Assessment of GO/ZnO nanocomposite for solar-assisted photocatalytic degradation of industrial dye and textile effluent

A review on existing and emerging approaches for textile wastewater treatments: challenges and future perspectives

This comprehensive review explores the complex environment of textile wastewater treatment technologies, highlighting both well-established and emerging techniques. Textile wastewater poses a significant environmental challenge, containing diverse contaminants and chemicals. The review presents a detailed examination of conventional treatments such as coagulation, flocculation, and biological processes, highlighting their effectiveness and limitations. In textile industry, various textile operations such as sizing, de-sizing, dyeing, bleaching, and mercerization consume large quantities of water generating effluent high in color, chemical oxygen demand, and solids. The dyes, mordants, and variety of other chemicals used in textile processing lead to effluent variable in characteristics. Furthermore, it explores innovative and emerging techniques, including advanced oxidation processes, membrane filtration, and nanotechnology-based solutions. Future perspectives in textile wastewater treatment are discussed in-depth, emphasizing the importance of interdisciplinary research, technological advancements, and the integration of circular economy principles. Numerous dyes used in the textile industry have been shown to have mutagenic, cytotoxic, and ecotoxic potential in studies. Therefore, it is necessary to assess the methods used to remediate textile waste water. Major topics including the chemical composition of textile waste water, the chemistry of the dye molecules, the selection of a treatment technique, the benefits and drawbacks of the various treatment options, and the cost of operation are also addressed. Overall, this review offers a valuable resource for researchers and industry professionals working in the textile industry, pointing towards a more sustainable and environmentally responsible future.

Evaluation of Photocatalytic, Antioxidant, and Antibacterial Efficacy of Almond Oil Capped Zinc Oxide Nanoparticles

In this study, ZnO nanoparticles (NPs) were synthesized in the presence of almond oil at various molar ratios of zinc acetate and sodium hydroxide, including 0.5:1, 0.75:1, 1:1, 1.25:1, and 1.5:1, to obtain pH values of 11, 10, 9, 8, and 7, respectively. The XRD results revealed that ZnO NPs exhibit a hexagonal structure, with high crystallinity. SEM results showed that dense and large sized ZnO NPs were formed at pH 11, and relatively small (~30-40 nm) NPs were obtained at pH 9. The size distribution can be explained in terms of the presence of OH- ions at different pH levels. However, the larger size of the NPs at pH 7 compared to those at pH 8-11 were due to the coalescence of NPs suitable for antioxidant/antibacterial activities. ZnO NPs demonstrated a high degradation efficiency (~93%) in 90 min, with a high rate constant for Methyl Orange (MO), which is better than the previously reported rate. The larger sized almond oil capped ZnO NPs also showed excellent radical scavenging activity (94%) and are proven to be good carriers to resist Escherichia coli (E. coli) bacteria.

Green Nanomaterials for Smart Textiles Dedicated to Environmental and Biomedical Applications

Smart textiles recently reaped significant attention owing to their potential applications in various fields, such as environmental and biomedical monitoring. Integrating green nanomaterials into smart textiles can enhance their functionality and sustainability. This review will outline recent advancements in smart textiles incorporating green nanomaterials for environmental and biomedical applications. The article highlights green nanomaterials' synthesis, characterization, and applications in smart textile development. We discuss the challenges and limitations of using green nanomaterials in smart textiles and future perspectives for developing environmentally friendly and biocompatible smart textiles.

Radiation synthesis and photocatalytic performance of floated graphene oxide decorated ZnO/ alginate-based beads for methylene blue degradation under visible light irradiation

Organic dye contamination, emanating from pharmaceutical, paper, and textile industries into water resources, severely threatens marine and human life even at low concentrations. Photocatalysis is one of the most important remediation techniques that decolorize water by employing the power of light. In this work, the development of floated beads of Sodium Alginate/hydroxyethyl methacrylate (Alg-g-HEMA) encompass graphene oxide (GO) decorated Zinc oxide (ZnO) utilizing ionizing radiation was designed to function as a photocatalyst when exposed to visible light. Floatability was induced using calcium carbonate. GO was sonochemically decorated with ZnO nanoparticles and the yield was characterized using XRD, FTIR, TEM, SEM, and EDX techniques. Optical characteristics of the developed nanostructure were performed using UV-Vis spectrophotometry. The photocatalytic activity of the floated (Alg-g-HEMA)-ZnO@GO beads was assessed for the photo decolorization of methylene blue dye (MB) under visible light. The upshot of operational factors such as photocatalyst dose, pH, initial dye concentration, and irradiation time on the decolorization of MB was examined. It was observed that 1 g of the developed (Alg-g-HEMA)-ZnO@GO photocatalyst was able to decolorize 1000 ml of 20 ppm of MB within 150 min at pH 9. In terms of kinetics, photo-decolorization follows Langmuir Hinshelwood pseudo-first order.

