Pesticide decontamination using UV/ferrous-activated persulfate with the aid neuro-fuzzy modeling: A case study of Malathion

Carbon-dot-induced oxygen vacancies in copper vanadate enabling persulfate photoactivation for tetracycline degradation

Synchronously creating oxygen vacancies (OVs) and an internal electric field (IEF) in photocatalysts could be an ideal strategy to facilitate photogenerated charge separation and surface reactions but remain unexplored for this use. In this work, we report that low-cost and multifunctional CDs can involve in the nucleation reaction of copper vanadates (CuVs) to create OVs and proper IEF at the interface by modulating the valence states of coppers under hydrothermal conditions. Thus, CDs synergistically serve as oxygen vacancy inducer and charge separator in CuVs to extract photogenerated carriers to trigger persulfate (PS) activation for the degradation of tetracycline hydrochloride (TC). It turns out that CDs-modulated CuVs exhibit the expected photocatalytic capacity to activate PS in water and enable TC decomposition efficiency approximately 8 times higher than CDs-free CuVs under visible light irradiation. Our investigations elucidate that the oxidative breakdown of TC is dominated by the active species cooperation of 1O2 with h+ and OH formed in photocatalytic reaction system.

Environmental health risk assessment of chlorpyrifos near a pesticide enterprise in East China

This study presents the results of an environment investigation and monitoring of chlorpyrifos contamination in the vicinity of a pesticide enterprise in East China, focusing on its relation to environmental and human health risks. The impact zone of chlorpyrifos is particularly pronounced within approximately 2 km of the enterprise. The highest levels of outdoor dust were observed in SP1, which is closest to the enterprise. The individual health risk of exposure to chlorpyrifos through different media - such as indoor air, rice, vegetables, drinking water and indoor dust - was assessed following the procedure defined by the USEPA. The non-carcinogenic risks to both adults and children do not exceed the permissible standard of 1, suggesting no non-carcinogenic risks due to chlorpyrifos exposure. However, the average daily dose calculated by exposure assessment model shows that children are exposed to higher doses of chlorpyrifos compared to adults due to their lifestyle habits and play patterns.

Consumer Safety and Pesticide Residues: Evaluating Mitigation Protocols for Greengrocery

The application of pesticides remains a necessary measure for pest management in agriculture, particularly in the cultivation of fruits and vegetables. After harvest, the presence of pesticide residues in greengrocery (fruits and vegetables) is significantly influenced by various factors, including storage conditions, handling practices, and subsequent processing methods. The mitigation of these residues to levels compliant with regulated maximum thresholds ensures the safety of raw and processed fruits and vegetables for consumption. A contemporary survey of pesticide residues in greengrocery has gathered considerable attention from consumers, driven by concerns over the potential health risk of pesticide exposure. Consequently, consumers want to be extensively informed about household processing techniques to minimize associated risks. Meanwhile, a critical question arises: does household processing effectively eliminate pesticide residues? A comprehensive review of the literature reveals that conventional methods, such as washing and soaking, offer only limited reduction in residue levels, while emerging treatments, suitable both at household and industrial scale, demonstrate increased efficiency in residues mitigation. This study aims to emphasise the ubiquitous use of pesticides in crop cultivation while providing recommendations for the implementation of efficient treatment protocols to address residue concerns. Following upon available evidence and database mining, the worldwide purpose must be to outline agriculturally and economically viable strategies that prioritize both the health and safety of consumers, as well as the green cultivation and processing of fruits and vegetables.

Application and innovation of artificial intelligence models in wastewater treatment

At present, as the problem of water shortage and pollution is growing serious, it is particularly important to understand the recycling and treatment of wastewater. Artificial intelligence (AI) technology is characterized by reliable mapping of nonlinear behaviors between input and output of experimental data, and thus single/integrated AI model algorithms for predicting different pollutants or water quality parameters have become a popular method for simulating the process of wastewater treatment. Many AI models have successfully predicted the removal effects of pollutants in different wastewater treatment processes. Therefore, this paper reviews the applications of artificial intelligence technologies such as artificial neural networks (ANN), adaptive network-based fuzzy inference system (ANFIS) and support vector machine (SVM). Meanwhile, this review mainly introduces the effectiveness and limitations of artificial intelligence technology in predicting different pollutants (dyes, heavy metal ions, antibiotics, etc.) and different water quality parameters such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) in wastewater treatment process, involving single AI model and integrated AI model. Finally, the problems that need further research together with challenges ahead in the application of artificial intelligence models in the field of environment are discussed and presented.

Harnessing artificial intelligence-driven approach for enhanced indole-3-acetic acid from the newly isolated Streptomyces rutgersensis AW08

