Zinc Oxide Nanoparticles and Their Application in Adsorption of Toxic Dye from Aqueous Solution

Synthesis of GO-SiO2/ZnO/Fe3O4 nano adsorbent for preconcentration of aflatoxins in food samples using SPE-HPLC-FLD method

This study demonstrates a new extraction method for determination of aflatoxins (AFs) in food samples by a GO-SiO2/ZnO/Fe3O4 nanocomposite as new and effective sorbent. The nanocomposite structure was confirmed by FT-IR, XRD, EDX, FE-SEM, TEM, and mapping techniques. Optimization of the extraction process was conducted by investigating pH, adsorbent amount, sample volume, and solvent volume using central composite design (CCD). The method showed good linearity for AFs B1, B2, G1, and G2 within specified ranges. Detection and quantification limits were 0.06-0.53 and 0.20-1.62 ng mL-1, respectively. The high performance liquid chromatography with fluorescence detector assisted by solid phase extraction (SPE-HPLC-FLD) method was applied to food samples, achieving recoveries of 70.15-97.08 %. Accuracy was confirmed through recovery measurements in spiked samples, with ranges of 70.15-97.85 % in wheat, 70.01-91.97 % in chickpeas, and 71.29-93.92 % in white pepper. Reusability and cost-effectiveness suggest its potential for preconcentration and determination of AFs in food samples.

Synthesis and Characterization of MO:ZnO/Fe2O3 Nanocomposite and Its Effectiveness in the Degradation of Green Malachite Dye: Molecular Dynamics and Electronic Properties Study of Green Malachite Adsorption

Nanocomposites have attracted significant attention from researchers due to their remarkable chemical, adsorptive, and thermal properties. This work focuses on the synthesis of the montmorillonite modified with octadecylamine (MO):ZnO/Fe2O3 (MO:ZnO/Fe2O3) nanocomposite. The ZnO/Fe2O3 nanocomposite and MO were mixed in solution to create the component. XRD, FTIR, BET, TEM, MEB, and UV-vis were used to characterize the materials. In terms of their textural, morphological, and structural characteristics, interesting results were found. After 30 min of sunlight exposure, 96.12% of the GM dye can be degraded using just 0,02 g of MO:ZnO/Fe2O3 (1:2(1/0.05)). In contrast, ZnO NPs exhibited the highest percentage of degradation under UV light, achieving 91.85%. The greater efficiency of MO:ZnO/Fe2O3 under sunlight is attributed to its narrower band gap of 2.25 eV, which enables better utilization of visible light. Next using the Forcite and CASTEP modules in the Material Studio software, the GM dye's adsorption behavior on the surface of the as-prepared nanocomposite was analyzed. The results demonstrate that the GM/MO interaction is of the chemisorption type, predominantly governed by hydrogen bonding, electrostatic interactions, and π-π interactions between GM molecules. The ZnO (100) surface exhibits the highest density of active sites for GM degradation via a chemisorption adsorption process. Molecular dynamics simulations at 289.15 K reveal that the redox processes responsible for the degradation of the GM pollutant and its conversion into CO2 gas are exothermic. For ZnO, the electronic properties yield a band gap of 2.686 eV. For GM/ZnO (100) and GM/ZnO (101), the band gaps were determined to be 0.291 and 2.704 eV, respectively, by using a 340 eV cutoff energy and the GGA RPBE pseudofunctional.

Study of methylene blue removal and photocatalytic degradation on zirconia thin films modified with Mn-Anderson polyoxometalates

