Facile green synthesis of zero-valent iron nanoparticles using barberry leaf extract (GnZVI@BLE) for photocatalytic reduction of hexavalent chromium

Physalis peruviana heteropolysaccharide-conjugated selenium nanoparticles: Preparation, characterization, and promising applications in cancer therapy

Selenium nanoparticles (SeNPs) have attracted considerable attention in the field of cancer therapy due to their remarkable biological activities and advantageous nanoscale properties. However, their inherent instability presents a considerable challenge for broader applications. To address this issue, the heteropolysaccharide extracted from golden berries (the fruits of Physalis peruviana), designated as DLG, was utilized to synthesize heteropolysaccharide-conjugated selenium nanoparticles, named DLG-SeNP3. Subsequent characterization showed that the nanoparticles DLG-SeNP3 were spherical, with an average particle size of 77 nm, a zeta potential of -14.4 mV, and excellent stability under physiological pH conditions. Further biological investigations showed that DLG-SeNP3 effectively inhibited tumor cell proliferation, exhibiting an IC50 value of 41.60 μg/mL against A549 cells, and induced apoptosis, with a proportion of 31.30 % at 100 μg/mL. Moreover, in vivo experiments demonstrated that DLG-SeNP3 not only inhibited angiogenesis, resulting in a 26.51 % decrease at 2 μg/mL, but also suppressed tumor growth and invasion, with reductions of 76.90 % and 66.67 % in the intensity and foci of red fluorescence, respectively, at 2 μg/mL. In conclusion, DLG-SeNP3, stabilized with polysaccharides derived from golden berries, shows promising potential for application in cancer treatment.

Application of Fourier Transform Infrared (FTIR) Spectroscopy in Characterization of Green Synthesized Nanoparticles

The fundamental principle of Fourier Transform Infrared (FTIR) spectroscopy is based on the vibration and rotation of atoms, and it has become a universal and widely used spectral methodology for the detection of internal molecular structures in a diverse range of fields. A considerable number of review articles pertaining to the applications of FTIR spectroscopy have been published in recent years. Nevertheless, a comprehensive summary of the application of FTIR spectroscopy in nanoparticles' (NPs') green synthesis has yet to be presented. In the present paper, we propose a series of case studies that demonstrate the application of FTIR spectroscopy in the analysis of metal and metal oxide NPs that have been synthesized using green synthesis processes. Furthermore, a summary is presented of the position of functional group bands in FTIR spectra that are responsible for the reduction, capping and stabilization of NPs. In this review, we explore the advantages and limitations of FTIR and propose methodologies for overcoming these challenges. We also present potential solutions for the analysis of complex FTIR spectra. The present summary is intended to serve as a compendium of information for researchers engaged in the field of green synthesis of NPs, utilizing FTIR spectroscopy as a research tool.

Eco-friendly synthesis of gold nanoparticles via tangerine peel extract: Unveiling their multifaceted biological and catalytic potentials

Recent advancements in nanoscience underscore the transformative potential of nanomaterials in environmental and biological applications. In this study, we synthesized gold nanoparticles (Au@TPE NPs) using an eco-friendly and cost-effective approach, leveraging tangerine peel extract as both a capping and reducing agent. This method presents a sustainable alternative to traditional chemical agents. We optimized synthesis parameters, including time (5, 30, 60, and 90 min), temperature (25, 40, and 60 °C), and gold concentration (5, 10, 15, and 20 mM) to refine the nanoparticles size and morphology. Characterization via UV-Vis, XRD, FT-IR, EDAX, FESEM, and TEM revealed that nanoparticles synthesized at 40 °C and 15 mM gold concentration exhibited an optimal size (∼26 ± 5 nm) and a spherical shape. The Au@TPE NPs demonstrated antibacterial activity against both Gram-positive and Gram-negative bacteria, with minimum inhibitory concentrations (MIC) of 31.25 μg/ml for Klebsiella pneumoniae and Escherichia coli, and 62.5 μg/ml for Pseudomonas aeruginosa. Notably, they also exhibited antifungal activity against Candida albicans and demonstrated 92.7 % antioxidant activity in a DPPH scavenging assay at 250 μg/ml. Photocatalytic tests revealed that the nanoparticles effectively degraded methyl orange and rhodamine B, achieving 88.6 % and 93.2 % degradation under UV light, respectively, and 67.3 % and 74.1 % degradation under sunlight. These promising biological and catalytic properties suggest significant potential for diverse applications.