Indole-3-acetic acid (IAA) derived from Actinobacteria fermentations on agro-wastes constitutes a safer and low-cost alternative to synthetic IAA. This study aims to select a high IAA-producing Streptomyces-like strain isolated from Lake Oubeira sediments (El Kala, Algeria) for further investigations (i.e., 16S rRNA gene barcoding and process optimization). Subsequently, artificial intelligence-based approaches were employed to maximize IAA bioproduction on spent coffee grounds as high-value-added feedstock. The specificity was the novel application of the Limited-Memory Broyden-Fletcher-Goldfarb-Shanno Box (L-BFGS-B) optimization algorithm. The new strain AW08 was a significant producer of IAA (26.116 ± 0.61 μg/mL) and was identified as Streptomyces rutgersensis by 16S rRNA gene barcoding and phylogenetic inquiry. The empirical data involved the inoculation of AW08 in various cultural conditions according to a four-factor Box Behnken Design matrix (BBD) of Response surface methodology (RSM). The input parameters and regression equation extracted from the RSM-BBD were the basis for implementing and training the L-BFGS-B algorithm. Upon training the model, the optimal conditions suggested by the BBD and L-BFGS-B algorithm were, respectively, L-Trp (X1) = 0.58 %; 0.57 %; T° (X2) = 26.37 °C; 28.19 °C; pH (X3) = 7.75; 8.59; and carbon source (X4) = 30 %; 33.29 %, with the predicted response IAA (Y) = 152.8; 169.18 μg/mL). Our findings emphasize the potential of the multifunctional S. rutgersensis AW08, isolated and reported for the first time in Algeria, as a robust producer of IAA. Validation investigations using the bioprocess parameters provided by the L-BFGS-B and the BBD-RSM models demonstrate the effectiveness of AI-driven optimization in maximizing IAA output by 5.43-fold and 4.2-fold, respectively. This study constitutes the first paper reporting a novel interdisciplinary approach and providing insights into biotechnological advancements. These results support for the first time a reasonable approach for valorizing spent coffee grounds as feedstock for sustainable and economic IAA production from S. rutgersensis AW08.

Environmental carrying capacity and ecological risk assessment of pesticides under different soil use types in the Central Plains Urban Agglomeration (CPUA), China

Soil environmental safety has received much attention during the past few decades due to its significance in agricultural production and human health. Special attention is required for soil pesticide residues and ecological risks. This study examined 197 soil samples from industrial, residential and agricultural areas for the presence of 12 organophosphorus pesticides (OPPs) and 8 synthetic pyrethroids (SYPs) in the 16 cities in Henan Province, and the center of CPUA, based on the Central Plains Urban Agglomeration (CPUA) concept proposed by China. The total average concentrations of ∑12OPPs in industrial, residential and agricultural soils were 194, 217, 267 ng/g dry weight, and those of ∑8SYPs were 26.8, 35.7, 25.5 ng/g dry weight, respectively. The two pollutants with the greatest concentrations in the soils were malathion and fenpropathrin, respectively, the dominant components of OPPs and SYPs. The soil environmental carrying capacity (SECC) analysis, representing the maximum residual load that can be supported, shows that acephate and cyhalothrin were overloaded, with a predicted period of over 500 years. Among the 16 cities of CPUA, a higher frequency of high ecological risk could be observed only in Shangqiu. The OPPs in children had total non-carcinogenic risk values of more than 1.0. Similarly, the non-carcinogenic risks of SYPs in adults and children in the residential areas were more than 1.0. The study provides knowledge on how to effectively manage soil safety in Henan Province, which is the center of the CPUA, with a large population and grain province to protect ecosystems and reduce the risks of soil pesticide residues in humans.

Sustainable degradation of pollutants, generation of electricity and hydrogen evolution via photocatalytic fuel cells: An Inclusive Review

Environmental pollution and energy crisis have recently become one of the major global concerns. Insincere discharge of massive amount of organic and inorganic wastes into the aqueous bodies causes serious impact on our environment. However, these organic substances are significant sources of carbon and energy that could be sustainably utilized rather than being discarded. Photocatalytic fuel cell (PFC) is a smart and novel energy conversion device that has the ability to achieve dual benefits: degrading the organic contaminants and simultaneously generating electricity, thereby helping in environmental remediation. This article presents a detailed study of the recent advancements in the development of PFC systems and focuses on the fundamental working principles of PFCs. The degradation of various common organic and inorganic contaminants including dyes and antibiotics with simultaneous power generation and hydrogen evolution has been outlined. The impact of various operational factors on the PFC activity has also been briefly discussed. Moreover, it provides an overview of the design guidelines of the different PFC systems that has been developed recently. It also includes a mention of the materials employed for the construction of the photo electrodes and highlights the major limitations and relevant research scopes that are anticipated to be of interest in the days to come. The review is intended to serve as a handy resource for researchers and budding scientists opting to work in this area of PFC devices.

Significantly activated persulfate by novel carbon quantum dots-modified N-BiOCl for complete degradation of bisphenol-A under visible light irradiation

The practical application of bismuth-based photocatalysts in the field of micropollutant photodegradation is limited due to their weak light absorption and rapid charge recombination. Herein, we have developed a novel carbon quantum dots-modified N-BiOCl (CDs-N-BiOCl) photocatalyst to activate persulfate (PS) for the complete elimination of endocrine-disruptor bisphenol A (BPA) under visible light irradiation. The photoelectric properties characterization shows that N atoms could replace Cl atoms or adsorb on Bi atoms to form local N 1s states in the BiOCl lattice, accompanied by the introduction of doping energy levels that shorten the electron migration distance. Meanwhile, the decorated CDs could effectively accept the photoinduced electrons from N-BiOCl conduction band to facilitate the charge separation. Thus, the 7%CDs-N-BiOCl (7CNB) nanocomposite synergistically activated PS realized rapid and effective degradation of BPA within 20 min (degradation efficiency and mineralization reached 100 % and 66.4 % respectively). Moreover, the 7CNB/PS system displayed favorable adaptability, durability, and interference resistance. Furthermore, the biotoxicity experiments demonstrated that the photodegradation intermediates promoted the growth of Escherichia coli which indicates its eco-friendliness for practical application. Finally, the electron transfer mechanism and the formation of reactive oxygen species in the photodegradation process were interpreted. In short, this work will present a promising strategy for bismuth-based photocatalysts to be used for the efficient treatment of real water bodies under visible light irradiation.

