Degradation of pesticides chlorpyrifos, cypermethrin and chlorothalonil in aqueous solution by TiO2 photocatalysis

Mechanisms in the photocatalytic breakdown of persistent pharmaceutical and pesticide molecules over TiO2-based photocatalysts: A review

Titanium dioxide (TiO2) based photocatalysts have been widely used as a photocatalyst for the degradation of various persistent organic compounds in water and air. The degradation mechanism involves the generation of highly reactive oxygen species, such as hydroxyl radicals, which react with organic compounds to break down their chemical bonds and ultimately mineralize them into harmless products. In the case of pharmaceutical and pesticide molecules, TiO2and modified TiO2photocatalysis effectively degrade a wide range of compounds, including antibiotics, pesticides, and herbicides. The main downside is the production of dangerous intermediate products, which are not frequently addressed in the literature that is currently available. The degradation rate of these compounds by TiO2photocatalysis depends on factors such as the chemical structure of the compounds, the concentration of the TiO2catalyst, the intensity, the light source, and the presence of other organic or inorganic species in the solution. The comprehension of the degradation mechanism is explored to gain insights into the intermediates. Additionally, the utilization of response surface methodology is addressed, offering a potential avenue for enhancing the scalability of the reactors. Overall, TiO2photocatalysis is a promising technology for the treatment of pharmaceutical and agrochemical wastewater, but further research is needed to optimize the process conditions and to understand the fate and toxicity of the degradation products.

Integrated Electrochemical Oxidation and Biodegradation for Remediation of a Neonicotinoid Insecticide Pollutant

A novel integrated electrochemical oxidation (EO) and bacterial degradation (BD) technique was employed for the remediation of the chloropyridinyl and chlorothiazolyl classes of neonicotinoid (NEO) insecticides in the environment. Imidacloprid (IM), clothianidin (CL), acetamiprid (AC), and thiamethoxam (TH) were chosen as the target NEOs. Pseudomonas oleovorans SA2, identified through 16S rRNA gene analysis, exhibited the potential for BD. In EO, for the selected NEOs, the total percentage of chemical oxygen demand (COD) was noted in a range of 58-69%, respectively. Subsequently, in the biodegradation of EO-treated NEOs (BEO) phase, a higher percentage (80%) of total organic carbon removal was achieved. The optimum concentration of NEOs was found to be 200 ppm (62%) for EO, while for BEO, the COD efficiency was increased up to 79%. Fourier-transform infrared spectroscopy confirms that the heterocyclic group and aromatic ring were degraded in the EO and further utilized by SA2. Gas chromatography-mass spectroscopy indicated up to 96% degradation of IM and other NEOs in BD (BEO) compared to that of EO (73%). New intermediate molecules such as silanediamine, 1,1-dimethyl-n,n'-diphenyl produced during the EO process served as carbon sources for bacterial growth and further mineralized. As a result, BEO enhanced the removal of NEOs with a higher efficiency of COD and a lower consumption of energy. The removal efficiency of the NEOs by the integrated approach was achieved in the order of AC > CL > IM > TH. This synergistic EO and BD approach holds promise for the efficient detoxification of NEOs from polluted environments.

Studies on photocatalytic mineralization of organic pesticides by bimetallic Cu-Zn nanoparticles derived from Zingiber officinale Roscoe (ginger) using green chemistry approach

Compared to monometallic nanoparticles, bimetallic nanoparticle synthesis and characterization have attracted more attention due to their superior environmental protection properties. In this study, we discuss the preparation and characterization of Cu-Zn bimetallic nanoparticles using Zinger extract, as well as their potential role in photocatalytic degradation of carbendazim, chlorpyrifos, monocrotophos, and cypermethrin. Surface properties were assessed with SEM and TEM, while UV-VIS, XRD, FTIR, and fluorescence spectroscopy were used to characterize the materials. It was observed that higher pH conditions were more conducive to the development of stable Cu-Zn BMNPs with diameters ranging from 60 to 100 nm. UV-VIS spectroscopy showed that the Cu-Zn bimetallic nanoparticles photodegraded 53-95% of the pesticides, monocrotophos, chlorpyrifos, and carbendazim during the 24-72-h incubation period. A number of pesticides may be photocatalytically degraded by primary reactive radicals produced by nanoparticles. We propose that the use of bimetallic nanoparticles could be one alternative strategy for pesticide mineralization.

Surface-Functionalized Magnetic Silica-Malachite Tricomposite (Fe-M-Si tricomposite): A Promising Adsorbent for the Removal of Cypermethrin

This study assessed the efficacy of adsorption for eliminating the agricultural pesticide cypermethrin (CP) from wastewater using various adsorbents: silica, malachite, and magnetite. Magnetic nanocomposites (NCs) (with varying amounts of Fe3O4 0.1, 0.25, 0.5, 1.0, and 1.5 wt/wt %) were synthesized, including Fe3O4 nanoparticles (NPs), bicomposites, and tricomposites, calcined at 300 and 500 °C, and then tested for CP removal. The study was conducted in two phases, with the objective of initially assessing how effectively each individual NP performed and then evaluating how effectively the NCs performed when used for the adsorption of CP. Notably, the Fe3O4-malachite combination exhibited superior CP removal, with the 0.25-Fe-M NC achieving the highest adsorption at 635.4 mg/g. This success was attributed to the large surface area, magnetic properties of Fe3O4, and adsorption capabilities of malachite. The Brunauer-Emmett-Teller (BET) isotherm analysis indicated that the NCs had potential applications in adsorption and separation processes. The scanning electron microscopy and transmission electron microscopy revealed the spherical, irregular shaped morphology of the synthesized NPs and NCs. However, the X-ray diffraction (XRD) pattern of surface functionalized materials such as surface functionalized malachite [Cu2CO3(OH)2] with Fe3O4 and SiO2 may be complicated by the specific functionalization method used and the relative amounts and crystallographic orientations of each component. Therefore, careful interpretation and analysis of the XRD pattern, along with other techniques, are necessary for accurate identification and characterization of the functionalized material. The originality of this study lies in its comprehensive investigation of several adsorbents and NCs for CP removal at neutral pH. The innovation stems from the synergistic action of Fe3O4 and malachite, which results in improved CP removal due to their combined surface properties and magnetic characteristics. The application of magnetic NCs in adsorption and separation, as validated by BET isotherm analysis, highlights the potential breakthrough in addressing pesticide contamination.