Recalcitrant pollutants are challenging to degrade during water treatment processes. Methylene blue (MB), a cationic dye, is particularly resistant to degradation and is environmentally persistent. Heterogeneous photocatalysis has emerged as a suitable strategy for removing such pollutants from water. In this work, ZrO2 thin films were modified with Anderson-type Mn-polyoxometalate (MnPOM) ((NH4)3[MnMo6O24H6]), and the efficiency of MB removal from water was studied. ZrO2 was synthesized by a sol-gel method, with thin films deposited using the doctor blade method, and ZrO2 thin films were modified using chemisorption method. The synthesized materials were characterized using SEM, EDX, UV-Vis diffuse reflectance spectroscopy and FTIR. The adsorption kinetics and isotherms for MB were studied for both bare ZrO2 and ZrO2/MnPOM composites. Optical characterization showed a band gap energy of 4.02 eV for bare ZrO2, while the ZrO2/MnPOM composite exhibited a band gap of 3.7 eV. Furthermore, ZrO2 showed lower MB removal capacity (∼8%) than ZrO2/MnPOM thin films (∼29%). The isothermal adsorption studies indicated that MB adsorption onto both bare ZrO2 and ZrO2/MnPOM followed the Langmuir adsorption model (qm = 20.6 mg g-1 for ZrO2 and qm = 62.9 mg g-1 for ZrO2/MnPOM). Furthermore, the adsorption kinetics of MB were well described by a pseudo-second-order model. Photocatalytic testing under UV irradiation showed an apparent rate constant (kap) of 2 × 10-3 min-1 for bare ZrO2 and a value of kap 5.4 × 10-3 min-1 for ZrO2/MnPOM after 100 minutes. TD-DFT calculations revealed an LMCT interaction between the ZrO2 nanoparticle and the MnPOM, which likely contributes to the enhanced photocatalytic activity of the ZrO2/MnPOM composite.

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.

Green synthesis of zinc oxide nanoparticles using Padina pavonica extract for efficient photocatalytic removal of methylene blue

Dye-laden wastewater poses a significant environmental and health threat. This study investigated the potential of green-synthesized zinc oxide nanoparticles (ZnO NPs), derived from Padina pavonica brown algae extract, for the removal of methylene blue (MB) dye. The hypothesis was that utilizing algal extract for ZnO NP synthesis would enhance adsorption capacity and photocatalytic activity for dye removal. The synthesized ZnO NPs, characterized by Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Zeta Potential, demonstrated high adsorption capacity (Qm = 192.308 mg g-1) and excellent removal efficiency (> 98%) for MB at low dye concentrations. Langmuir isotherm and pseudo-second-order kinetic models best fit the experimental data, suggesting monolayer adsorption and chemisorption as the primary mechanisms. Notably, the green ZnO NPs exhibited greater photocatalytic activity under direct sunlight irradiation compared to other light sources. Additionally, these nanoparticles displayed antimicrobial properties against various bacteria, indicating potential for water disinfection. This research offers a sustainable and environmentally friendly approach for wastewater treatment utilizing green ZnO NPs for efficient dye removal and potential water disinfection applications.

Catalytic degradation of aromatic dyes using triazolidine-thione stabilized nickel nanoparticles

Nanoparticles have been extensively studied for many years due to their important roles in catalysis, metallurgy and high temperature superconductors. But, Nanoparticles are extremely unstable and easily react with other substances. So, to control the size and the shape of nanoparticles they must be stabilized. Organic Ligands have gain more attention for stabilizing Nanoparticles. In the present work, Nickel Nanoparticles have been synthesized by reduction method and then stabilized by synthesized 5-phenyl triazolidine-thione based organic ligand to achieve larger surface area and good catalytic activity. Stabilized Nickel NPs of different ratios were synthesized for analyzing their catalytic performance against dyes that has become one of the most serious environmental problem causing drastic water pollution. The prepared thione stabilized Nickel nanoparticles were confirmed by UV-Visible and Infrared Spectroscopy. UV/Vis analysis displayed the peak at 236 nm which confirms the metallic Ni NPs formation while, in FTIR peak around 720-750 cm-1 is due to the nickel and sulphur bond stretching vibrations. The size, surface morphology and the quality of the stabilized Ni Nanoparticles were analyzed by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis. SEM images showed uneven morphology with variously sized and shaped particles. Large surface area is visible which is advantageous for catalytic degradation of pollutants. The degradation process was studied by using UV-visible Spectroscopy. The catalytic behavior of stabilized nanoparticles was evaluated by using various parameters i.e. time, concentration and size of NPs. These parameters were optimized during degradation process to get maximum degradation in short period of time. Maximum percentage degradation of Methylene blue, Methyl Orange and Rhodamine B dyes were achieved up to 90 %, 88 % and 81 % respectively, in short duration of time. All the three ratios of thione stabilized Ni Nanoparticles showed good degrading performance for all dyes, but 1:2 thione stabilized Ni NPs had shown maximum catalytic performance.