Green synthesis and characterization of iron nanoparticles synthesized from bioflocculant for wastewater treatment: A review

Nanotechnology is a rapidly expanding field with diverse healthcare, agriculture, and industry applications. Central to this discipline is manipulating materials at the nanoscale, particularly nanoparticles (NPs) ranging from 1 to 100 nm. These NPs can be synthesized through various methods, including chemical, physical, and biological processes. Among these, biological synthesis has gained significant attention due to its eco-friendly nature, utilizing natural resources such as microbes and plants as reducing and capping agents. However, information is scarce regarding the production of iron nanoparticles (FeNPs) using biological approaches, and even less is available on the synthesis of FeNPs employing microbial bioflocculants. This review aims to provide a comprehensive examination of the synthesis of FeNPs using microbial bioflocculants, highlighting the methodologies involved and their implications for environmental applications. Recent findings indicate that microbial bioflocculants enhance the stability and efficiency of FeNP synthesis while promoting environmentally friendly production methods. The synthesized FeNPs demonstrated effective removal of contaminants from wastewater, achieving removal rates of up to 93 % for specific dyes and significant reductions in chemical oxygen demand (COD) and biological oxygen demand (BOD). Additionally, these FeNPs exhibited notable antimicrobial properties against both Gram-positive and Gram-negative bacteria. This review encompasses studies conducted between January 2015 and December 2023, providing detailed characterization of the synthesized FeNPs and underscoring their potential applications in wastewater treatment and environmental remediation.

Remediation of Cr(VI) Polluted Groundwater Using Zero-Valent Iron Composites: Preparation, Modification, Mechanisms, and Environmental Implications

The extensive application of chromium (Cr) in many industries has inevitably resulted in the release of Cr(VI) into the groundwater environment, thus posing damage to the ecosystem and human health. Nano zero-valent iron (nZVI) has been widely studied and applied in the remediation of Cr(VI)-contaminated water as an ideal material with high reductive capacity, which enables the transformation of teratogenic and carcinogenic Cr(VI) into less toxic Cr(III). This review comprehensively summarizes the preparation and modification methods of nZVI Cr(VI) removal performance and mechanisms by nZVI and modified nZVI materials. The field applications of nZVI-based materials, such as combining the injection well and the permeable reactive barrier (PRB) to remove Cr(VI) in groundwater, have been reported. Subsequently, the potential toxicity of nZVI-based materials to organisms during environmental application has been highlighted in the current study. Finally, the review outlines potential improvements and explores future directions for the use of nZVI-based materials in groundwater contamination remediation.

Core to concept: synthesis, structure, and reactivity of nanoscale zero-valent iron (NZVI) for wastewater remediation

Numerous technological advancements have been developed to tackle the issue of wastewater remediation effectively. However, the practical application of these technologies on a large scale has faced several challenges that have hindered their progress. These challenges include low selectivity, high energy requirements, and significant expenses. Nanoscale materials have demonstrated remarkable effectiveness in removing a wide range of contaminants. Nanoscale zero-valent iron (NZVI) exhibits a range of distinctive physical and chemical properties that have proven to be highly effective in various environmental remediation applications. These include its impressive surface area, remarkable reactivity, and its capacity to create stable colloidal suspensions. The paper explores the synthetic techniques for NZVI with special emphasis on green synthesis and the use of capping or support agents for maintaining stability and enhancing the reactivity of NZVI. The various structural and reactivity aspects of NZVI have been highlighted for its potential application in wastewater treatment sequestrating various categories of inorganic and organic contaminants. The discussion also delves into the limitations of NZVI, highlighting its dependence on water as a medium for contact reaction or electron transfer through the action mechanism of NZVI in adsorptive and photocatalytic sequestration of contaminants. The beneficial potential of NZVI-based composite systems in the field of environmental remediation has also been included which aids in the application of NZVI in environmental remediation.

