Eliminating pesticide quinalphos from surface waters using synthesized GO-ZnO nanoflowers: Characterization, degradation pathways and kinetic study

Copper Oxide Anchored Carbon Nanofibers: A Versatile Platform for Multiplex Detection of Antibiotics, Heavy Metals and Pesticides

Electrochemical sensors offer promising prospects for real-time pollutant monitoring. In this study, copper oxide-dispersed graphitic carbon nanofibers (CuO-CNFs) grown via chemical vapour deposition were employed as a robust platform for detecting a variety of environmental pollutants. This array-based sensor adeptly identifies three different classes of analytes, i. e., antibiotics (chloramphenicol (CP) and tylosin tartrate (TT)), heavy metals (cadmium (Cd) and lead (Pb)), and pesticides (quinalphos (QP) and imidacloprid (IP)). Electron collection is facilitated by a glassy carbon electrode, while various physico-electrochemical methods delve into the properties of CuO-CNFs. The CuO-CNF-modified GCE array rapidly discerns (<15 sec) a broad linear range: 1-20 ppm for CP, 1-13.33 ppm for TT, 0.66-11.66 ppm for Cd, 20-33.33 ppm for Pb, 1.6-11.6 ppm for QP, and 5-25 ppm for IP, boasting quantification limits of 1.0, 1.0, 0.66, 20.0, 1.6, and 5.0 ppm for CP, TT, Cd, Pb, QP, and IP, respectively. Notably, this sensor achieves simultaneous identification of mixed analytes, including CP and TT, Cd and Pb, and QP and IP, within real tap water. Furthermore, the electrochemical sensor exhibits robustness; heightened sensitivity, selectivity, and stability; a swift response; and impressive reproducibility in detecting CP, TT, Cd, Pb, QP, and IP within aqueous samples. Consequently, this array-based electrochemical sensor has emerged as a rapid and simultaneous detection tool for diverse pollutant residues in surface and groundwater samples.

Efficient removal of cationic dye using ZIF-8 based sodium alginate composite beads: Performance evaluation in batch and column systems

The environmental and health risks associated with dye contamination in water sources are alarming. Recently, researchers have been focusing on developing an innovative and susceptible solution using composite beads that effectively combat this issue. In this paper, beads were synthesized using a sodium alginate (SA) and zeolitic imidazolate framework-8 (ZIF-8) through a simple dipping process. Several characterization tests were performed including XRD, FTIR, BET, TGA, and SEM-EDX. The SEM images confirmed that SA effectively coated the cubical structure of the ZIF-8, ensuring optimal performance. The efficiency of the resulting SA@ZIF-8 composite beads was tested on both synthetic malachite green dye and real industrial wastewater samples using batch and fixed bed column reactors. The findings revealed that maximum adsorption of 95.5% was achieved at pH 6 in 120 min of reaction time. FTIR and SEM analysis also confirmed the adsorption of MG dye onto the beads. The Freundlich isotherm model (R2 > 0.99) has a better fit than the Langmuir (R2 > 0.96) for describing the adsorption process. The PSO model predicted the kinetics of the system, whereas the intraparticle diffusion study supported the system's mechanistic analysis. Furthermore, the study also investigated the efficacy of the beads in treating real wastewater effluent samples collected from the dye industry. Overall, using sodium alginate-coated ZIF-8 beads was found to have many advantages over powdered ZIF-8, including higher selectivity, stability, reusability, and practicality, making them a promising alternative for adsorption applications. Therefore, these composite beads have the potential for the removal of the dye from wastewater, which could be widely applied in various industries.

New roles for Bacillus thuringiensis in the removal of environmental pollutants

For a long time, the well-known Gram-positive bacterium Bacillus thuringiensis (Bt) has been extensively studied and developed as a biological insecticide for Lepidoptera and Coleoptera pests due to its ability to secrete a large number of specific insecticidal proteins. In recent years, studies have found that Bt strains can also potentially biodegrade residual pollutants in the environment. Many researchers have isolated Bt strains from multiple sites polluted by exogenous compounds and characterized and identified their xenobiotic-degrading potential. Furthermore, its pathway for degradation was also investigated at molecular level, and a number of major genes/enzymes responsible for degradation have been explored. At present, a variety of xenobiotics involved in degradation in Bt have been reported, including inorganic pollutants (used in the field of heavy metal biosorption and recovery and precious metal recovery and regeneration), pesticides (chlorpyrifos, cypermethrin, 2,2-dichloropropionic acid, etc.), organic tin, petroleum and polycyclic aromatic hydrocarbons, reactive dyes (congo red, methyl orange, methyl blue, etc.), and ibuprofen, among others. In this paper, the biodegrading ability of Bt is reviewed according to the categories of related pollutants, so as to emphasize that Bt is a powerful agent for removing environmental pollutants.

Water remediation using titanium and zinc oxide nanomaterials through disinfection and photo catalysis process: A review

Various pesticides and organic compounds generated as a result of rapid industrialization and pharmaceutical companies pose a major threat to the environment. Novel photocatalysts based on zinc oxide and titanium oxide exhibit great potential towards absorption of these organic pollutants from wastewater. The photocatalysts possess various extraordinary properties like photocatalytic degradation potential, non-toxic and high stability. However, several limitations are also associated with the applications of these photocatalysts like poor affinity, particle agglomeration, high band gap and recovery issues. Hence, optimization is required to enhance their efficiency and at the same time make them cost effective and sustainable. The review covers the mechanism for water treatment, limitations and development of different modification strategies that improve the removal efficiency of titanium and zinc oxide based photocatalysts. Thus, further research in the field of photocatalysts can be encouraged for carrying out water remediation.