Mechanism and Kinetics of Prothioconazole Photodegradation in Aqueous Solution

This study investigated the effects of light source, pH value, and NO₃^- concentration on the photodegradation of prothioconazole in aqueous solution. The half-life (t_1/2) of prothioconazole was 173.29, 21.66, and 11.18 min under xenon, ultraviolet, and high-pressure mercury lamps, respectively. At pH values of 4.0, 7.0, and 9.0 under a xenon lamp light source, the t_1/2 values were 693.15, 231.05, and 99.02 min, respectively. Inorganic substance NO₃^- clearly promoted the photodegradation of prothioconazole, with t_1/2 values of 115.53, 77.02, and 69.32 min at NO₃^- concentrations of 1.0, 2.0, and 5.0 mg L^-1, respectively. The photodegradation products were identified as C₁₄H₁₅Cl₂N₃O, C₁₄H₁₆ClN₃OS, C₁₄H₁₅Cl₂N₃O₂S, and C₁₄H₁₃Cl₂N₃ based on calculations and the Waters compound library. Furthermore, density functional theory (DFT) calculations showed that the C-S, C-Cl, C-N, and C-O bonds of prothioconazole were the reaction sites with high absolute charge values and greater bond lengths. Finally, the photodegradation pathway of prothioconazole was concluded, and the variation in energy of the photodegradation process was attributed to the decrease in activation energy caused by light excitation. This work provides new insight into the structural modification and photochemical stability improvement of prothioconazole, which plays an important role in decreasing safety risk during application that will reduce the exposure risk in field environment.

Phenol red dye removal from wastewater using TiO2-FSM-16 and Ni-FSM-16 photocatalysts

In this study, the performance of Ni-FSM-16 and TiO₂-FSM-16 photocatalysts in phenol red removal was explored. The XRD, FE-SEM, and BET tests were used to characterize the catalysts. All experiments were performed at ambient temperature and under UV (20 W). The parameters including dye concentration (20-80 mg/L), photocatalyst concentration (0-8 g/L), UV exposure duration, and contact time (0-160 min) were optimized using RSM software. BET values of Ni-FSM-16 and TiO₂-FSM-16 were 718.63 m²/g and 844.93 m²/g, respectively. TiO₂-FSM-16 showed better performance in dye removal than Ni-FSM-16. At pH 3, the maximum dye removal by TiO₂-FSM-16/UV and Ni-FSM-16/UV was obtained 87% and 64%, respectively. The positive hole species had the main role in photocatalytic phenol red removal. The reusability study was done for up to 7 cycles, but the catalysts can be reused effectively for up to 3 cycles. The synergistic factor for the TiO₂-FSM-16 and TiO₂-FSM-16/UV processes were calculated to be 1.55 and 2.12, respectively. The dye removal efficiency by TiO₂-carbon and Ni-carbon was slightly lower than those obtained by the FSM-16 ones. The TiO₂-FSM-16 and Ni-FSM-16 catalysts had a suitable surface and acceptable efficiency in phenol red removal.

NiFe2O4/g-C3N4 heterostructure with an enhanced ability for photocatalytic degradation of tetracycline hydrochloride and antibacterial performance

In this work, NiFe₂O₄/g-C₃N₄ heterostructure was prepared and used for the photocatalytic decomposition of tetracycline hydrochloride antibiotic and for inactivation of E. coli bacteria. The fabricated NiFe₂O₄/g-C₃N₄ composite displayed enhanced ability for photodegradation of organic pollutants and disinfection activities compared to the bare samples, because of the enhancement of visible light absorbance, heterojunction formation and photo-Fenton process. The optimized sample 10%-NiFe₂O₄/g-C₃N₄ has photodegraded 94.5% of tetracycline hydrochloride in 80 min. The active species trapping experiments revels that ·O₂^-, h⁺ and •OH are key decomposing species participated in the antibiotic degradation. It is hoped that the present study will provide a better understanding to fabricate efficient photocatalysts for the decomposition of organic pollutants and disinfection of bacteria.

A review of radical and non-radical degradation of amoxicillin by using different oxidation process systems

Pharmaceutical compounds have piqued the interest of researchers due to an increase in their demand, which increases the possibility of leakage into the environment. Amoxicillin (AMX) is a penicillin derivative used for the treatment of infections caused by gram-positive bacteria. AMX has a low metabolic rate in the human body, and around 80-90% is unmetabolized. As a result, AMX residuals should be treated immediately to avoid further accumulation in the environment. Advanced oxidation process techniques are an efficient way to degrade AMX. This review attempts to collect, organize, summarize, and analyze the most up to date research linked to the degradation of AMX by different advanced oxidation process systems including photocatalytic, ultrasonic, electro-oxidation, and advanced oxidation process-based on partials. The main topics investigated in this review are degradation mechanism, degradation efficiency, catalyst stability, the formation of AMX by-products and its toxicity, in addition, the influence of different experimental conditions was discussed such as pH, temperature, scavengers, the concentration of amoxicillin, oxidants, catalyst, and doping ratio. The degradation of AMX could be inhibited by very high values of pH, temperature, AMX concentration, oxidants concentration, catalyst concentration, and doping ratio. Several AMX by-products were discovered after oxidation treatment, and several of them had lower or same values of LC₅₀ (96 h) fathead minnow of AMX itself, such as m/z 384, 375, 349, 323, 324, 321, 318, with prediction values of 0.70, 1.10, 1.10 0.42, 0.42, 0.42, and 0.42 mg/L, respectively. We revealed that there is no silver bullet system to oxidize AMX from an aqueous medium. However, it is recommended to apply hybrid systems such as Photo-electro, Photo-Fenton, Electro-Fenton, etc. Hybrid systems are capable to cover the drawbacks of the single system. This review may provide important information, as well as future recommendations, for future researchers interested in treating AMX using various AOP systems, allowing them to improve the applicability of their systems and successfully oxidize AMX from an aqueous medium.

Direct red 89 dye degradation by advanced oxidation process using sulfite and zero valent under ultraviolet irradiation: Toxicity assessment and adaptive neuro-fuzzy inference systems modeling

Sulfate-based advanced oxidation process mediated by zero-valent iron (ZVI) and ultraviolet radiation for the decomposition of sulfite salts resulted in the formation of strong oxidizing species (sulfate and hydroxide radicals) in aqueous solution is reported. Degradation of direct red 89 (DR89) dye via UV/ZVI/sulfite process was systematically investigated to evaluate the effect of pH, ZVI dose, sulfite, initial DR89 concentration, and reaction time on DR89 degradation. The synergy factor of UV/ZVI/sulfite process was found to be 2.23-times higher than the individual processes including ZVI, sulfite and UV. By increasing the ZVI dose from 100 mg/L to 300 mg/L, dye degradation was linearly enhanced from 67.12 ± 3.36% to 82.40 ± 4.12% by the UV/ZVI/sulfite process due to enhanced ZVI corrosion and sulfite activation. The highest degradation efficiency of 99.61 ± 0.02% was observed at pH of 5.0, [ZVI]₀ = 300 mg/L, and [sulfite]₀ = 400 mg/L. Toxicity assessment by Lepidium sativum demonstrated that treated dye solution by UV/ZVI/sulfite was within the non-toxic range. The application of optimal adaptive neuro-fuzzy inference system (ANFIS) to predict DR89 degradation indicated high accuracy of ANFIS model (R² = 0.97 and RMSE = 0.051) via the UV/ZVI/sulfite process. It is suggested that UV/ZVI/sulfite process is suitable for industrial wastewater treatment.

Towards a comprehensive understanding of malathion degradation: comparison of degradation reactions under alkaline and radical conditions

Malathion is a commercially available insecticide that functions by acting as an acetylcholinesterase inhibitor. Of significant concern, if left in the environment, some of the products observed from the degradation of malathion can function as more potent toxins than the parent compound. Accordingly, there are numerous studies revolving around possible degradation strategies to remove malathion from various environmental media. One of the possible approaches is the degradation of malathion by OH˙ radicals which could be produced from both artificial and biological means in the environment. While there is plenty of evidence that OH˙ does in fact degrade malathion, there is little understanding of the underlying mechanism by which OH˙ reacts with malathion. Moreover, it is not known how competitive the radical degradation pathway is with analogous alkaline degradation pathways. Even less is known about the reaction of additional OH˙ radicals with the degradation byproducts themselves. Herein, we demonstrate that OH˙ induced degradation pathways have variable competitiveness with OH^- driven degradation pathways and, in some cases, produce quite different reactivity.

Efficient ofloxacin degradation via photo-Fenton process over eco-friendly MIL-88A(Fe): Performance, degradation pathways, intermediate library establishment and toxicity evaluation

The high-throughput production of the eco-friendly MIL-88A(Fe) was achieved under mild reaction conditions with normal pressure and temperature. The as-prepared MIL-88A(Fe) exhibited efficient photo-Fenton catalytic ofloxacin (OFL) degradation upon visible light irradiation with good stability and reusability. The OFL (20.0 mg/L) was completely degraded within 50 min under visible light with the aid of MIL-88A(Fe) (0.25 g/L) and H₂O₂ (1.0 mL/L) in aqueous solution (pH = 7.0). The hydroxyl radicals (·OH) are the main active species during the photo-Fenton oxidation process. Meanwhile, the degradation intermediates and the corresponding degradation pathways were identified and proposed with the aid of both ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and density functional theory (DFT) calculations. Finally, the degradation product library was firstly established to identify intermediate transformation products (TPs) with their variation of concentration, and their corresponding toxicologic activities were assessed via Toxtree and T.E.S.T software as well. Finally, the MIL-88A is efficient and stable with four cycles' catalysis operations, demonstrating good potential for water treatment.

Application of sulfate radicals-based advanced oxidation technology in degradation of trace organic contaminants (TrOCs): Recent advances and prospects

The large amount of trace organic contaminants (TrOCs) in wastewater has caused serious impacts on human health. In the past few years, Sulfate radical (SO₄^•-) based advanced oxidation processes (SR-AOPs) are widely recognized for their high removal rates of recalcitrant TrOCs from water. Peroxymonosulfate (PMS) and persulfate (PS) are stable and non-toxic strong oxidizing oxidants and can act as excellent SO₄^•- precursors. Compared with hydroxyl radicals(·OH)-based methods, SR-AOPs have a series of advantages, such as long half-life and wide pH range, the oxidation capacity of SO₄^•- approaches or even exceeds that of ·OH under suitable conditions. In this review, we present the progress of activating PS/PMS to remove TrOCs by different methods. These methods include activation by transition metal, ultrasound, UV, etc. Possible activation mechanisms and influencing factors such as pH during the activation are discussed. Finally, future activation studies of PS/PMS are summarized and prospected. This review summarizes previous experiences and presents the current status of SR-AOPs application for TrOCs removal. Misconceptions in research are avoided and a research basis for the removal of TrOCs is provided.