Green low-cost synthesis of zero-valent iron nanoparticles from Palm Petiole Extract for Cr(VI) removal from water

One of the hottest research topics over the last decades was the valorization or/and recycling of agro-industrial wastes into different valuable liquid or solid products, which is considered a sustainable and low-cost approach. In this study, we developed zero-valent iron nanoparticles from Palm Petiole Extract (P-NZVI) using a green and straightforward approach. The as-synthesized P-NZVI was used to adsorb Cr(VI) in water. The physico-chemical characterizations of P-NZVI, including the particle size, crystalline structure, surface area, morphology, and functional groups, were investigated via several techniques such as UV-vis spectroscopy, SEM, TEM, XRD, FTIR, AFM, DLS, pHZPC measurement, and BET analysis. The adsorption performance of P-NZVI was studied under different operational parameters, including pollutant concentration, pH, temperature, and adsorbent mass. The adsorption rate was found to be 89.3% within 40 min, corresponding to the adsorption capacity of 44.47 mg/g under the following conditions: initial Cr(VI) concentration of 40 mg/L, pH 5, and a P-NZVI dosage of 1 g/L. It was found that the adsorption pattern follows the Langmuir and the pseudo-second-order kinetic models, indicating a combination of monolayer adsorption and chemisorption mechanisms. The thermodynamic study shows that the adsorption process is endothermic and spontaneous. The reusability of P-NZVI was carried out four times, showing a slight decrease from 89.3 to 87%. These findings highlight that P-NZVI's could be an effective green adsorbent for removing Cr(VI) or other types of toxic pollutants from water.

Green synthesis of iron nanoparticles using mulberry leaf extract: characterization, identification of active biomolecules, and catalytic activity

The synthesis of iron-based nanoparticles (Fe NPs) using traditional preparation methods suffered from the disadvantages of high cost, environmental harm, and easy agglomeration. In this study, a novel eco-friendly method was proposed for the synthesis of iron nanomaterials (ML-Fe NPs): using antioxidant components extracted from mulberry leaf to reduce divalent iron (II). The preparation conditions of ML-Fe NPs were optimized by orthogonal tests. The prepared ML-Fe NPs exhibited an amorphous core-shell structure, displaying excellent dispersion and stability. During the synthesis process of ML-Fe NPs, the polyphenol molecules in mulberry leaf extract played a dominant role. A possible synthetic mechanism involving complexation, reduction, and encapsulation was proposed. Furthermore, the ML-Fe NPs were utilized to construct an ML-Fe NPs/peroxymonosulfate catalytic system for the degradation of Rhodamine B dye wastewater. The ML-Fe NPs demonstrated remarkable catalytic potential, achieving a 99% degradation efficiency for Rhodamine B within a span of 40 min.

Removal of water pollutants using plant-based nanoscale zero-valent iron: A review

Nanotechnology has been increasingly explored for the treatment of various waste streams. Among different nanoparticles, nanoscale zerovalent iron (nZVI) has been extensively investigated due to its high reactivity and strong reducing power. However, conventional methods for the synthesis of nZVI particles have several limitations and led to the green synthesis of nZVI using plant-based materials. Plant extracts contain various reducing agents that can be used for nZVI synthesis, eliminating the need for toxic chemicals, and reducing energy consumption. Additionally, each plant species used for nZVI synthesis results in unique physicochemical properties of the nanoparticles. This review paper provides an overview of plant-based nZVI particle synthesis, its characteristics, and its application for the removal of different classes of pollutants such as dyes, heavy metals, nutrients, and trace organic pollutants from water. The review shows that continued research on plant-based nZVI particles to fully understand its potential in wastewater treatment, especially for the removal of a wider variety of pollutants, and for improving sustainability and reducing the cost and environmental impact of the process, is necessary.