Metallic nanoparticles unveiled: Synthesis, characterization, and their environmental, medicinal, and agricultural applications

Metallic nanoparticles (MNPs) have attracted great interest among scientists and researchers for years due to their unique optical, physiochemical, biological, and magnetic properties. As a result, MNPs have been widely utilized across a variety of scientific fields, including biomedicine, agriculture, electronics, food, cosmetics, and the environment. In this regard, the current review article offers a comprehensive overview of recent studies on the synthesis of MNPs (metal and metal oxide nanoparticles), outlining the benefits and drawbacks of chemical, physical, and biological methods. However, the biological synthesis of MNPs is of great importance considering the biocompatibility and biological activity of certain MNPs. A variety of characterization techniques, including X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, scanning electron microscopy, dynamic light scattering, atomic force microscopy, Fourier transform infrared spectroscopy, and others, have been discussed in depth to gain deeper insights into the unique structural and spectroscopic properties of MNPs. Furthermore, their unique properties and applications in the fields of medicine, agriculture, and the environment are summarized and deeply discussed. Finally, the main challenges and limitations of MNPs synthesis and applications, as well as their future prospects have also been discussed.

Biogenic engineered zinc oxide nanoparticle for sulfur black dye removal from contaminated wastewater: comparative optimization, simulation modeling, and isotherms

This research work aimed to isolate and culture the bacterium Bacillus paramycoides for biogenic fabrication of zinc oxide nanoparticles, specifically ZnO and ZnO-ME nanoparticles (nanoparticles fabricated from bacterial extracts only - ZnO, and from bacterial cell mass including extract - ZnO-ME). SEM investigation revealed the spherical-shaped NPs with 22.33 and 39 nm in size for ZnO and ZnO-ME, respectively. The Brunauer, Emmett, and Teller (BET) studies revealed mesoporous structure with pore diameters of 13.839 and 13.88 nm and surface area of 7.617 and 33.635 m2/gm for ZnO and ZnO-ME, respectively. Various parameters for the adsorption of sulfur black dye onto both ZnO and ZnO-ME were screened and optimized using Plackett-Burman Design (PBD), Full Factorial Design (FFD) and Central Composite Design (CCD). The results of the optimization modeling study revealed that FFD yielded the most predictable and best-fitting results among all the models studied, with R2 values of 0.998 for ZnO and 0.993 for ZnO-ME. Notably, ZnO-ME exhibited a greater dye removal efficiency 80% than ZnO i.e., 71%, it may be due to the presence of amorphous carbon on the surface of ZnO-ME. Among the various isothermal models, the Freundlich model displayed the strongest correlation with the dye removal data, confirming the multilayer adsorption of dye on both nanoparticles and supporting physisorption. Therefore, ZnO and ZnO-ME nanoparticles have been proven as potential tools for mitigating environmental impacts associated with dye-containing wastewater.

MgO Nanoparticles as a Promising Photocatalyst towards Rhodamine B and Rhodamine 6G Degradation

The increasing global requirement for clean and safe drinking water has necessitated the development of efficient methods for the elimination of organic contaminants, especially dyes, from wastewater. This study reports the synthesis of magnesium oxide (MgO) nanoparticles via a simple precipitation approach and their thorough characterization using various techniques, including XRD, FT-IR, XPS, TGA, DLS, and FESEM. Synthesized MgO nanoparticles' photocatalytic effectiveness was evaluated towards rhodamine B and rhodamine 6G degradation under both UV and visible light irradiation. The results indicated that the MgO nanoparticles possess a face-centered cubic structure with enhanced crystallinity and purity, as well as an average crystallite size of approximately 3.20 nm. The nanoparticles demonstrated a significant BET surface area (52 m2/g) and a bandgap value equal to 5.27 eV. Photocatalytic experiments indicated complete degradation of rhodamine B dye under UV light within 180 min and 83.23% degradation under visible light. For rhodamine 6G, the degradation efficiency was 92.62% under UV light and 38.71% under visible light, thus verifying the MgO catalyst's selectivity towards degradation of rhodamine B dye. Also, reusability of MgO was investigated for five experimental photocatalytic trials with very promising results, mainly against rhodamine B. Scavenging experiments confirmed that •OH radicals were the major reactive oxygen species involved in the photodegradation procedure, unraveling the molecular mechanism of the photocatalytic efficiency of MgO.