Determination of pesticide residues in rooibos (Aspalathus linearis) teas in South Africa

An efficient gas chromatography-mass spectrometry approach was used in this study to quantify 13 pesticide residues in rooibos teas purchased from registered retail outlets in South Africa between November 2019 and April 2020. A QuEChERS (Quick, easy, cheap, effective, rugged, and safe) procedure was used to extract pesticides using 7.5 mg of graphitized carbon black (GCB), 50 mg of primary secondary amine (PSA), and 150 mg of anhydrous MgSO4. In order to compensate for the matrix effect, matrix matched calibration curves ranging from 10 µg/kg-500 µg/kg were applied for accurate quantification. For validation purposes, accuracy tests were conducted using a blank tea sample spiked with pesticide standards at two different concentrations (10 and 100 μg/kg). Most of the analytes were recovered within acceptable recovery ranges (72-106%), with a relative standard deviation of less than 20%. The limits of quantification were low, all falling below 10 μg/kg which meets the maximum residue limits (MRLs). The validated method was used to analyze 100 tea samples, and among the pesticides analyzed, deltamethrin and lambda-cyhalothrin were detected in only one samples at a concentration (92.11 and 66.41 μg/kg, respectively) below the MRLs stipulated by the European Union. The level of pesticides that are commonly used in tea should be checked often.

MXene-based electrochemical sensors for detection of environmental pollutants: A comprehensive review

Since the discovery of MXenes at Drexel University in the United States in 2011, there has been extensive research regarding various applications of MXenes including environmental remediation. MXenes with a general formula of M_n+1X_nT_x are a class of two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides with unique chemical and physical characteristics as nanomaterials. MXenes feature characteristics such as high conductivity, hydrophobicity, and large specific surface areas that are attracting attention from researchers in many fields including environmental water engineering such as desalination and wastewater treatment as well as designing and building efficient sensors to detect hazardous pollutants in water. In this study, we review recent developments in MXene-based nanocomposites for electrochemical (bio) sensing with a particular focus on the detection of hazardous pollutants, such as organic components, pesticides, nitrite, and heavy metals. Integration of these 2D materials in electrochemical enzyme-based and affinity-based biosensors for environmental pollutants is also discussed. In addition, a summary of the key challenges and future remarks are presented. Although this field is relatively new, future research on biosensors of MXene-based nanocomposites need to exploit the remarkable properties of these 2D materials.

A global systematic review of the concentrations of Malathion in water matrices: Meta-analysis, and probabilistic risk assessment

Pesticide applications and the proximity of land use to water matrices have resulted in discharges of pollutants including Malathion -one of the most widely used organophosphorus pesticides- to water resources such as marine, freshwater, and under groundwater. Exposure to malathion through consumption of contaminated water may cause deleterious health effects on consumers. Determining the amount of pesticides used on farms can play an important role in preventing potential toxicity and pollution of nearby aquatic ecosystems. Therefore, this systematic review and meta-analysis is focused on evaluating the concentrations of Malathion in water resources while considering probabilistic health risk assessment. The international databases of Scopus, Embase, and PubMed were investigated to evaluate the related articles from January 01, 1968 to March 25, 2021. Thirty-four articles containing 206 samples from 15 countries were included. A meta-analysis of carcinogenic and non-carcinogenic risk assessments for Malathion was also performed. To determine uncertainty intervals, a Monte-Carlo simulation was conducted. The results of the meta-analysis showed that the rankings of Malathion pollution (from the most to the least) were: drinking water > surface waters > groundwaters. Moreover, the results of the risk assessments confirm that there is no non-carcinogenic risk for any of the study areas. The carcinogenic risk assessment was within the limit for the countries under this study, except for Ethiopia that was slightly over the limit as well as Iran, and Mexico had high carcinogenic risk.

Decontamination of toxic Malathion pesticide in aqueous solutions by Fenton-based processes: Degradation pathway, toxicity assessment and health risk assessment

This study evaluates the degradation efficiency of Malathion using Fenton (Fe²⁺/H₂O₂: F), photo-Fenton (UV/Fe²⁺/H₂O₂: PF), and sono-photo Fenton (US/UV/Fe²⁺/H₂O₂: SPF) processes as well as determines the toxicity of the byproducts of degradation. The effect of various operational parameters on the Malathion degradation rate, including pH, Fe²⁺ concentration, Malathion concentration, and H₂O₂ were studied. The removal efficiency was determined to be 98.79% for the SPF, > 70.92% for the PF, and > 55.94% for the F processes under the following optimal conditions: pH = 3, [H₂O₂]₀ = 700 mg/L, [Fe²⁺]₀ = 20 mg/L, and [Malathion]₀ = 20 mg/L. The operating costs (USD/kg_{Malathion-removed}) were acquired as SPF > PF > F. Moreover, Malaoxon, diethyl maleate, diethyl malate, ethyl 2-hydroxysuccinate, and D-malate were among the detected byproducts from the Malathion degradation in the SPF process. Both the non-carcinogenic risk and the carcinogenic risk were assessed to establish the quality of the effluent from all three processes. The toxicity of the treated effluents, determined by Vibrio fischeri luminescence, indicated that the toxicity depends on the selected treatment process. The high degradation efficiency of the Fenton-based processes is not equivalent to achieving detoxification of the effluents. As such, the SPF process was determined to be the most effective for the Malathion degradation, total organic carbon (TOC) removal, and health risk assessment.