A Review on Nanomaterial as Photocatalysts for Degradation of Organic Pollutants

Eliminating hazardous organic contaminants from water is a major concern today. Nanomaterials with their textural features, large surface area, electrical conductivity, and magnetic properties make them efficient for the removal and photocatalytic degradation of organic pollutants. The reaction mechanisms of the photocatalytic oxidation of common organic pollutants were critically examined. A detailed review of articles published on photocatalytic degradation of hydrocarbons, pesticides, and dyes was presented therein. This review seeks to bridge information gaps on the reported nanomaterial as photocatalysts for the degradation of organic pollutants under sub-headings, nanomaterials, organic pollutants, degradation of organic pollutants, and mechanisms of photocatalytic activities.

The Catalytic Role of Superparamagnetic Iron Oxide Nanoparticles as a Support Material for TiO2 and ZnO on Chlorpyrifos Photodegradation in an Aqueous Solution

Chlorpyrifos (CP) is a globally used pesticide with acute toxicity. This work studied the photocatalytic degradation of CP using TiO2, ZnO nanoparticles, and nanocomposites of TiO2 and ZnO supported on SPIONs (SPION@SiO2@TiO2 and SPION@SiO2@ZnO). The nanocomposites were synthesized by multi-step incipient wetness impregnation. The effects of the initial pH, catalyst type, and dose were evaluated. The nanocomposites of SPION@SiO2@TiO2 and SPION@SiO2@ZnO showed higher CP photodegradation levels than free nanoparticles, reaching 95.6% and 82.3%, respectively, at pH 7. The findings indicate that iron oxide, as a support material for TiO2 and ZnO, extended absorption edges and delayed the electron-hole recombination of the nanocomposites, improving their photocatalytic efficiency. At the same time, these nanocomposites, especially SPION@SiO2@TiO2, showed efficient degradation of 3,5,6-trichloropyridinol (TCP), one of the final metabolites of CP. The stability and reuse of this nanocomposite were also evaluated, with 74.6% efficiency found after six cycles. Therefore, this nanomaterial represents an eco-friendly, reusable, and effective alternative for the degradation of chlorpyrifos in wastewater treatment.

Photocatalytic degradation of chlorpyrifos using Ag nanoparticles-doped g-C3N5 decorated with dendritic CdS

In this work, g-C3N5/CdS dendrite/AgNPs nanocomposite was synthesized using a mixed method consisting of hydrothermal, ultrasonic and chemistry reduction with sodium borohydride. The characterization of the as-prepared nanocomposite was done using infrared spectroscopy, X-ray, scanning electron microscopy, transmission electron microscopy, BET, and DRS methods was performed. The DRS results showed that the g-C3N5/CdS dendrite/AgNPs nanocomposite nanocomposite has a band gap of 1.08 eV. This band gap indicates the good capability of this nanocomposite as a photocatalyst. Accordingly, the photocatalytic degradation of chlorpyrifos (CPS) in was performed in an aqueous solution of the synthesized nanocomposite. The results showed that almost 95.3% of this poison, a concentration of 50 mg L-1 was degraded in the presence of 0.05 g L-1 of nanocomposite at pH = 5 in a 60 min. Hydroxide radicals and holes play a significant role in the photocatalytic process. The reusability of the nanocomposite with excellent performance in the degradation of photocatalytic toxins caused by the reduction in the electron-hole recombination and the high surface area of the nanocomposite are among the unique features of this work.

Photocatalytic performance of SiO2@TiO2 spheres in selective conversion of oxidation of benzyl alcohol to benzaldehyde and reduction of nitrobenzene to aniline

Selective photocatalytic oxidation of benzyl alcohol to benzaldehyde and reduction of nitrobenzene to aniline reactions are investigated by using SiO2@TiO2 spheres produced in a simple route using chitosan as a template. The spheres are predominantly macroporous and, the XRD points out an amorphous crystallographic profile suggesting the uniform distribution of TiO2. Under low-power lighting for 4 hours, the conversions achieved was of the order of 49% and 99% for benzyl alcohol and nitrobenzene, respectively, with selectivity to benzaldehyde and aniline of 99% in both reactions. The study also follows the effects of the solvent and the presence of O2.

Meta-analysis of metal nanoparticles degrading pesticides: what parameters are relevant?

The rise in the global population demands an increasing food supply and methods to boost agricultural production. Pesticides are necessary for agricultural production models, avoiding losses of close to 40%. Nevertheless, the extensive use of pesticides can cause their accumulation in the environment, causing problems for human health, biota, and ecosystems. Thus, new technologies have emerged to remove these wastes efficiently. In recent years, metal and metal oxide nanoparticles (MNPs) have been reported as promising catalysts to degrade pesticides; however, a systematic understanding of their effect on pesticide degradation is still required. Therefore, this study focused on a meta-analysis of articles available in Elsevier's Scopus and Thomas Reuters Web of Science, found by searching for "nanoparticle pesticide" and "pesticide contamination." After passing different filters, the meta-analysis was performed with 408 observations from 94 reviews, which comprise insecticides, herbicides, and fungicides, including organophosphates, organochlorines, carbamates, triazines, and neonicotinoids. Herein, 14 different MNPs (Ag, Ni, Pd, Co₃O₄, BiOBr, Au, ZnO, Fe, TiO₂, Cu, WO₃, ZnS, SnO₂, and Fe⁰), improved pesticide degradation, with the highest degradation rates achieved by Ag (85%) and Ni (82.5%). Additionally, the impact of the MNP functionalization, size, and concentration on pesticide degradation was quantified and compared. In general, the degradation rate increased when the MNPs were functionalized (~ 70%) compared to naked (~ 49%). Also, the particle size significantly affected the degradation of pesticides. To our knowledge, this study is the first meta-analysis performed about the impact of MNPs on pesticide degradation, providing an essential scientific basis for future studies.

Effects of plant morphology, vitamin C, and other co-present pesticides on the deposition, dissipation, and metabolism of chlorothalonil in pakchoi

Pesticide residues have been a focus of attention of food safety. Different varietal pakchoi plants grown in open fields were studied to understand effects of morphology, leaf wax content, and vitamin C on the deposition, dissipation, and metabolism of chlorothalonil. The loose pakchoi plants and flat leaves were conducive to pesticide deposition, but not plants with erect leaves. Chlorothalonil on nine varieties of pakchoi dissipated in the first-order kinetic with T1/2 s of 1.4 ~ 2.0 days. Vitamin C in pakchoi could promote the dissipation of chlorothalonil. Carbendazim could significantly promote the dissipation of chlorothalonil on pakchoi. Interestingly, four metabolites of chlorothalonil were identified in the pakchoi and the metabolic pathway was predicted by DFT calculations. The risk assessment showed that pakchoi were safe for consumption after 10 days of application of the recommended dose. This work provides important information for the understanding of deposition, dissipation, and metabolism of chlorothalonil in pakchoi.