Recycling of polluted dredged sediment - Building new materials for plant growing

The worldwide concern is caused by a large quantity of dredged sediment. The issue becomes more severe when contaminated sediment has to be landfilled. Therefore, researchers involved in the dredged sediment management are increasingly motivated to improve circularity in sediment management processes. Prior to the dredged sediment usage in agriculture, its necessary to confirm conclusively its safety in the context of trace elements (TEs) levels. This study reports the use of different solidification/stabilization (S/S) sediment amendments (cement, clay, fly ash and green synthetized nano-zerovalent iron-nZVI) to remediate dredged sediment. The aim was to identify the effects of applied sediment S/S treatments on the growth and development of Brassica napus. The results showed that in all S/S mixtures TEs levels in the highly labile and bioavailable fraction were significantly decreased (less than 10%, while untreated sediment contained up to 36% of TEs). Simultaneously, the highest share of metals (69-92%) was in the residual fraction, which is considered as chemically stable and biologically inert fraction. Nevertheless, it was noticed that different S/S treatments trigger plants' functional traits indicating that plants' establishment in S/S treated sediment can be limited to certain extent. Besides, based on primary and secondary metabolites (elevated specific leaf area along with declined malondialdehyde content) it was concluded that Brassica plants employ a conservative resource use strategy aiming to buffer phenotypes against stress condition. Lastly, it was inferred that among all analyzed S/S treatments, green synthetized nZVI from oak leaves can effectively promote TEs stabilization in dredged sediment, concurrently enabling plant's establishment and fitness.

ZnCo2O4 composite catalyst accelerated removal of phenylic contaminants containing of Cr(VI) in dielectric barrier discharge reactor: Process and mechanism study

The degradation of phenylic contaminants (phenol, hydroquinone, nitrobenzene, p-nitrophenol) containing Cr(VI) has been investigated in a dielectric barrier discharge (DBD) system using a ZnCo₂O₄ composite catalyst. The ZnCo₂O₄ nanowires combined with multi-walled carbon nanotubes (MWNTs) on a sponge substrate in the discharge system can induce a decrease in the corona inception voltage and discharge becomes more stable resulting in an improvement in the energy utilization efficiency. With the synergistic degradation of phenylic species containing Cr(VI), the total elimination efficiency was further improved. The active substances (H₂O₂ and O₃) were detected in the discharged solution, and some of them were consumed in the phenylic system. The effects of ·OH, O₂·^- and e^- were also verified using free radical trapping experiments in which ·OH exhibited the main oxidation effect for the degradation of phenylic pollutants, and e^-, H₂O₂ and H· affect the reduction of Cr(VI). The intermediate products were determined in order to analyze the degradation process of phenylic pollutants by the ZnCo₂O₄ composite catalyst in combination with the DBD system. The electron transfer process in the ZnCo₂O₄ composite catalyst during discharge was analyzed. Finally, the biotoxicity of the phenylic pollutants before and after degradation was compared.

Effective and reproducible biosynthesis of nanogold-composite catalyst for paracetamol oxidation

Pharmaceutical products are some of the most serious emergent pollutants in the environment, especially nowadays of the COVID-19 pandemic. In this study, nanogold-composite was prepared, and its catalytic activity for paracetamol degradation was investigated. Moreover, for the first time, recycled waste diatomite earth (WDE) from beer filtration was used for reproducible gold nanoparticle (Au NPs) preparation. We studied Au NPs by various psychical-chemical and analytical methods. Transmission and scanning electron microscopy were used for nanogold-composite morphology, size and shape characterization. Total element concentrations were determined using inductively coupled plasma mass and X-ray fluorescence spectrometry. X-ray powder diffraction analysis was used for crystal structure characterization of samples. Fourier transform infrared spectrometer was used to study the chemical changes before and after Au NP formation. The results revealed that the WDE served as both a reducing and a stabilizing agent for crystalline spherical 30 nm Au NPs as well as acting as a direct support matrix. The kinetics of paracetamol degradation was studied by high-performance liquid chromatography with a photodiode array detector. The conversion of paracetamol was 62% and 67% after 72 h in the absence or presence of light irradiation, respectively, with 0.0126 h^-1 and 0.0148 h^-1 reaction rate constants. The presented study demonstrates the successful use of waste material from the food industry for nanogold-composite preparation and its application as a promising catalyst in paracetamol removal.