Photocatalytic degradation of Penicillin G in aqueous solutions: Kinetic, degradation pathway, and microbioassays assessment

The photocatalytic degradation of pharmaceutical micropollutants of Penicillin G (PG) was investigated in a photoreactor at a laboratory scale. The impact of type of catalyst, pH, and initial concentration of PG were studied. Maximum removal efficiency was obtained at pH = 6.8, [ZnO]₀ = 0.8 g L^-1, and [PG]₀ = 5 mg L^-1 and reaction time of 150 min. The addition of persulfate sodium (PPS) enhanced the efficiency of the photocatalytic reaction. The efficiency of photolysis process in the presence of PPS was significantly improved to 72.72% compared to the classical photocatalysis system (56.71%). Optimum concentration of PPS to completely degraded PG was found to be 500 mg L^-1. The QuEChERS extraction, GC-MS/MS method, and concentration technique showed favorable performance identification of the possible mechanism of PG degradation pathway. Toxicity of PG and its by-products were evaluated using microbioassays assessment based on nine selected bacterial strains. Results confirmed the effectiveness of the implemented system and its safe use via the bacteria Bacillus subtilis, which has illustrated significant activity. Due to the high efficiency, facility benefits, and low-cost of the suggested process, the process can be considered for the degradation of various pharmaceutical contaminants in pharmaceutical industry treatment under the optimal conditions.

A comprehensive review on MXenes as new nanomaterials for degradation of hazardous pollutants: Deployment as heterogeneous sonocatalysis

MXene-based nanomaterials (MBNs) are two-dimensional materials that exhibit a series of sought after properties, including rich surface chemistry, adjustable bandgap structures, high electrical conductivity, hydrophobicity, thermal stability, and large specific surface area. MBNs have an exemplar performance when applied for the degradation of hazardous pollutants with various advanced oxidation processes such as heterogeneous sonocatalysis. As such, this work focuses on the sonocatalytic degradation of various hazardous pollutants using MXene-based catalysts. First, the general principles of sonocatalysis are examined, followed by an analysis of the main components of the MXene-based sonocatalysts and their application for pollutant degradation. Lastly, ongoing challenges are highlighted with recommendations to address the issues.

Optimization of thermostable proteases production under agro-wastes solid-state fermentation by a new thermophilic Mycothermus thermophilus isolated from a hydrothermal spring Hammam Debagh, Algeria

The present work investigates for the first time the presence and isolation of the thermophilic fungi from hydrothermal spring situated at the locality of Guelma, in the Northeast of Algeria. The production of the thermostable proteases and the optimization of culture conditions under agro-wastes solid-state fermentation to achieve optimal production capacity were explored. A statistical experimental approach consisting of two designs was used to determine the optimum culture conditions and to attain the greatest enzyme production. Besides, different agricultural wastes were initially evaluated as a substrate, whereby wheat bran was selected for enzyme production by the isolate under solid-state conditions. The isolate thermophilic fungi were identified as Mycothermus thermophilus by sequencing the ITS region of the rDNA (NCBI Accession No: MK770356.1). Among the various screened variables: the temperature, the inoculum size, and the moisture were proved to have the most significant effects on protease activity. Employing two-level fractional Plackett-Burman and a Box-Behnken designs statistical approach helped in identifying optimum values of screened factors and their interactions. The analysis showed up 6.17-fold improvement in the production of proteases (~1187.03 U/mL) was achieved under the optimal conditions of moisture content 47%, inoculum 5 × 10⁵ spores/g, and temperature at 42 °C. These significant findings highlight the importance of the statistical design in isolation of Mycothermus thermophilus species from a specific location as well as identifying the optimal culture conditions for maximum yield.

Graphene-based materials for metronidazole degradation: A comprehensive review

Due to its cytotoxic effect, metronidazole (MNZ) is a drug commonly used to treat bacterial, protozoal, and microaerophilic bacterial infections. After consumption, it undergoes a series of metamorphic reactions that lead to the degradation of oxidized, acetylated, and hydrolyzed metabolites in the environment. To eliminate such pollutants, due to their high potential, adsorption and photocatalysis extensive processes are used in which graphene can be used to improve efficiency. This review analyses the use of graphene as an absorbent and catalyst with a focus on absorption and photocatalytic degradation of MNZ by graphene-based materials (GBMs). The parameters affecting the adsorption, and photocatalytic degradation of MNZ are investigated and discussed. Besides, the basic mechanisms occurring in these processes are summarized and analyzed. This work provides a theoretical framework that can direct future research in the field of MNZ removal from aqueous solutions.

The concentration of persistent organic pollutants in water resources: A global systematic review, meta-analysis and probabilistic risk assessment

The persistent organic pollutants (POPs) are environmentally stable and highly toxic chemicals that accumulate in living adipose tissue and have a very destructive effect on aquatic ecosystems. To analyze the evolution of the concentration and prevalence of POPs such as α-HCH, β-HCH, γ-HCH, ∑-HCH, Heptachlor, Aldrin, p,p'-DDE, p,p'-DDT, ∑-DDT, and ∑-OCP in water resources, a search between January 01, 1970, to February 10, 2020, was followed using a systematic review and meta-analysis prevalence. Among the 2306 explored articles in the reconnaissance step, 311 articles with 5315 exemplars, 56 countries, and 4 types of water were included in the meta-analysis study. Among all studied POPs, the concentration of p,p'-DDT in water resources was the highest, especially in drinking water resources. The overall rank order based on the concentration and prevalence of POPs were surface water > drinking water > seawater > groundwater. To identify POPs-contaminated areas, the distance from the mean relative to their distribution was considered. The most to the least polluted areas included: South Africa, India, Turkey, Pakistan, Canada, Hong Kong, and China. The highest carcinogenic risk was observed for β-HCH (Turkey and China), followed by α-HCH (Mexico). The highest non-carcinogenic risk was identified for Aldrin (all analyzed countries), followed by Dieldrin (Turkey) and γ-HCH (Mexico). The Monte Carlo analysis (under the assumption that γ-HCH has a normal distribution), the mean obtained was 8.22E-07 for children and 3.83E-07 for adults. This is in accordance with the standard risk assessment approach. In terms of percentiles, the Monte-Carlo approach indicates that 75% of child population is under the 1.07E-06 risk and 95% of adults under 7.35E-06.

