic residues for national safety.

Furan-Dihydroquinazolinone Based Fluorescent Nanoprobe for Selective Recognition of 4-Nitrophenol: A Spectofluorimetric Approach

Fluorescent organic nanoparticles (FONPs) have attracted much attention as a practicable and effective platform for detection applications. The present article describes the preparation of FONPs derived from the quinazolinone-based 2-(furan-2-yl)-2,3-dihydroquinazolin-4(1H)-one derivative FHDQ. Self-assembly of FHDQ in an aqueous medium resulted in the formation of FONPs through H-type aggregation and showed excellent fluorescence properties. The presence of other coexisting species solutions did not affect the selective fluorescence quenching observed with the addition of 4-nitrophenol (4-NP). The photophysical properties, i.e., UV-Vis absorbance, fluorescence emission, and lifetime measurements together with zeta particle sizer, support excited-state complex formation followed by a dynamic fluorescence quenching phenomenon in the emission of FDHQNPs. In the concentration range of 0 to 36 μg.[Formula: see text], the detection limit of this turn-off sensor FDHQNPs against 4-NP was determined to be 0.01611 μM. Finally, the practicability of the FDHQNPs for the analysis of 4-NP in environmental samples was demonstrated.