Biochar-supported nZVI for the removal of Cr(VI) from soil and water: Advances in experimental research and engineering applications

Over the past decade, biochar-supported nZVI composites (nZVI/biochar) have been developed and applied to treat various pollutants due to their excellent physical and chemical properties, especially in the field of chromium (VI) removal. This paper reviewed the factors influencing the preparation and experiments of nZVI/biochar composites, optimization methods, column experimental studies and the mechanism of Cr(VI) removal. The results showed that the difference in raw materials and preparation temperature led to the difference in functional groups and electron transfer capabilities of nZVI/biochar materials. In the experimental process, pH and test temperature can affect the surface chemical properties of materials and involve the electron transfer efficiency. Elemental doping and microbial coupling can effectively improve the performance of nZVI/biochar composites. In conclusion, biochar can stabilize nZVI and enhance electron transfer in nZVI/biochar materials, enabling the composite materials to remove Cr(VI) efficiently. The study of column experiments provides a theoretical basis for applying nZVI/biochar composites in engineering. Finally, the future work prospects of nZVI/biochar composites for heavy metal removal are introduced, and the main challenges and further research directions are proposed.

Plant-Derived Iron Nanoparticles for Removal of Heavy Metals

Nanoparticle synthesis has seen exponential development recently as its characteristics of high surface area, high rate of adsorption, and easy, cost-effective synthesis have been exploited for the purpose of ground water purification via the removal of organic and inorganic compounds, along with the removal of heavy metals and microbes. The synthesis of Zero-Valent Iron Nanoparticles (ZVI NPs) by green methods has proved to be environmentally friendly in many ways as it employs the use of naturally occurring plant extracts. These nanoparticles have large surface areas and efficiently remove heavy metals. The reducing potential of these ZVI NPs is mostly −0.44 V, thus allowing them to reduce heavy metal compounds such as cadmium, lead, zinc, copper, and arsenic present in wastewater. Irradiated nanoparticles have also exhibited antimicrobial resistance and adsorption. It is also observed that nanoparticles show a higher rate of efficacy at a lower pH. The adsorbent, which is ZVI NPs in this case, when present in large doses reduces heavy metal compounds rapidly and effectively.

Influence of the Alcoholic/Ethanolic Extract of Mangifera indica Residues on the Green Synthesis of FeO Nanoparticles and Their Application for the Remediation of Agricultural Soils

The green synthesis of iron oxide nanoparticles (FeO NP) has been investigated using the extract in absolute ethanolic and alcoholic solvents 96% from the peel of the mango fruit (Mangifera indica), thus evaluating the influence of the type of solvent on the extraction of reducing metabolites. A broad approach to characterization initially controlled by UV-vis spectrophotometry has been directed, the formation mechanism was evaluated by Fourier transform infrared spectroscopy (FTIR), the magnetic properties by characterization by Physical Property Measurement System (PPSM), in addition to a large number of techniques such as X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (DRX), transmission electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and Z potential to confirm the formation of FeO NP. The results suggest better characteristics for FeO NP synthesized using 96% alcoholic solvent extract. The successful synthesis was directly proven in the removal of metals (Cr-VI, Cd, and Pb) as a potential alternative in the remediation of agricultural soils.

Mechanistic study of Cr (VI) removal by modified alginate/GO composite via synergistic adsorption and photocatalytic reduction

A novel composite material was prepared by blending graphene oxide into polyethyleneimine grafted sodium alginate. The synthesized material was investigated as adsorbent and photocatalyst for the removal of hexavalent chromium (Cr (VI)) from aqueous solutions. The composite material has shown remarkable removal efficiency for Cr (VI) in high initial concentration solutions as the removal rate reached 86.16% and 99.92% for adsorption and photoreduction, respectively. We discovered experimentally that the adsorption was dominated via electrostatic interaction while the blending of GO could contribute in stimulating electrons for the photoreduction process. Moreover, the photoreduction can alter the surface charge of chromium species, thus electrostatic repulsion could regenerating the active sites of composite spontaneously. The conduction band energy was calculated as -2.04 eV, which proved that blending GO can narrow the bandgap of the composite material, thus enhance the light response and the photoreduction ability towards Cr (VI).