Endocrine disruptor chemicals. A review of their effects on male reproduction and antioxidants as a strategy to counter it

Endocrine disruptor chemicals are exogenous molecules that generate adverse effects on human health by destabilizing the homeostasis of endocrine system and affecting directly human reproductive system by inhibiting or activating oestrogenic or androgenic receptors. Endocrine disruptor chemicals generate transgenerational epigenetic problems, besides being associated with male infertility. Epidemiological data indicate that the increase in reproductive problems in males in the last 50 years is correlated with the increase of endocrine disrupting chemicals in the environment, being associated with a decrease in semen quality and direct effects on spermatozoa, such as alterations in motility, viability and acrosomal reaction, due to the generation of oxidative stress, and have also been postulated as a possible cause of testicular dysgenesis syndrome. Diverse antioxidants, such as C and E vitamins, N-acetylcysteine, selenium and natural vegetable extracts, are among the alternatives under study to counter the effects of endocrine disruptor chemicals. In some cases, the usage of them has given positive results and the opposite in others. In this review, we summarize the recent information about the effects of endocrine disruptor chemicals on male reproduction, on sperm cells, and the results of studies that have tested antioxidants as a strategy to diminish their harmful effects.

The Fenton-like reaction for Arsenic removal from groundwater: Health risk assessment

In this paper, the heterogeneous Fenton like-reaction for Arsenic-contaminated groundwater remediation based on the performance of FeSO₄ as an efficient and green catalyst and CaO₂ as a source of H₂O₂ was investigated. To intensify the heterogeneous Fenton process, three oxidants were tested: sodium percarbonate (SPC), sodium persulfate (SPS), and calcium peroxide (CP). The results showed that CP and SPC had a synergetic effect on the rate of Arsenic degradation, while SPS had an antagonistic effect. On the other hand, inorganic ions such as Na⁺, Mg²⁺ have a very low impact on the Arsenic removal efficiency, while the anions Cl^- and NO₃^- exhibited significant inhibition of Arsenic degradation. This effect may be imputed to the reaction and conversion of hydroxyl (HO^•) radicals to less reactive. Thus, HCO₃^- and humic acid dramatically raised the degradation rate. Also, the response Surface method based on Box-Behnken design was applied to examine the suitable modeling, and optimized condition of the Fenton like-reaction process, the maximum Arsenic removal efficiency of 94.91% is obtained when [Fe³⁺]₀ = 1.97 mM, [CaO₂]₀ = 1.74 mM and initial pH = 4.67. The obtained results showed that the Fenton-like reaction is an effective and reliable process for arsenic removal from groundwater with low non-carcinogenic risk (HQ) and carcinogenic risk (CR) values.

Application of chitosan-alginate bio composite for adsorption of malathion from wastewater: Characterization and response surface methodology

Agricultural effluents in aqueous media have caused serious threats due to adversely affect human health and the ecosystem. In this study, the low-cost easily accessible chitosan-alginate adsorbent was prepared for the removal of malathion from agricultural effluents using microemulsion method. The adsorbent was characterized using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The optimum experimental conditions, including adsorbent dosage (0.05-0.25 g), contact time (5-25 min), and concentration of malathion (5-25 mg L^-1) at five levels were studied using the composite central design (CCD) based on the response surface methodology (RSM). The highest removal percentage was obtained 82.35 with an adsorbent dosage of 0.18 g, contact time of 20 min, and initial concentration of 10 mg L^-1. The analysis of variance (ANOVA) was applied to assess the significance and adequacy of the model. The results revealed that quadratic model was proper for the prediction removal of malathion. The adsorption kinetics and isotherms were examined under optimal conditions. The Langmuir with a coefficient of determination (R²) = 0.99 and pseudo-second-order with R² = 0.99 were achieved as the best isotherm and kinetic models, respectively. The results showed that the chitosan-alginate biopolymer can be effective and affordable adsorbent for the removal of malathion from aqueous solution.

Study on influence factors of treating landfill leachate by ultraviolet-activated persulfate system

In recent years, there have been many studies on treating pollutants with ultraviolet-activated persulfate (UV/PDS) system. In this paper, the biochemical treatment effluent of landfill leachate from garbage incineration power plant was treated. The effect of treating landfill leachate with UV/PDS system in the low-pressure external device and medium-pressure built-in device was compared; it was concluded that in the latter device, the photon quantity increased, the energy loss decreased, and the probability of generating free radicals in the reaction between photons and S₂O₈^2- increased, which result the treatment efficiency of this system was higher. In addition, the leachate was treated by combining the activation method of spinel composite (CuO-MgAl₂O₄) with UV activation method, called CuO-MgAl₂O₄/UV/PDS. The experimental data showed that the processing effect of segmented dosing PDS process was higher than that of one-time addition process. Under the same conditions, the removal rates of CODcr were 83.10% and 19.76%, respectively. One of the reasons for this result may be that excessive PDS in CuO-MgAl₂O₄/PDS system of the latter process inhibited the treatment effect. This paper analyzes the efficiency of UV/PDS system, as well as CuO-MgAl₂O₄/UV/PDS combination process which were used to treat landfill leachate under different conditions; the results showed that the medium-pressure built-in device and segmented-dosing process could get better treatment effect.