Visible-Light-Driven Photocatalytic Degradation of Tetracycline Using Heterostructured Cu2O-TiO2 Nanotubes, Kinetics, and Toxicity Evaluation of Degraded Products on Cell Lines

This study first reports on the tetracycline photodegradation with the synthesized heterostructured titanium oxide nanotubes coupled with cuprous oxide photocatalyst. The large surface area and more active sites on TiO₂ nanotubes with a reduced band gap (coupling of Cu₂O) provide faster photodegradation of tetracycline under visible light conditions. Cytotoxicity experiments performed on the RAW 264.7 (mouse macrophage) and THP-1 (human monocytes) cell lines of tetracycline and the photodegraded products of tetracycline as well as quenching experiments were also performed. The effects of different parameters like pH, photocatalyst loading concentration, cuprous oxide concentration, and tetracycline load on the photodegradation rate were investigated. With an enhanced surface area of nanotubes and a reduced band gap of 2.58 eV, 1.5 g/L concentration of 10% C-TAC showed the highest efficiency of visible-light-driven photodegradation (∼100% photodegradation rate in 60 min) of tetracycline at pH 5, 7, and 9. The photodegradation efficiency is not depleted up to five consecutive batch cycles. Quenching experiments confirmed that superoxide radicals and hydroxyl radicals are the most involved reactive species in the photodegradation of tetracycline, while valance band electrons are the least involved reactive species. The cytotoxicity percentage of tetracycline and its degraded products on RAW 264.7 (-0.932) as well as THP-1 (-0.931) showed a negative correlation with the degradation percentage with a p-value of 0.01. The toxicity-free effluent of photodegradation suggests the application of the synthesized photocatalyst in wastewater treatment.

Photocatalytic degradation of cefixime using visible light-driven Z-scheme ZnO nanorod/Zn2TiO4/GO heterostructure

ZnO nanorod along with a Zn₂TiO₄/GO heterostructure with enhanced charge transfer capability was synthesized by a facile sol-gel method. FT-IR, XRD, XPS, TEM, SEM, EDX, UV-Vis DRS, photocurrent response and PL analyses were applied to characterize the as-prepared photocatalysts. To investigate the photocatalytic activity of the composite, Cefixime (CEF) removal under visible light was evaluated. The ZnO nanorod/Zn₂TiO₄/GO, including 65 wt% ZnO and 3 wt% graphene oxide, showed the highest CEF degradation and was selected as the optimal ternary composite. Reduction of electron-hole pair recombination rate, successful interfacial charge transfers, and more visible light reception in the Z-scheme system were the important reasons for improving the photocatalytic properties of ZnO nanorod/Zn₂TiO₄/GO. Effective operating parameters in the CEF photocatalytic removal process were optimized employing the response surface method and were as follows: photocatalyst dosage = 0.88 g/L, pH = 5, radiation time = 115 min, and CEF concentration = 10 ppm. The photocatalytic degradation% of CEF and total organic carbon (TOC) removal% under the optimal conditions were 71.4 and 57.5%, respectively, for the three-component composite indicating the production of intermediate species during the process. This photocatalytic reaction confirmed the first-order kinetic and using the ZnO nanorod/Zn₂TiO₄/GO composite was able to improve the reaction rate by about 2.7 and 6.2 times more than ZnO nanorod/Zn₂TiO₄ and ZnO, respectively. The effects of radiation intensity and temperature were investigated and 175 W/m² and 35 °C were obtained as optimum values. Eventually, according to the trapping test, h⁺, superoxide radical, and hydroxyl radical are the most effective active species in this photocatalytic reaction, respectively.

A sustainable composite of rice-paper/BaMoO4 nanoparticles for the photocatalytic elimination of the recalcitrant 2,6-dichlorobenzamide (BAM) pesticide in drinking water and its mechanisms of degradation

This research reports the use of biodegradable and flexible composites for the removal of the 2,6-dichlorobenzamide (BAM) pesticide from drinking water. Rice paper (a biodegradable substrate) and Ag/BaMoO4 (MOBA) nanoparticles were employed to fabricate these composites. The SEM images showed that the MOBA nanoparticles with sizes of 300-800 nm decorated the surface of the biodegradable substrate and formed porous agglomerates, which have sizes of 1-3 μm. The MOBA powders were dispersed in drinking water polluted with BAM and were exposed to 4 h of UV-VIS irradiation, producing a maximum degradation of 82% for the BAM. Moreover, the flexible and biodegradable rice/MOBA composite produced a maximum removal percentage of 95% for the BAM. Also, we studied the effect of pH of the initial solution utilizing both powders and composites. From here, we found that a pH of 10 leads to a complete degradation of BAM after 4h, while a pH of 3 degraded only 37-47% of BAM for the same reaction time. According to the scavenger experiments, the •OH radical and the h+ were the main oxidizing agents for the BAM. Overall, the biodegradable photocatalytic composites are a reliable and a low-cost alternative to eliminate pesticides from the drinking water and can find application in water purification processes.

Titanium dioxide based nanocomposites - Current trends and emerging strategies for the photocatalytic degradation of ruinous environmental pollutants

Many ruinous pollutants are omnipresent in the environment and among them; pesticides are xenobiotic and pose to be a bio-recalcitrance. Their detrimental ecological and environmental impacts attract attention of environmental excerpts and the surge of stringent regulations have endows the need of a technically feasible treatment. This critical review emphasizes about the occurrence, abundance and fate of structurally distinct pesticides in different environment. The practiced remedial strategies and in particular, the advanced oxidation processes (AOPs) those utilize the photo-catalytic properties of nano-composites for the degradation of pollutants are critically discussed. Photo-catalytic degradation utilizes many composite materials at nano-scale level, wherein synthesis of nano-composites with appropriate precursors and other adjoining functional moieties are of prime importance. Therefore, suitable starter materials along with the reaction conditions are prerequisite for effectively tailoring the nano-composites. The aforementioned aspects and their customized applications are critically discussed. The associated challenges, opportunities and process economics of degradation using photo-catalytic AOP techniques are highlighted and in addition, the review tries to explain how best the photo-degradation can be a stand-alone tool with a societal importance. Conclusively, the future prospects for undertaking new researches in photo-catalytic breakdown of pollutants that can be judiciously sustainable.