Photocatalytic degradation of methyl blue dye with H2O2 sensing

A condensation polymer (urea-formaldehyde resin) passivated ZnO nanoparticles were used as an efficient photocatalyst for methyl blue degradation in the presence of H2O2 involving a Fenton-like reaction. The formation of OH˙ radicals were attributed to the pivotal factor for the degradation process. The method was easy and recyclable. The dose of photocatalyst, initial dye concentration, pH variation, variations of the composition of the photocatalyst, and the effect of scavengers were gauged. The degraded product was highly fluorescent and fluorometric detection of H2O2 was achieved along with a colorimetric recognition pathway. No other dye could be degraded under similar experimental conditions, implying the novel utility of methyl blue for environmental remediation.

Adsorptive removal of Safranine T dye from aqueous solutions using sodium alginate-Festuca arundinacea seeds bio-composite microbeads

In this study, composite microbeads were prepared using Festuca arundinacea seeds and sodium alginate biopolymer at different ratios and utilized as sorbents for the sorption of Safranine T from wastewater. The sorbents were characterized by FTIR, SEM, XRD, and BET analysis. According to BET analysis, the specific surface area of the adsorbents was calculated to be 10.99 m2/g and the surface was found to be mesoporous. The optimum conditions for adsorption studies including initial pH (2-12), concentration (10-50 mg/L), contact time (0-150 min), and adsorbent mass (0.05 g/50 mL-0.25 g/50 mL) were determined at 25 °C. The raw data obtained from sorption tests were applied to Freundlich, Langmuir-1, Langmuir-2, Langmuir-3, Langmuir-4, Temkin, Toth, and Koble-Corrigan isotherm models. The best results were obtained from the Langmuir-2 and accordingly the qm values were calculated as 454.54, 833.33, and 625.00 mg/g for FA, FA-SA-20, and FA-SA-30 at 25 °C, respectively. Adsorption kinetic data illustrated that the process followed the PSO model. Reusability and desorption studies were performed for composite microbeads. Additionally, the thermodynamic studies were performed at 25, 35 and 45 °C. Considering all these results, it was seen that the FA-SA-20 composite had the highest adsorption capacity and the best desorption efficiency.

Green Biosynthesis of Zinc Oxide Nanoparticles Using Pluchea indica Leaf Extract: Antimicrobial and Photocatalytic Activities

Nanotechnology is playing a critical role in several essential technologies with nanoscale structures (nanoparticles) in areas of the environment and biomedicine. In this work, the leaf extract of Pluchea indica was utilized to biosynthesize zinc oxide nanoparticles (ZnONPs) for the first time and evaluated for antimicrobial and photocatalytic activities. Different experimental methods were used to characterize the biosynthesized ZnONPs. The biosynthesized ZnONPs showed maximum Ultraviolet-visible spectroscopy (UV-vis) absorbance at a wavelength of 360 nm. The X-Ray diffraction (XRD) pattern of the ZnONPs exhibits seven strong reflection peaks, and the average particle size was 21.9 nm. Fourier-transform infrared spectroscopy (FT-IR) spectrum analysis reveals the presence of functional groups that help in biofabrication. The existence of Zn and O was confirmed by the Energy-dispersive X-ray (EDX) spectrum and the morphology by SEM images. Antimicrobial studies showed that the biosynthesized ZnONPs have antimicrobial efficacy against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Candida albicans and Cryptococcus neoformans where inhibition zones at concentration 1000 µg/mL were 21.83 ± 0.76, 13.0 ± 1.1, 14.9 ± 0.85, 24.26 ± 1.1, 17.0 ± 1.0, 20.67 ± 0.57 and 19.0 ± 1.0 mm respectively. Under both dark and sunlight irradiation, the photocatalytic activity of ZnONPs was evaluated towards the degradation of the thiazine dye (methylene blue-MB). Approximately 95% of the MB dye was broken down at pH 8 after 150 min of sunlight exposure. The aforementioned results, therefore, suggest that ZnONPs synthesized by implementing environmentally friendly techniques can be employed for a variety of environmental and biomedical applications.