Silica sand-supported nano zinc oxide-graphene oxide composite induced rapid photocatalytic decolorization of azo dyes under sunlight and improved antimicrobial activity

Here, silica sand-supported heterojunction composite of nano zinc oxide (nZnO) and graphene oxide nanosheet (nZnO-GO@SS) was prepared, and its potential as an efficient photocatalyst for the degradation of methylene blue (MB) and Rhodamine-B (Rh-B) under sunlight was demonstrated. Transmission electron microscopy confirmed the uniform distribution of spherically shaped nZnO of average size of approximately 8 nm over graphene oxide nanosheet (GO) in the composites. Photodegradation yields of 95.3% and 97.5% for 100 ppm of MB and Rh-B dye within 150 and 220 min, respectively, were achieved under sunlight by the prepared nanocatalyst (nZnO-GO), while sand microparticle-supported nanocatalyst (nZnO-GO@SS) demonstrated faster degradation of MB and Rh-B, i.e., within 120 and 160 min, respectively. Furthermore, when the recyclability of the photocatalyst was studied, the nZnO-GO exhibited more than 80% degradation efficiency after five cycles for both the dyes and nZnO-GO@SS demonstrated 10% higher (~90%) removal capability after five cycles of reuse. Furthermore, the antibacterial assay showed complete inactivation of Escherichia coli and Staphylococcus aureus bacterial strain by nZnO-GO@SS. Hence, our proposed strategy for the removal of toxic dyes from the aquatic environment under sunlight proved that sand microparticle-supported nanocatalyst (nZnO-GO@SS) might be a superior, cost-effective, and suitable photocatalytic system for industrial applications toward toxic dye removal and decontamination from industrial wastewater.

Design and modeling of diazinon degradation in hydrous matrix by Ni-doped ZnO nanorods under ultrasonic irradiation: process optimization using RSM (CCD), kinetic study, reaction pathway, mineralization, and toxicity assessment

In first, the Ni-doped ZnO nanorods used as an appeal sonocatalyst was synthesized through co-precipitation method. Afterwards, the crystalline structure, functional groups, surface morphology, and elemental composition were characterized by a set of analysis. Removal of diazinon ((DZ) as a renowned pesticide) was investigated using sonocatalytic performance of US/Ni-doped ZnO system. In this empirical study, response surface methodology (RSM) based central composite design (CCD) was applied for optimization of operational factors. Under the optimum conditions such as initial pH = 5, initial DZ concentration = 15 mg L^-1, sonocatalyst dosage = 1 g L^-1, and in the presence of organic compounds (oxalic acid, humic acid, and folic acid) = 3 mg L^-1, the sonocatalytic degradation of DZ after 15 min was 82.29%. The F-value (6.64) and P-value (< 0.0001) for DZ degradation in the quadratic model imply the proposed model was significant. A-factor (pH) considers as a prominent factor owing to having the highest F-value. In addition, the sonocatalytic data in this study exhibited valid fitting for the first order kinetic model (R² > 0.98). After six consecutive cycles, the Ni-doped ZnO nanorods could be recyclable for sonocatalytic degradation of DZ. The five main compounds produced during the US/Ni-doped ZnO embracing 2-isopropyl-6-methyl-4-pyrimidinol (IMP), diethyl phosphonate, diazoxon, hydroxyldiazinon, and diazinon methyl ketone are formed in the path of DZ degradation. OFAT style also revealed 99.99% of DZ degradation with 73.26% of mineralization rate in optimum status. The Ni-doped ZnO presented agreeable sonocatalytic facility in the refinement of real water and wastewater matrix. Finally, the results of toxicity evaluation (Daphnia magna) in the sonocatalytic degradation of DZ (by US/Ni-doped ZnO system) showed that the toxicity of the DZ solution lessened under US waves (LC₅₀ and TU 48 h equal to 36.472 and 2.741 volume percent, respectively).

Ceria nanoparticles anchored on graphitic oxide sheets (CeO2-GOS) as an efficient catalyst for degradation of dyes and textile effluents

Herein, we report a Ceria-graphitic oxide sheets (CeO₂-GOS) nanocomposites photo catalyst synthesized by simple and green methods for the degradation of textile effluents and dyes. In the first step, green treated CeO₂ NPs were synthesized through a simple organic reduction method. Further, green synthesized CeO₂ NPs were anchored with GOS to produce CeO₂-GOS nanocomposites by a sol-gel method. The phase morphology and structure of CeO₂-GOS nanocomposites was systematically characterized through X-ray diffraction, Raman spectroscopy, zeta potential, Fourier transform infrared spectroscopy (FT-IR), High-Resolution Transmission Electron Microscope (HR-TEM), and X-ray photoelectron spectroscopy (XPS) analysis. Under visible light irradiation, the CeO₂-GOS nanocomposites photo catalyst exhibited 83%, 78%, and 70% degradation efficiencies for rhodamine B, methylene blue, and textile effluent, respectively. Due to the synergistic impact of GO, it act as an elastic conductive channel permitting improved charge transport, the fabricated CeO₂-GOS nanocomposites showed a significant retort to photo catalysis of rhodamine B, methylene blue, and textile effluent. CeO₂-GOS nanocomposites may yield unique insight into the synthesis of green nanocomposites and their application in environmental remediation due to their better photo catalytic activity.

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants.