Search Results (20)

Mycotoxins are highly toxic secondary metabolites that can pose a serious threat to food safety, human health, and the environment. As a promising detoxification method, photocatalysis has shown great potential for mycotoxin degradation due to its high efficiency, low cost, and green advantages. Heterogeneous photocatalysis using a semiconductor as a mediator is now regarded as an effective approach for mycotoxin degradation. The aim of this study was to review the recent developments, mainly in the photocatalytic degradation of mycotoxin (e.g., AFB1, FB1, DON, and ZEN). The principle, feasibility, and main semiconducting catalysts of mycotoxin photodegradation are introduced and discussed, including metal oxides (transition, noble, and rare earth metals), carbons (graphene, carbon nitride, and biochar) and other composites (MOFs and LDHs). This review will contribute to the development of semiconductor photocatalysts and photocatalytic degradation for mycotoxins decontamination. Full article

Herein, this study has examined the influence of Zn²⁺ sources during a biogenic-mediated pathway to synthesize ZnO nanoparticles with highly desirable solar-responsive catalytic properties. Salts of nitrate, acetate and chloride have been utilized. The ZnO powders underwent characterization using diverse analytical tools, including XRD, FTIR, Raman, BET, SEM, TEM with EDS/elemental mapping and UV-vis absorption/emission spectroscopic analyses. Accordingly, precursors have proved to affect crystallinity, morphology, surface characteristics, optical properties and the photocatalytic degradation of methylene blue (MB) model pollutant. It was observed that ZnO derived from zinc acetate precursor (Z-AC NPs) exhibits very fast photocatalytic degradation of MB at pH 11 with superior kinetic estimates of 0.314 min⁻¹ and t_1/2 = 2.2 min over many of recent reports. In contrast, the chloride precursor is not recommended along with the employed biogenic route. The intriguing findings could be directly correlated to the decreased crystal size, augmented surface area, the hexagonal morphology of the crystals, high potency in absorbing visible photons, high efficacy in separating photogenerated charge carriers and producing high amounts of ^•OH radicals. Further testing of Z-AC NPs in photocatalytic remediation of water samples from Dumat Aljandal Lake in Aljouf, Saudi Arabia, contaminated with MB and pyronine Y (PY) dyestuffs, showed high dye photodegradation. Therefore, this work could lead to an extremely fast avenue for decontaminating wastewater from hazmat dyestuff. Full article

Advanced Oxidation Processes (AOPs) offer promising methods for disinfection by generating radical species like hydroxyl radicals, superoxide anion radicals, and hydroxy peroxyl, which can induce oxidative stress and deactivate bacterial cells. Photocatalysis, a subset of AOPs, activates a semiconductor using specific electromagnetic wavelengths. A novel material, Cu/Cu₂O/CuO nanoparticles (NPs), was synthesized via a laser ablation protocol (using a 1064 nm wavelength laser with water as a solvent, with energy ranges of 25, 50, and 80 mJ for 10 min). The target was sintered from 100 °C to 800 °C at rates of 1.6, 1.1, and 1 °C/min. The composite phases of Cu, CuO, and Cu₂O showed enhanced photocatalytic activity under visible-light excitation at 368 nm. The size of Cu/Cu₂O/CuO NPs facilitates penetration into microorganisms, thereby improving the disinfection effect. This study contributes to synthesizing mixed copper oxides and exploring their activation as photocatalysts for cleaner surfaces. The electronic and electrochemical properties have potential applications in other fields, such as capacitor materials. The laser ablation method allowed for modification of the band gap absorption and enhancement of the catalytic properties in Cu/Cu₂O/CuO NPs compared to precursors. The disinfection of E. coli with Cu/Cu₂O/CuO systems serves as a case study demonstrating the methodology’s versatility for various applications, including disinfection against different microorganisms, both Gram-positive and Gram-negative. Full article

Photocatalysis is a prominent alternative wastewater treatment technique that has the potential to completely degrade pesticides as well as other persistent organic pollutants, leading to detoxification of wastewater and thus paving the way for its efficient reuse. In addition to the more conventional photocatalysts (e.g., TiO₂, ZnO, etc.) that utilize only UV light for activation, the interest of the scientific community has recently focused on the development and application of visible light-activated photocatalysts like g-C₃N₄. However, some disadvantages of g-C₃N₄, such as the high recombination rate of photogenerated charges, limit its utility. In this light, the present study focuses on the synthesis of WO₃ fibers/g-C₃N₄ Z-scheme heterojunctions to improve the efficiency of g-C₃N₄ towards the photocatalytic removal of the widely used insecticide clothianidin. The effect of two different g-C₃N₄ precursors (urea and thiourea) and of WO₃ fiber content on the properties of the synthesized composite materials was also investigated. All aforementioned materials were characterized by a number of techniques (XRD, SEM-EDS, ATR-FTIR, Raman spectroscopy, DRS, etc.). According to the results, mixing 6.5% ^W/_W WO₃ fibers with either urea or thiourea derived g-C₃N₄ significantly increased the photocatalytic activity of the resulting composites compared to the precursor materials. In order to further elucidate the effect of the most efficient composite photocatalyst in the degradation of clothianidin, the generated transformation products were tentatively identified through UHPLC tandem high-resolution mass spectroscopy. Finally, the detoxification effect of the most efficient process was also assessed by combining the results of an in-vitro methodology and the predictions of two in-silico tools. Full article

In the present study, the photocatalytic oxidation and detoxification of aqueous matrices contaminated with boscalid using g-C₃N₄ catalyst and UV-A light was investigated. The UV-A/g-C₃N₄ process was found to achieve higher than 83% removal of boscalid in both matrices, with h⁺ and ${\mathrm{O}}_2^{•-}$ being the main species. UHPLC-HRMS analysis allowed the identification of five TPs, while the main degradation pathways involved hydroxylation, cyclization, and dechlorination. Scenedesmus rubescens microalgae species was exposed to boscalid solutions and lake water spiked with the fungicide before the photocatalytic treatment and inhibition in the growth rate was observed. An increase in the toxicity was also observed during the first stages of the treatment. The results from the in silico study correlate with the observed evolution of ecotoxicity during the application of the process, as some of the identified TPs were found to be toxic or very toxic for aquatic organisms. However, prolonged application of the process can lead to detoxification. It was also observed that the g-C₃N₄ catalyst can retain its photochemical stability and activity after at least three cycles. However, a slight decrease in the activity was observed when repeated another two times. This study demonstrated that the suggested photocatalytic process can both decrease the harmful effects of boscalid as well as effectively lower its concentration in water. Full article

Cyanide is a highly toxic substance present in wastewater from various industries. This study investigates the removal of cyanide species (CS) from aqueous solutions using the ZnTiO₃/TiO₂/H₂O₂/UVB system. ZnTiO₃/TiO₂ nanoparticles synthesized by the sol-gel method were characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The adsorption capacity of nanoparticles was tested by varying the pH of the solution, adsorbent concentration, and contact time. The adsorption of CS on ZnTiO₃ and TiO₂ surfaces was verified by Density Functional Theory (DFT) calculations. Photocatalytic experiments were achieved under UVB irradiation (λ = 310 nm). The response surface methodology (RSM) was used to optimize the CS removal efficiency. The detoxification effect was evaluated by acute toxicity tests with brine shrimp. The theoretical results show that the adsorption of CS is energetically more favorable on the ZnTiO₃ surface than on the TiO₂ surface. The experimental results show that the system consisting of ZnTiO₃/TiO₂ (200 mg L⁻¹), H₂O₂ (0.1%), and UVB light removes 99% of CS from aqueous solutions after 60 min and reduces the mortality of nauplii in 90% after 90 min. This system was reused in five consecutive cycles with a total loss of efficiency of 30%. Full article

The photocatalytic degradation of Acid Red 26 was examined utilizing a graphitic carbon nitride (g-C₃N₄) catalyst and a UV-A light in this study. We investigated how successfully the photocatalytic approach removed Acid Red 26 from synthetic and actual municipal wastewater. Both aqueous matrices allowed for extremely high clearance rates. Wastewater degraded at a slower rate than the other matrices, this might be ascribed to the wastewater’s complicated chemical composition. Using a liquid chromatography-mass spectrometry (LC-MS), the IPs in both synthetic and actual municipal effluent were determined. The photocatalytic degradation mechanisms of Acid Red 26 are hypothesised to comprise oxidation, dealkylation, and methoxy group cleavage based on the observed intermediate products (IPs). Using proven scavengers, we were also able to investigate the role of reactive species in the degradation process and illustrate the significance of h⁺ and O₂^• in the reaction. Chlorococcum sp. and Dunaliella tertiolecta microalgae were also utilised to assess the development of ecotoxicity. We observed low toxicity throughout the process when clean water was used as the matrix, with no production of hazardous IPs. In the case of actual municipal wastewater, there was an early rise in toxicity, which scientists believe was caused by the matrix’s chemical make-up. To lower the toxicity, a heterogeneous photocatalysis was used, and at the end of the treatment, nearly full detoxification was obtained. Full article

Targeting heterostructures with modulated electronic structures and efficient charge carrier separation and mobility is an effective strategy to improve photocatalytic performance. In this study, we report the synthesis of 2D/3D hybrid heterostructures comprising P-doped graphitic carbon nitride (g-C₃N₄) nanosheets (ca. 50–60 nm in lateral size) and small-sized Ni₂P nanoparticles (ca. 10–12 nm in diameter) and demonstrate their prominent activity in the photocatalytic reduction of Cr(VI). Utilizing a combination of spectroscopic and electrochemical characterization techniques, we unveil the reasons behind the distinct photochemical performance of these materials. We show that Ni₂P modification and P doping of the g-C₃N₄ effectively improve the charge-carrier transportation and spatial separation through the interface of Ni₂P/P-doped g-C₃N₄ junctions. As a result, the catalyst containing 15 wt.% Ni₂P exhibits superior photocatalytic activity in the detoxification of Cr(VI)-contaminated effluents under UV-visible light illumination, presenting an apparent quantum yield (QY) of 12.5% at 410 nm, notably without the use of sacrificial additives. This study marks a forward step in understanding and fabricating cost-effective photocatalysts for photochemical applications. Full article

This study explores the photocatalytic transformation of the antiviral drug abacavir employing different advanced oxidation processes (AOPs) such as UV/TiO₂, UV/MOF/H₂O₂, UV/MOF/S₂O₈²⁻, UV/Fe²⁺/H₂O₂, and UV/Fe²⁺/S²O₈²⁻. All processes appear to be effective in eliminating abacavir within a few minutes, while the evolution profile of the basic transformation product, descyclopropyl-abacavir (TP-247) was also monitored. Moreover, the implementation of the most efficient technologies towards the removal of abacavir in different matrices such as wastewater effluent and leachate was also assessed, revealing that the organic matter present or the inorganic constituents can retard the whole process. Four major transformation products were detected, and their time-evolution profiles were recorded in all studied matrices, revealing that different transformation pathways dominate in each matrix. Finally, the prediction of the toxicity of the major TPs employing ECOSAR software was conducted and showed that only hydroxylation can play a detoxification role in the treated solution. Full article

In the present study, the photocatalytic degradation of amisulpride using g-C₃N₄ catalyst under UV-A irradiation was investigated. The photocatalytic process was evaluated in terms of its effectiveness to remove amisulpride from ultrapure and real municipal wastewater. High removal percentages were achieved in both aqueous matrices. However, a slower degradation rate was observed using wastewater as matrix that could be attributed to its complex chemical composition. The transformation products (TPs) were identified with liquid chromatography–mass spectrometry (LC–MS) in both ultrapure and real municipal wastewater. Based on the identified TPs, the photocatalytic degradation pathways of amisulpride are proposed which include mainly oxidation, dealkylation, and cleavage of the methoxy group. Moreover, the contribution of reactive species to the degradation mechanism was studied using well-documented scavengers, and the significant role of h⁺ and O₂^•− in the reaction mechanism was proved. The evolution of ecotoxicity was also estimated using microalgae Chlorococcum sp. and Dunaliella tertiolecta. Low toxicity was observed during the overall process without the formation of toxic TPs when ultrapure water was used as matrix. In the case of real municipal wastewater, an increased toxicity was observed at the beginning of the process which is attributed to the composition of the matrix. The application of heterogeneous photocatalysis reduced the toxicity, and almost complete detoxification was achieved at the end of the process. Our results are in accordance with literature data that reported that heterogeneous photocatalysis is effective for the removal of amisulpride from aqueous matrices. Full article

The contamination of organic dye molecules in aquatic environments caused by the effluents released from vast industrial establishments has been a matter of serious concern in recent years, owing to their strong non-biodegradable nature and acute toxicity. Semiconductor-mediated visible-light-driven photocatalytic-dye detoxification is considered as a sustainable technique because it abundantly utilizes the available solar energy and releases environmentally friendly chemicals such as H₂O as byproducts. Adequate textural and microstructural properties, an extended visible-light response, pronounced isolation and transfer of photoinduced charge carriers, and facile magnetic-separation characteristics make spinel-ferrite-decorated graphene or its analogues’ (GO/rGO) nanocomposites (MFGNs) a versatile photocatalytic system for the efficacious detoxification of dyes. Therefore, this review article emphasizes their exceptional photodegradation performance in terms of systematic studies of the above-mentioned features, after a brief description of the synthesis protocols. The mechanism of the photodetoxification of dyes over MFGNs is precisely demonstrated in three different sections based on their redox abilities. The kinetics of the MFGN-driven photodecomposition of dyes are then highlighted. We discuss the role of different parameters such as pH, temperature, catalyst dose, and dye concentration in augmented photocatalytic-dye-degradation reactions. Finally, the emerging challenges that act as hurdles in achieving superior photocatalytic-dye-detoxification performance are addressed, along with the conclusion. We then propose some possible future research directions in order to overcome these challenges, for impressively accomplishing the photodegradation of organic dyes. Full article

The complete detoxification of harmful dyes and antibiotics from aqueous solution is essential for environmental remediation. The present work focuses on a facile hydrothermal synthesis of a cadmium sulfide (CdS) photocatalyst using thioacetamide as a sulfur source. The synthesized CdS showed a hexagonal phase with an energy gap of 2.27 eV, suggesting the promising visible-light-responsive semiconducting photocatalyst. The photoactivity of the prepared CdS was investigated by evaluating the degradation of the Reactive red 141 (RR141) dye, Congo red (CR) dye, and ofloxacin (OFL) antibiotic. After only 180 min of solar light illumination, a high performance of 98%, 97%, and 87% toward degradation of RR141, CR, and OFL was obtained. The photodegradation of the pollutants agrees well with the first-order kinetic model. The rate constant of 0.055 min⁻¹, 0.040 min⁻¹, and 0.026 min⁻¹, respectively, was reported toward degradation of RR141, CR, and OFL. Photogenerated holes and hydroxyl radicals play a vital role in removing toxic organic contaminants. The chemical stability of the prepared CdS was also confirmed. The synthesized CdS photocatalyst still maintains high photocatalytic performance even after five consecutive cycles of use, indicating its excellent cycling ability. The present research shows a facile route to fabricate a CdS photocatalyst to completely detoxify harmful organic pollutants, including dyes and antibiotics, in the environment. Full article

Advanced oxidation processes (AOPs) have been introduced to deal with different types of water pollution. They cause effective chemical destruction of pollutants, yet leading to a mixture of transformation by-products, rather than complete mineralization. Therefore, the aim of our study was to understand complex degradation processes induced by different AOPs from chemical and ecotoxicological point of view. Phenol, 2,4-dichlorophenol, and pentachlorophenol were used as model pollutants since they are still common industrial chemicals and thus encountered in the aquatic environment. A comprehensive study of efficiency of several AOPs was undertaken by using instrumental analyses along with ecotoxicological assessment. Four approaches were compared: ozonation, photocatalytic oxidation with immobilized nitrogen-doped TiO₂ thin films, the sequence of both, as well as electrooxidation on boron-doped diamond (BDD) and mixed metal oxide (MMO) anodes. The monitored parameters were: removal of target phenols, dechlorination, transformation products, and ecotoxicological impact. Therefore, HPLC–DAD, GC–MS, UHPLC–MS/MS, ion chromatography, and 48 h inhibition tests on Daphnia magna were applied. In addition, pH and total organic carbon (TOC) were measured. Results show that ozonation provides by far the most suitable pattern of degradation accompanied by rapid detoxification. In contrast, photocatalysis was found to be slow and mild, marked by the accumulation of aromatic products. Preozonation reinforces the photocatalytic process. Regarding the electrooxidations, BDD is more effective than MMO, while the degradation pattern and transformation products formed depend on supporting electrolyte. Full article

In this study, a novel photoelectrocatalytic membrane (PECM) reactor was tested as an option for the desalination, disinfection, and detoxification of biologically treated textile wastewater (BTTWW), with the aim to reuse it in hydroponic farming. The anionic ion exchange (IEX) process was used before PECM treatment to remove toxic residual dyes. The toxicity evaluation for every effluent was carried out using the Vibrio fischeri, Microtox^® test protocol. The disinfection effect of the PECM reactor was studied against E. coli. After PECM treatment, the 78.7% toxicity level of the BTTWW was reduced to 14.6%. However, photocatalytic desalination during treatment was found to be slow (2.5 mg L⁻¹ min⁻¹ at 1 V potential). The reactor demonstrated approximately 52% COD and 63% TOC removal efficiency. The effects of wastewater reuse on hydroponic production were comparatively investigated by following the growth of the lettuce plant. A detrimental effect was observed on the lettuce plant by the reuse of BTTWW, while no negative impact was reported using the PECM treated textile wastewater. In addition, all macro/micronutrient elements in the PECM treated textile wastewater were recovered by hydroponic farming, and the PECM treatment may be an eco-safe wastewater reuse method for crop irrigation. Full article

The present study was performed to fabricate a titanium dioxide (TiO₂) nanocatalyst with proper characteristics for the removal of some insecticides (dimethoate and methomyl) from aqueous media. A TiO₂ catalyst of regular (TiO₂—commercial—/H₂O₂/UV) or nano (TiO₂—synthesized—/H₂O₂/UV) size was employed as an advanced oxidation process by combining it with H₂O₂ under light. Moreover, the total detoxification of insecticides after treatment with the most effective system (TiO₂(s)/H₂O₂/UV) was also investigated through exploring the biochemical alterations and histopathological changes in the liver and kidneys of the treated rats. Interestingly, the present study reported that degradation rates of the examined insecticides were faster using the TiO₂ catalyst of nano size. Complete degradation of the tested insecticides (100%) was achieved under the TiO₂(s)/H₂O₂/UV system after 320 min of irradiation. The half-life values of the tested insecticides under H₂O₂/TiO₂(c)/UV were 43.86 and 36.28 for dimethoate and methomyl, respectively, whereas under the H₂O₂/TiO₂(c)/UV system, the half-life values were 27.72 and 19.52 min for dimethoate and methomyl, respectively. On the other hand, no significant changes were observed in the biochemical and histopathological parameters of rats administrated with water treated with TiO₂(s)/H₂O₂/UV compared to the control, indicating low toxicity of the TiO₂ nanocatalyst-. Altogether, the advanced oxidation processes using TiO₂ nanocatalyst can be considered as a promising and effective remediation technology for the complete detoxification of methomyl and dimethoate in water. However, further future research is needed to identify the possible breakdown products and to verify the safety of the used nanomaterials. Full article