Photocatalytic degradation of dissolved organic matter in landfill leachate by heterostructural ZnO-rGO composite catalysts

The dissolved organic matter (DOM) in landfill pollutes not only the landfill and surroundings, but also the environment far away from the landfill by infiltrating into the soil and/or flowing on the ground surface. Developing an efficient photocatalyst to degrade DOM is an interesting topic. Herein, the catalysts composed of ZnO and reduced graphene oxide (ZnO-rGO) with different morphologies were fabricated with a two-step hydrothermal method. The phase composite and microstructure were analyzed, and the degradation efficiency of the DOM under ultraviolet light was investigated. Three kinds of ZnO-rGO composite catalysts with different morphologies were successfully synthesized, and rGO was coated on the ZnO surface to form heterostructural composite catalysts. The catalyst powders have similar Raman and FT-IR spectra, but have different specific surface areas and band gaps. The degradation efficiency of DOM by ZnO-rGO composites is higher than that of pure ZnO powder. Compared to pure ZnO, ZnO-rGO composite catalysts contain more oxygen vacancies and a narrower band gap, and the heterostructure is beneficial for accelerating electron separation, inhibiting electron recombination.

Self-propelled nanojets an interfacial Schottky junctions modulated oxygen vacancies enriched for enhanced photo-Fenton degradation of organic contaminant: Improving H2O2 generation, Fe3+/Fe2+ cycle and enhancing plant metabolism

The study reports an innovative approach on sunlit driven heterostructure photocatalytic generation of H₂O₂ and removal of cefixime. In the present work, we have fabricated Mn/Mg doped CoFe₂O₄ modified CaCr₂O₄ decorated by Ag₃PO₄ quantum dots (Ag₃PO₄ QDs), a p-n-p nano heterojunction. The study promotes the photocatalytic production of H₂O₂ and self-Fenton photocatalytic degradation of cefixime. Egg white-assisted synthesis of Mn-doped CoFe₂O₄ causes the lattice oxygen defect, which enhances the photocatalytic activity. Lattice oxygen defect enable the adsorption of O₂, which enable the conversion of •O² in the valence band of CoFe₂O₄ for the endogenous production of H₂O₂. The higher in the surface area enhance the photocatalytic activity under visible light irradiation. Mn-CoFe₂O₄-CaCr₂O₄-Ag₃PO₄ QDs enables the complete photocatalytic degradation of cefixime (99.9%) and the complete removal was determined by total organic carbon (TOC) removal and it was around 99.4%. Meanwhile the photocatalytic degradation pathway of cefixime was determined by LC-MS/MS. Reusability of the nano heterojunction was determined by six cycle test, and the reusability of the nano heterojunction was 99.8%. Further, the toxicity of the nanomaterial was studied in maize plant and the results shows that the nanoheterojunction enhances the maize growth. The study systematically reveals the robust activity of nano heterojunction for sustainable water treatment.

Challenges and effectiveness of nanotechnology-based photocatalysis for pesticides-contaminated water: A review

Pesticides have been frequently used in agricultural fields. Due to the expeditious utilization of pesticides, their excessive usage has negative impacts on the natural environment and human health. This review discusses the successful implications of nanotechnology-based photocatalysis for the removal of environmental pesticide contaminants. Notably, various nanomaterials, including TiO₂, ZnO, Fe₂O₃, nanoscale zero-valent iron, nanocomposite-based materials, have been proposed and have played a progressively essential role in wastewater treatment. In addition, a detailed review of the crucial reaction condition factors, including water matrix, pH, light source, temperature, flow rate (retention time), initial concentration of pesticides, a dosage of photocatalyst, and radical scavengers, is also highlighted. Additionally, the degradation pathway of pesticide mineralization is also elucidated. Finally, the challenges of technologies and the future of nanotechnology-based photocatalysis toward the photo-degradation of pesticides are thoroughly discussed. It is expected that those innovative extraordinary photocatalysts will significantly enhance the performance of pesticides degradation in the coming years.

The Oxygen Vacancy Defect of ZnO/NiO Nanomaterials Improves Photocatalytic Performance and Ammonia Sensing Performance

In this paper, ZnO/NiO composites rich in oxygen vacancies are prepared by the solvothermal method and reduction method. In the test, through the use of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR), we effectively prove the existence of phase, morphology and oxygen vacancies in the material. Through the photocatalysis test and gas sensitivity test, it is found that 10% Ni doped OZN-10 has the best photocatalytic activity and gas sensitivity characteristics. The degradation rate of methylene blue (MB) was 98%. The gas sensitivity test shows that OZN-10 has good selectivity, good response performance (3000 ppm, 27,887%) and excellent response recovery time (response time: 50 s, recovery time: 5–7 s) for saturated NH₃ gas at standard atmospheric pressure (101.325 KPa) and room temperature (25 °C). The synergistic effect of oxygen vacancy as the center of a trap and p–n heterojunction forming an electric potential field at the interface is explained, and the mechanism of improving photocatalysis and gas sensitivity is analyzed. This work will provide an innovative vision for dual-performance oxygen vacancy modification of heterojunctions through photocatalysis.