Advanced catalytic oxidation coupled to biological systems to treat pesticide-contaminated water: A review on technological trends and future challenges

This article had the one and only objective of consolidating the couplings of advanced oxidation processes and biological systems in the decontamination of wastewater with pesticide content reported in the Scopus and Web of Science databases, through a critical analysis of which have been the most used, what methodologies have been implemented to develop them, identifying the objectives of each work, determining the success of the research and where the main niches of knowledge are, which can lead to the generation of new scientific knowledge as well as future trends. A co-occurrence analysis was carried out through the VOSViewer software to determine the most associated key words with the treatment configurations described above. Fenton and Photo-Fenton processes, heterogeneous photocatalysis TiO₂/UV, electrocatalysis, ozonization and a particular case of hydrodynamic cavitation-ozone as main advanced oxidation processes, together with advanced biological processes such as sequential batch bioreactor (SBR), membrane bioreactor (MBR), mobile bed biofilm reactor (MBBR); biodegradability and toxicity tests with bacterial strains and surface wetlands, whose treatment philosophy is activated sludge. The main future trends are the reuse of treated wastewater, the analysis and control of costs towards the efficient use of resources and the primary study of the byproducts generated in advanced oxidation to improve the efficiencies in the coupling.

Selective, stepwise photodegradation of chlorothalonil, dichlobenil and dichloro- and trichloro-isophthalonitriles enhanced by cyanidin in water

Chlorothalonil, a widely used chloroisophthalonitrile fungicide, is highly toxic to aquatic organisms and amphibians. It is essential to understand the persistence and fate of chlorothalonil in aquatic environments. Cyanidin is one of the most common phytopolyphenolics in nature and is a strong antioxidant. This study was designed to understand fate of chlorothalonil and its analogs in surface water in the presence of cyanidin under sunlight and artificial lights. The photodegradation rates of chlorothalonil were increased by 9.6, 19, 26 and 9.1 fold, respectively, under solar, high-pressure mercury lamp (HPML), UV and Xenon lamp light irradiation, in comparison to the cyanidin-free control. Cyanidin also enhanced 2,5-dichloroisophthalonitrile and 2,4,5-trichloro isophthalonitrile (degradation products of chlorothalonil) for 20 and 4.7 fold under HPML irradiation compared to the absence of cyanidin. Chlorothalonil was transformed to 5-chloroisophthalonitrile quantitatively after stepwise dechlorination. The concentration profiles of chlorothalonil and its degradation products were well simulated in the cyanidin-triggered photoreductive dechlorination process, in which donation of hydrogen atom from cyanidin was also agreed by the density functional theory calculations. Cyanidin accelerated photolysis of dichlobenil for 4.3 fold as high as the cyanidin-free control under HPML irradiation. The results warrant an interest in further understanding photolysis of chloroarenes in natural waters and exploring the potential of using phytochemicals to abate chloroarenes-caused pollution.

Fabrication of zirconium-based metal-organic frameworks@tungsten trioxide (UiO-66-NH2@WO3) heterostructure on carbon cloth for efficient photocatalytic removal of tetracycline antibiotic under visible light

Designing recyclable photocatalysts with high activity and stability has drawn considerable attention in the fields of sewage treatment. Herein, a series of heterojunctions constructed by zirconium-based metal-organic frameworks (UiO-66-NH₂) and tungsten trioxide (WO₃) is immobilized on carbon cloth via a facile solvothermal method, resulting in highly recyclable photocatalysts. Multiple characterization techniques, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, verify the successful synthesis of UiO-66-NH₂ nanospheres on the surface of needlelike WO₃ modified carbon cloth. Results show that the optimal heterojunction photocatalyst exhibits excellent photocatalytic degradation efficiency for the removal of tetracycline (TC) from water, for which nearly 100% of TC is degraded within 60 min under visible light. Trapping experiments and electron spin resonance (ESR) spectra analyses demonstrate that the superoxide radicals O₂^- and photogenerated hole h⁺ play a dominant role in the degradation process. Excellent photocatalytic activity is dominantly attributed to the effective separation of photoinduced carriers in this type-Ⅱ heterostructure system. Moreover, the possible photocatalytic oxidation degradation pathway is confirmed by analyzing intermediates using liquid chromatography mass spectrometry (LC-MS). This study offers a highly efficient strategy to design recyclable heterojunction photocatalysts for the degradation of refractory antibiotics in sewage.

Ingeniously designed Silica nanostructures as an exceptional support: Opportunities, potential challenges and future prospects for viable degradation of pesticides

Despite significant advancements in modern agricultural practices, efficient handling of pesticides is a must as they are continuously defiling our terrestrial as well as aquatic life. During the last couple of decades, substantial efforts by various research groups have been devoted to find innovative solutions to remove pesticides from our environment in a greener way. In this regard, functionalized silica nanoparticles (NPs) have gained considerable attention of scientific community due to their notable properties such as amenable design, large surface area as well as fine-tunable and uniform pore structures which make them an ideal material for pesticides removal. The present review aims to proffer current scientific progress attained by silica-based nanostructures as an excellent material for effective removal of noxious agrochemicals. Further, a brief discussion on the synthetic strategies as well as intrinsic benefits associated with different morphologies of silica have also been highlighted in this article. It also summarizes the recent reports on silica assisted degradation of pesticides via enzymatic, chemical as well as advanced oxidation protocols. Additionally, it presents a critical analysis of different support materials for decontamination of our ecosystem. The review concludes with potential challenges, their possible solutions along with key knowledge gaps and future research directions for successful deployment of silica supported materials in degradation of pesticides at commercial scale.

Recent insights into SnO2-based engineered nanoparticles for sustainable H2 generation and remediation of pesticides

Due to the ongoing industrial revolution and global health pandemics, solar-driven water splitting and pesticide degradation are highly sought to cope with catastrophes such as depleting fossil reservoirs, global warming, and environmental degradation.

Recent advances in structural modifications of photo-catalysts for organic pollutants degradation - A comprehensive review

Over the last few years, industrial and anthropogenic activities have increased the presence of organic pollutants such as dyes, herbicides, pesticides, analgesics, and antibiotics in the water that adversely affect human health and the environment worldwide. Photocatalytic treatment is considered a promising, economical, effective, and sustainable process that utilizes light energy to degrade the pollutants in water. However, certain drawbacks like rapid recombination and low migration capability of photogenerated electrons and holes have restricted the use of photo-catalysts in industries. Hence, despite the abundance of lab-scale research, the technology is still not much commercialized in the mainstream. Several structural modifications in the photo-catalysts have been adopted to enhance the pollutant degradation performance to overcome the same. In this context, the present review article outlines the different advanced heterostructures synthesized to date for improved degradation of three major organic pollutants: antibiotics, dyes, and pesticides. Moreover, the article also emphasizes the degradation kinetics of photo-catalysts and the publication trend in the past decade along with the roadblocks preventing the transfer of technology from the laboratory to industry and new age photo-catalysts for the profitable implications in industrial sectors.

Photodegradation of Flucetosulfuron, a Sulfonylurea-Based Herbicide in the Aqueous Media Is Influenced by Ultraviolet Irradiation

Photodegradation (photolysis) causes the breakdown of organic pesticides molecules by direct or indirect solar radiation energy. Flucetosulfuron herbicide often encounters water bodies. For this reason, it is important to know the behavior of the compound under these stressed conditions. In this context, photodegradation of flucetosulfuron, a sulfonylurea-based herbicide, has been assessed in aqueous media in the presence of photocatalyst TiO₂ and photosensitizers (i.e., H₂O_2, humic acid, and KNO₃) under the influence of ultraviolet (UV) irradiation. The influence of different water systems was also assessed during the photodegradation study. The photodegradation followed the first-order reaction kinetics in each case. The metabolites after photolysis were isolated in pure form by column chromatographic method and characterized using the different spectral data (i.e., XRD, IR, NMR, UV-VIS, and mass spectrometry). The structures of these metabolites were identified based on the spectral data and the plausible photodegradation pathways of flucetosulfuron were suggested. Based on the findings, photocatalyst TiO₂ with the presence of ultraviolet irradiation was found effective for the photodegradation of toxic flucetosulfuron residues under aqueous conditions.

Recent developments in photocatalytic degradation of insecticides and pesticides

Widespread use of pesticides in agricultural and domestic sectors and their long half-life have led to their accumulation in the environment beyond permissible limits. Advanced chemical oxidation methods including photocatalytic degradation are being widely investigated for their mineralization. Photocatalytic degradation is the most promising method for degrading pesticides as well as other organic pollutants. Titanium dioxide with or without modification has been widely used as the photocatalyst. Some research groups have also tried other photocatalysts. This review presents a critical summary of the research results reported during the past two decades as well as the scope for future research in this area.

Removal of chlorpyrifos and its hydrolytic metabolite in microcosm-scale constructed wetlands under soda saline-alkaline condition: Mass balance and intensification strategies

Chlorpyrifos (CP) is a typical organophosphorus insecticide, which poses serious threats to the natural environment and human health. Strategies for the fast elimination of CP and its toxic hydrolytic metabolite 3,5,6-trichloro-2(1H)-pyridianol (TCP) in drainage water are urgently needed. The fate of CP and TCP in microcosm-scale subsurface batch constructed wetlands (SSBCWs) was quantified with different macrophyte species under soda saline-alkaline (SSA) condition and effective intensification strategies were developed. The macrophyte species Canna indica outperformed Phragmites australis and Typha orientalis for CP and TCP removal in SSBCWs. Mass balance calculation indicates the fate of CP in SSBCWs was residue in water (≤8%), alkaline hydrolysis (18.93-57.42%), microbial degradation (37.75-61.91%), substrate adsorption (~4-14%), and macrophyte uptake (≤3%). The addition of ferric-carbon (Fe-C) as a substrate amendment in SSBCWs increased the CP removal percentage by 35% and reduced the effluent TCP concentration by ~70% during Day 1-4 on average compared with the unintensified control. Fe-C addition simplified the microbial community diversity, while increasing the relative abundance of Proteobacteria which tolerates the microelectrolytic environment. A single application of liquid microbial agent improved CP removal percentage by 84% and decreased the effluent TCP concentration by two orders of magnitude during Day 1-4. The hydraulic retention time for thorough removal of TCP reduced from over 8 d to 4 d. Although only two dominant microbial genera (i.e., Sphingomonas and Pseudomonas) adapted to the environment with CP and SSA, they accelerated CP and TCP degradation via their own metabolism and co-metabolism with other indigenous microorganisms.

Secondary Metabolites from Artemisia Genus as Biopesticides and Innovative Nano-Based Application Strategies

The Artemisia genus includes a large number of species with worldwide distribution and diverse chemical composition. The secondary metabolites of Artemisia species have numerous applications in the health, cosmetics, and food sectors. Moreover, many compounds of this genus are known for their antimicrobial, insecticidal, parasiticidal, and phytotoxic properties, which recommend them as possible biological control agents against plant pests. This paper aims to evaluate the latest available information related to the pesticidal properties of Artemisia compounds and extracts and their potential use in crop protection. Another aspect discussed in this review is the use of nanotechnology as a valuable trend for obtaining pesticides. Nanoparticles, nanoemulsions, and nanocapsules represent a more efficient method of biopesticide delivery with increased stability and potency, reduced toxicity, and extended duration of action. Given the negative impact of synthetic pesticides on human health and on the environment, Artemisia-derived biopesticides and their nanoformulations emerge as promising ecofriendly alternatives to pest management.

[Recent developments of pesticide adsorbents based on cyclodextrins]

The invention and application of pesticides have greatly increased the yield of crops, greatly contributing to ensuring people's basic livelihoods and gradually improving their livelihoods to a well-off level. However, foods, water sources, and soil, containing high levels of pesticide residues, result in increasingly serious pollution. Pesticide residues usually have the characteristics of micro toxicity, difficult biodegradation, and bioaccumulation, and thus pose serious threat to living organisms and ecosystems. In recent years, pesticide pollution has earned worldwide focus. Thus, methods for the efficient detection of trace pesticides and reduction of the harm caused by pesticide pollution are urgently required. Researchers have used catalysis, electrochemistry, membrane separation, adsorption, and other methods to enrich pesticides from complex matrices. Among these, adsorbents have attracted much attention owing to their advantages of simple operation steps, rapid treatment process, and low amounts of organic solvents required. Research on adsorption materials has always been a very active field, and is also the key to the success of separation and enrichment of pesticides from complex matrices. Development of adsorbents with the advantages of simple synthesis, environment-friendliness, high stability, and strong reusability is of great significance. There has been some progress in the field of pesticide adsorption using supramolecular compounds. Cyclodextrin is a macrocyclic compound with a cavity after crown ether, which can form inclusion complexes via host guest interactions as the main body. Cyclodextrin can also be modified by etherification, esterification, oxidation, and other chemical reactions to improve its adsorption performance. Pesticides can be classified into organic and inorganic substances. One of the most widely used inorganic fungicides is the Bordeaux solution, whose main component is Cu2+. Organic fungicides, insecticides, herbicides, and plant growth regulators are basically organic molecules, whose hydroxyl and carboxyl groups can form complexes with Cu2+. As a matrix, cyclodextrin not only increases the surface area of the materials, but also provides the binding sites of hydroxyl and carboxyl groups, which guarantees efficient enrichment of Cu2+. Organic pesticides with high polarity, high electron density, and strong hydrophobicity could be better adsorbed. In this paper, the application of cyclodextrin-based adsorbents in pesticide adsorption was reviewed, and on this basis, reference to future development directions and application prospects were provided. The adsorption capacity of individual pesticide adsorbents based on cyclodextrin, as reviewed in this paper, is not high enough. Therefore, improving the adsorption capacity is currently a major research target. Some of the above-mentioned adsorbents have unclear degradation mechanisms and can easily cause secondary pollution. Therefore, the development of environment-friendly pesticide adsorbents that are easy to regenerate is a promising research direction for the future. After adsorption, some detection methods are used to determine whether the pesticide residues are up to the standard; however, the detection instruments are expensive. Therefore, the development of a combined detection mechanism that can reduce workload and cost is a promising research direction. Finally, the development of smart cyclodextrin-based adsorbents is also an efficient and rapid method to reduce the cost of detecting residual pesticide concentrations and the risk of pesticide pollution. For example, intelligent materials, whose color changes can be observed by the naked eye, not only adsorb pesticides, but also respond according to the concentration of residual pesticides.

Photocatalytic processes for biomass conversion

This review focuses on the photocatalytic conversion of biomass, emphasizing several types of systems, including different photocatalysts and biomass derivatives.

Flavonoid-sensitized photolysis of chlorothalonil in water

BACKGROUND

Chlorothalonil is a conventional chloroaromatic fungicide and is toxic to many aquatic species. This study was designed to investigate the effects of six flavonoids on the photolysis of chlorothalonil under sunlight and artificial light.

RESULTS

Flavonoids sensitized the photolysis of chlorothalonil under sunlight and artificial light by 6.7-18.3 and 2.4-7.5 times, respectively, in comparison with a flavonoid-free control. Photosensitization effect of each of the six flavonoids was greater under sunlight irradiation than under high-pressure mercury lamp irradiation. Cyanidin showed greater photosensitization effects than luteolin, galangin, quercetin, morin and kaempferol. Chlorothalonil underwent photo-reductive dechlorination and no hydrolysis product was formed in the presence of flavonoids. Hydroxyl and hydrogen radicals were detected in the absence and presence of cyanidin, respectively, under light irradiation.

CONCLUSION

The photosensitization effect of flavonoids on chlorothalonil photolysis is apparently related to flavonoid structure and might be due to their hydrogen donation capacity. These results highlight benefit of using flavonoids to manage aquatic pollution and reduce aquatic toxicity, and have great relevance in predicting the degradation kinetics and biological impacts of chlorothalonil in surface water. © 2020 Society of Chemical Industry.

Nanoparticles in Agroindustry: Applications, Toxicity, Challenges, and Trends

Nanotechnology is a tool that in the last decade has demonstrated multiple applications in several sectors, including agroindustry. There has been an advance in the development of nanoparticulated systems to be used as fertilizers, pesticides, herbicides, sensors, and quality stimulants, among other applications. The nanoencapsulation process not only protects the active ingredient but also can affect the diffusion, interaction, and activity. It is important to evaluate the negative aspects of the use of nanoparticles (NPs) in agriculture. Given the high impact of the nanoparticulated systems in the agro-industrial field, this review aims to address the effects of various nanomaterials on the morphology, metabolomics, and genetic modification of several crops.

Biodegradation of CP/TCP by a constructed microbial consortium after comparative bacterial community analysis of long-term CP domesticated activated sludge

The objective of this study was to construct a microbial consortium for effective biodegradation of chlorpyrifos (CP) and its hydrolysis product, 3,5,6-Trichloro-2-pyridinol (TCP). A activated sludge from an organophosphorus pesticide factory was domesticated under long-term (20 weeks) CP stress, and the dynamic change in bacterial communities was analyzed by high-throughput sequencing. Then, a microbial consortium MC-BSPK was constructed of Bacillus sp. MC-B, Serratia sp. MC-S, Pseudomonas sp. MC-P, and Klebsiella sp. MC-K, which were significantly enriched during the domestication process. The biodegradation capacities of the microbial consortium MC-BSPK reached 100% for CP within 9 days and 88.61% for TCP within 15 days under the optimized degradation conditions (pH 8.0 and 31 °C). High-performance liquid chromatography (HPLC) revealed that CP could be degraded by the microbial consortium MC-BSPK into TCP, probably through hydrolysis of the P-O ester bond, and further degraded into other small molecules. A bioassay revealed that the virulence of CP toward Drosophila melanogaster W1118 was clearly reduced by the microbial consortium MC-BSPK biodegradation. Thus, the easily constructed microbial consortium MC-BSPK with high CP/TCP degradation capacities has the potential for application in pesticide-contaminated bioremediation.

Use of low frequency ultrasound for water treatment: Data on azithromycin removal

Azithromycin (AZT) is a broad-spectrum antibiotic present in different aqueous matrices due to its incomplete removal using conventional water treatments. Ultrasound (US) is an advanced oxidation technology that has demonstrated its capacity to degrade different types of organic molecules due to the generation of cavitation bubbles or cavities that promote the generation of radicals.

In this paper, data regarding the use of low-frequency US (40 kHz) in the removal of AZT are presented. Tests were carried out at lab scale for 60 min considering a reaction volume of 300 mL (pollutant initial concentration 1.0 mg L⁻¹). The effect of operational parameters such as pH, ultrasound power, the presence of external agents like ferrous ions, hydrogen peroxide, and UV radiation were evaluated. In general, obtained data show that under the experimental reaction conditions, it is feasible to reach extents of AZT removal ∼50.0%, and that the presence of other species in the medium could inhibit the reaction, mainly due to scavenging effects. This information is relevant to future applications of US, at pilot or real scale, in the treatment of water with presence of AZT or similar organic pollutants.

Chemical reduction of chlorpyrifos driven by flavin mononucleotide functionalized titanium (IV) dioxide

For many decades, organohalide and organophosphate compounds have shown significant detrimental impact on the environment. Consequently, strategies for their remediation continue to be an area of emerging need. The reduction of the chlorpyrifos pesticide, a molecule that bears both organohalide and organophosphate functional groups, is an important area of investigation due to it toxic nature. In this report, we demonstrate the effectiveness of the biological molecule, flavin mononucleotide (FMN) toward chemically reducing chlorpyrifos. The FMN was found to be highly active when anchored to nanocrystalline TiO2 surfaces. The results show new directions toward the remediation of organic contaminants under mild reaction conditions.

Constructing S-doped Ni–Co LDH intercalated with Fe3O4 heterostructure photocatalysts for enhanced pesticide degradation

A S-doped Ni–Co LDH/Fe₃O₄ nanocomposite was synthesised and its photocatalytic activity was tested for the degradation of CP.

Modeling the degradation and disinfection of water pollutants by photocatalysts and composites: A critical review

Recently, a series of new photocatalysts have been developed for to combat diverse bio-recalcitrant contaminants and the inactivation of bacteria. Modeling photocatalytic processes is important to assess these materials, and to understand and optimize their performance. In this study, the recent literature is critically reviewed and analyzed to identify and compare methods of modeling photocatalytic performance. The Langmuir-Hinshelwood model (L-H) has been used in many studies to rationalize the degradation kinetics of single contaminants because it is the simplest model including both the adsorption equilibrium and degradation rates. Other studies report the development of more sophisticated variants of the L-H model that include the rates of catalyst excitation, recombination of electron-hole pairs, production of reactive oxygen species (ROS), and formation of by-products. Modified Chick-Watson (CW) and Hom models have been used by many researchers to include lag phases of bacteria in the description of disinfection kinetics. Artificial neural networks (ANNs) have been used to analyze the effects of operational conditions on photocatalyst performance. Moreover, response surface methodology (RSM) has been employed for experimental design, and optimization of operational conditions. We have reviewed and analyzed all available articles that model photocatalytic activity towards water pollution, summarized and put them in context, and recommended future research directions.

Biological Visual Detection for Advanced Photocatalytic Oxidation toward Pesticide Detoxification

Photocatalytic oxidation treatment is an emerging and fast developed eco-friendly, energy-saving, and efficient advanced oxidation technology for degrading hazardous pesticides. The conventional chemical detection to evaluate the effects for this process depends on the broken chemical structure, only giving residual content and product chemical composition. However, it misses direct visual detection on the toxicity and the quantitative analysis of pesticide detoxification. Here, we develop a novel strategy to combine photocatalytic oxidation with a zebrafish biological model to provide a direct visual detection on the environmental detoxification. The mortality or deformity of zebrafish embryos (ZEs) acts as an indicator. Over the irradiation duration threshold, the mortality of ZEs decreases to 23.3% for pure chlorothalonil (CTL-P) after photocatalytic oxidation treatment for 1 h, and the deformity reduces to 13.3% for commercial CTL (CTL-C) after 30 min and to 3.33% for tetramethylthiuram disulfide (TMTD) after 20 min. The toxicity of CTL-C and TMTD could be completely removed by photocatalytic oxidation treatment and causes no damage to the ZE developmental morphology. Chemical analyses demonstrate the degradation of CTL into inorganic compounds and TMTD into small organic molecules. Among these highlighted heterogeneous photocatalysts (g-C₃N₄, BiVO₄, Ag₃PO₄, and P25), g-C₃N₄ exhibits the highest photocatalytic detoxification for CTL-P, CTL-C, and TMTD.

Rapid Biodegradation of the Organophosphorus Insecticide Chlorpyrifos by Cupriavidus nantongensis X1T

Chlorpyrifos was one of the most widely used organophosphorus insecticides and the neurotoxicity and genotoxicity of chlorpyrifos to mammals, aquatic organisms and other non-target organisms have caused much public concern. Cupriavidus nantongensis X1^T, a type of strain of the genus Cupriavidus, is capable of efficiently degrading 200 mg/L of chlorpyrifos within 48 h. This is ~100 fold faster than Enterobacter B-14, a well-studied chlorpyrifos-degrading bacterial strain. Strain X1^T can tolerate high concentrations (500 mg/L) of chlorpyrifos over a wide range of temperatures (30–42 °C) and pH values (5–9). RT-qPCR analysis showed that the organophosphorus hydrolase (OpdB) in strain X1^T was an inducible enzyme, and the crude enzyme isolated in vitro could still maintain 75% degradation activity. Strain X1^T can simultaneously degrade chlorpyrifos and its main hydrolysate 3,5,6-trichloro-2-pyridinol. TCP could be further metabolized through stepwise oxidative dechlorination and further opening of the benzene ring to be completely degraded by the tricarboxylic acid cycle. The results provide a potential means for the remediation of chlorpyrifos- contaminated soil and water.

New Evidence of the Enhanced Elimination of a Persistent Drug Used as a Lipid Absorption Inhibitor by Advanced Oxidation with UV-A and Nanosized Catalysts

This work demonstrates new evidence of the efficient destruction and mineralization of an emergent organic pollutant using UV-A and titanium nanosized catalysts. The target compound considered in this work is the primary metabolite of a lipid regulator drug, clofibrate, identified in many studies as refractory during conventional wastewater treatment. The photocatalytic performance study was carried out in batch mode at laboratory scale, in aqueous suspension. Kinetic data showed that titanium dioxide P25 Aeroxide® exhibits the highest photocatalytic efficiency compared to the other investigated catalysts. Pollutant degradation and mineralization efficiencies strongly increased when decreasing the initial substrate concentration. Target molecules oxidized faster when the catalyst load increased, and the mineralization was enhanced under acidic conditions: 92% of mineralization was achieved at pH 4 after 190 min of reaction. Radical quenching assays confirmed that HO• and ( h vb + ) were the reactive oxygen species involved in the photocatalytic oxidation of the considered pollutant. In addition, further results revealed that the removal efficiency decreased in real water matrices. Finally, data collected through a series of phytotoxicity tests demonstrated that the photocatalytic process considerably reduces the toxicity of the treated solutions, confirming the process’s effectiveness in the removal of persistent and biorefractory emergent organic water pollutants.

Electrochemical Characterization of Mancozeb Degradation for Wastewater Treatment Using a Sensor Based on Poly (3,4-ethylenedioxythiophene) (PEDOT) Modified with Carbon Nanotubes and Gold Nanoparticles

Mancozeb is a worldwide fungicide used on a large scale in agriculture. The active component and its main metabolite, ethylene thiourea, has been related to health issues. Robust, fast, and reliable methodologies to quantify its presence in water are of great importance for environmental and health reasons. The electrochemical evaluation of mancozeb using a low-cost electrochemical electrode modified with poly (3,4-ethylene dioxythiophene), multi-walled carbon nanotubes, and gold nanoparticles is a novel strategy to provide an in-situ response for water pollution from agriculture. Additionally, the thermal-, electrochemical-, and photo-degradation of mancozeb and the production of ethylene thiourea under controlled conditions were evaluated in this research. The mancozeb solutions were characterized by electrochemical oxidation and ultraviolet-visible spectrophotometry, and the ethylene thiourea concentration was measured using ultra-high-performance liquid chromatography high-resolution mass spectrometry. The degradation study of mancozeb may provide routes for treatment in wastewater treatment plants. Therefore, a low-cost electrochemical electrode was fabricated to detect mancozeb in water with a robust electrochemical response in the linear range as well as a quick response at a reduced volume. Hence, our novel modified electrode provides a potential technique to be used in environmental monitoring for pesticide detection.