Adsorption of direct blue 106 dye using zinc oxide nanoparticles prepared via green synthesis technique

Zinc oxide nanoparticles (ZnO-NPs) have in recent times shown effective adsorption capability for the confiscation of colour contaminants from aqueous environments (aquatic ecosystems or water bodies) due to the fact that ZnO contains more functional groups. Direct blue 106 (DB106) dye was selected for this present study as a model composite due to its wide range of uses in textiles (cotton and wools), woods, and paper industries, as well as their therapeutic applications, along with its potential for impairments. This study therefore focuses on the use of DB106 dye as a model composite due to its wide range of uses in textiles (cotton and wools), woods, and paper industries, as well as their therapeutic applications and their potential for impairments. Furthermore, the surface functionalization, shape, and composite pore size were revealed by TEM, FTIR, UV, and BET techniques. The current study uses green synthesis method to prepare ZnO-NPs as an adsorbent for the DB106 dye molecules adsorption under various conditions using the batch adsorption process. The adsorption of DB106 dye to the ZnO-NPs biosorbent was detected to be pH-dependent, with optimal adsorption of DB106 (anionic) dye particles observed at pH 7. DB106 dye adsorption to the synthesized ZnO-NPs adsorbent was distinct by means of the linearized Langmuir (LNR) and pseudo-second-order (SO) models, with an estimated maximum adsorption capacity (Qm) of 370.37 mg/g.

Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent-coated sand filter bed

This study aims to develop a chitosan-zinc oxide nano-adsorbent-coated sand (CZOCS) filter bed for getting rid of milk processing industry wastewater (MPIW) in a safe way. Chitosan zinc oxide nano-adsorbent (CZnO) of 88.35 ± 2.89 d.nm size was used to coat naturally available sand through a calcination process at 200 °C for a heating rate of 5 °C/min. The characteristics of the diffraction peaks and functional groups are attributed to the nature of CZnO loading on the sand surface. The increase in breakthrough and exhaustion times is caused by the biological oxygen demand (BOD) and chemical oxygen demand (COD) of influent having more time to interact with the adsorbent as bed height increases, resulting in higher reduction efficiencies. Lower bed heights (10 cm) which saturate faster than higher bed heights (40 cm) result in a shorter mass transfer time. Adsorption capacity at the 95% column exhaustion point increased from 611.04 to 1089.63 mg/g for BOD and from 4512.29 to 5600.81 mg/g for COD. Different kinds of kinetic models have been used to forecast breakthrough curves employing experimental data. Statistical and error function parameters were used to choose the best-fit model. Among the models investigated, the Thomas model was shown to be the best-fit with the highest R-square values of 0.9942 and 0.9939. The CZOCS has high reusability and could be used for up to six cycles of organic pollutant adsorption. Aside from that, novel CZOCS could be used to clean real MPIW, and making it one of the most promising adsorbents.

ZnO Nanoparticles from Different Precursors and Their Photocatalytic Potential for Biomedical Use

Semiconductor photocatalysts, particularly ZnO nanoparticles, were synthesized via the precipitation method using four different precursors (zinc acetate/zinc nitrate/zinc sulfate/zinc chloride) and compared, according to their optical, structural, photocatalytic, and anticancer properties. The materials were characterized via X-ray Diffraction method (XRD), micro-Raman, Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Dynamic Light Scattering (DLS), and Field Emission Scanning Electron Microscope (FESEM) analysis. Photocatalysis was conducted under UV and visible light irradiation, using Rhodamine B as the organic pollutant. It was observed that the highest photocatalysis efficiency was obtained by the nanoparticles synthesized from the zinc acetate used as precursor material. A cell-dependent anticancer efficiency of the tested ZnO nanoparticles was also observed, that was also attributed to the different precursors and the synthesis method, revealing that the nanoparticles that were synthesized from zinc acetate were more bioactive among the four tested precursors. Overall, the data revealed that both the enhanced photocatalytic and biological activity of ZnO nanoparticles derived from zinc acetate precursor could be attributed to the reduced crystalline size, increased surface area, as well as the observed hexagonal crystalline morphology.