Chlorpyrifos degradation via photoreactive TiO2 nanoparticles: Assessing the impact of a multi-component degradation scenario

High concentrations of pesticides enter surface waters following agricultural application, raising environmental and human health concerns. The use of photoreactive nanoparticles has shown promise for contaminant degradation and surface water remediation. However, it remains uncertain how the complexity of natural waters will impact the photodegradation process. Here, we investigate the photoreactivity of titanium dioxide nanoparticles, the capability to degrade the pesticide chlorpyrifos, and the effect of and impact on bacteria during the photodegradation process. Loss of chlorpyrifos in solution resulted solely from photocatalytic oxidation, with 80% degradation observed after 24 h in our reactor, either in the presence or absence of bacteria. Degradation of chlorpyrifos to chlorpyrifos oxon and 3,5,6-trichloro-2-pyridinol was observed via LC/MS-MS and effectively modeled for the given reactor conditions. Bacterial inactivation occurred over 60 min and was not impacted by the presence of chlorpyrifos. The relative affinity of bacteria and chlorpyrifos for the nanoparticle surface decreased the amount of Reactive Oxygen Species (ROS) detected in the bulk by up to 94%, suggesting that ROS measurements in simplified systems may overestimate the reactivity of photoreactive nanoparticles in complex environments.

Photocatalytic Degradation of Profenofos and Triazophos Residues in the Chinese Cabbage, Brassica chinensis, Using Ce-Doped TiO2

Pesticides have revolutionized the modern day of agriculture and substantially reduced crop losses. Synthetic pesticides pose a potential risk to the ecosystem and to the non-target organisms due to their persistency and bioaccumulation in the environment. In recent years, a light-mediated advanced oxidation processes (AOPs) has been adopted to resolve pesticide residue issues in the field. Among the current available semiconductors, titanium dioxide (TiO2) is one of the most promising photocatalysts. In this study, we investigated the photocatalytic degradation of profenofos and triazophos residues in Chinese cabbage, Brassica chinensis, using a Cerium-doped nano semiconductor TiO2 (TiO2/Ce) under the field conditions. The results showed that the degradation efficiency of these organophosphate pesticides in B. chinensis was significantly enhanced in the presence of TiO2/Ce. Specifically, the reactive oxygen species (ROS) contents were significantly increased in B. chinensis with TiO2/Ce treatment, accelerating the degradation of profenofos and triazophos. Ultra-performance liquid chromatography–mass spectroscopy (UPLC-MS) analysis detected 4-bromo-2-chlorophenol and 1-phenyl-3-hydroxy-1,2,4-triazole, the major photodegradation byproducts of profenofos and triazophos, respectively. To better understand the relationship between photodegradation and the molecular structure of these organophosphate pesticides, we investigated the spatial configuration, the bond length and Mulliken atomic charge using quantum chemistry. Ab initio analysis suggests that the bonds connected by P atom of profenofos/triazophos are the initiation cleavage site for photocatalytic degradation in B. chinensis.

Photocatalytic degradation of yellow 2G dye using titanium dioxide/ultraviolet A light through a Box-Behnken experimental design: Optimization and kinetic study

Yellow 2G (Y2G), a type of anionic, synthetic monoazo dye that is widely used in household applications, textiles, and food industries, has been found to have cardiovascular and neurological effects on all living beings. In the present study, heterogeneous photocatalytic degradation of commercial Y2G was conducted using pure titanium dioxide (TiO₂) in a batch reactor system under ultraviolet A (UVA) light for 180 min. TiO₂ dosage, pH, and initial Y2G concentration were the three experimental parameters selected and studied to obtain preliminary information about the photocatalytic activities within a specified range. The Box-Behnken design method (BBD) was used to determine optimal values of the results using the above parameters of Y2G photocatalysis under response surface methodology (RSM). The optimum conditions were 0.914 g L^-1 TiO_2, pH 3.45, and an initial Y2G concentration of 20 mg L^-1. The Y2G degradation efficiency was 96.19% using a second-order polynomial equation with R² ≈ 0.999. The experimental results also showed that the photocatalytic process could be successfully explained using the modified Langmuir-Hinshelwood model, where k_c and K_LH were 0.787 mg L^-1 min and 0.010 L mg^-1, respectively.

Degradation of UV-filter Benzophenon-3 in aqueous solution using TiO2 coated on quartz tubes

BACKGROUND

Benzophenone-3 (BP-3), one of the emerging pollutants, is commercially synthesized as UV filter used in cosmetics and other personal care products and its occurrence in the aquatic environment has widely been reported. The goal of this study was to enhance an AOP method for degradation of UV filter Benzophenone-3 in aqueous solutions.

METHOD

In this study, sol-gel method was applied to synthesis TiO₂ nanoparticles. Subsequently, the nanoparticles were successfully coated on quartz tubes. The synthesized catalyst was characterized using XRD, FE-SEM and EDX analysis. Then, the efficiency of photocatalytic process using TiO₂ coated quartz tubes for BP-3 degradation from synthetic and real aqueous solution was assessed.

RESULT

The optimum contact time and solution pH for the highest BP-3 degradation in the synthetic solution were found at 15 min and 10, respectively. The maximum degradation (98%) of BP-3 by photocatalytic process was observed at 1 mg/L initial BP-3 concentration using 225 cm² of catalyst surface area. Among the three applied kinetic models, the experimental data were found to follow the first-order equation more closely with the rate constant of 0.2, 0.048 and 0.035 1/min for 1, 3 and 5 mg/L of initial BP-3 concentration, respectively. In order to investigate the potential of this process for real effluent, the treatment of swimming pool water and wastewater treatment plant was examined and BP-3 degradation close to 88% and 32.1 was achieved, respectively.

CONCLUSION

Based on the obtained data, the photocatalytic process could successfully be applied for water treatment in swimming pools and other effluent containing BP-3 with low turbidity. The advantage of this study is that the synthesized catalyst can be used repeatedly needless to remove catalyst from the treated solution. In addition, AOP_s can effectively eliminate organic compounds in aqueous phase, rather than transferring pollutants into another phase. The limitation of this study is that in solution with high turbidity photocatalytic degradation can be hampered and pre- treatment is needed to reduce turbidity.