Valorization and optimization of agro-industrial orange waste for the production of enzyme by halophilic Streptomyces sp

This study underlines the biotechnical valorization of the accumulated and unusable remains of agro-industrial orange fruit peel waste to produce α-amylase under submerged conditions by Streptomyces sp. KP314280 (20r). The response surface methodology based on central composite design (RSM-CCD) and artificial neural network coupled with a genetic algorithm (ANN-GA) were used to model and optimize the conditions for the α-amylase production. Four independent variables were evaluated for α-amylase activity including substrate concentration, inoculum size, sodium chloride powder (NaCl), and pH. A ten-fold cross-validation indicated that the ANN has a greater ability than the RSM to predict the α-amylase activity (R²_ANN = 0.884 and R²_RSM = 0.725). The analysis of variance indicated that the aforementioned four factors significantly affected the α-amylase activity. Additionally, the α-amylase production experiments were conducted according to the optimal conditions generated by the GA. The results indicated that the amylase yield increased by 4-fold. Moreover, the α-amylase production (12.19 U/mL) in the optimized medium was compatible with the predicted conditions outlined by the ANN-GA model (12.62 U/mL). As such, the ANN and GA combination is optimizable for α-amylase production and exhibits an accurate prediction which provides an alternative to other biological applications.

Cu2O/Fe3O4/MIL-101(Fe) nanocomposite as a highly efficient and recyclable visible-light-driven catalyst for degradation of ciprofloxacin

Nowadays, the widespread production and use of antibiotics have increased their presence in wastewater systems, posing a potential threat to the environment and human health. The development of advanced materials for treating antibiotics in wastewater has always received special attention. This study aimed to synthesize a novel Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposite and use it to degrade ciprofloxacin (CIP) antibiotics in an aqueous solution under visible light irradiation. The optical, structural, and morphological attributes of the developed nanocomposite were analyzed by XRD, FTIR, FE-SEM, TGA, DRS, BET, VSM, and UV-Vis techniques. Optimum circumstances for CIP photocatalytic degradation were acquired in 0.5 g L^-1 of catalyst dosage, pH of 7, and CIP concentration of 20 mg L^-1. The degradation efficiency was achieved 99.2% after 105 min of irradiation in optimum circumstances. The chemical trapping experiments confirmed that hydroxyl and superoxide radicals significantly contributed to the CIP degradation process. The results of this study indicated that Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposite was a highly stable photocatalyst that could effectively remove antibiotics from aqueous solutions. The CIP degradation efficiency only decreased by 6% after five cycles, indicating the excellent recyclability of Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposites.

Optimal degradation of organophosphorus pesticide at low levels in water using fenton and photo-fenton processes and identification of by-products by GC-MS/MS

This study aiming to determine the optimal conditions to degrade an organophosphate pesticide diazinon (DZN) at low levels concentrations (μg.mL^-1) and to identify the by-products generated. The degradation processes utilized were the Fenton and photo-Fenton. The iron concentration [Fe²⁺], the hydrogen peroxide concentrations [H₂O₂], and the solution pH are the investigated parameters. The Doehlert three-parameter experimental design was applied to model and optimize both degradation processes. The mathematical models suggested were assessed and validated by application of analysis of variances ANOVA. In the case of Fenton process, the greatest yield of degradation (79%) was obtained at [Fe²⁺] = 35 mg.L^-1 (0.63 mmol.L^-1), [H₂O₂] = 423 mg.L^-1 (12.44 mmol.L^-1), and pH = 5.0. In photo-Fenton process, the maximum yield of degradation (96%) was obtained under the conditions of [Fe²⁺] = 29 mg.L^-1 (0.52 mmol.L^-1), [H₂O₂] = 258 mg.L^-1 (7.59 mmol.L^-1) and pH = 4.6. QuEChERS (quick, easy, cheap, effective, rugged, and safe), as extraction technique, and GC-MS/MS (gas chromatography coupled with triple quadrupole mass spectrometry) were used to identify the by-products degradation of DZN. The identified compounds are diazoxon, triethyl phosphate, triethyl thiophosphate, 2-isopropyl-5-ethyl-6-methylpyrimidine-4-ol, 2-isopropyl-6-methylpyrimidine-4-ol (IMP) and hydroxydiazinon. Three possible pathways for diazinon degradation have been suggested and the hydroxylation, oxidation and hydrolysis are likely probable degradation mechanisms.

Towards a comprehensive understanding of malathion degradation: theoretical investigation of degradation pathways and related kinetics under alkaline conditions

Malathion is a commercially available insecticide that functions by acting as an acetylcholinesterase inhibitor. Of more significant concern, if left in the environment, some of the products observed from the degradation of malathion can function as more potent toxins than the parent compound. These compounds may threaten human life if they are present in high quantities during operation in contaminated or industrial areas. Several experimental studies have been performed to elucidate the possible degradation products of malathion under various conditions to probe both the application of potential remediation methods and the environmental fate of the degradation products. However, only limited computational studies have been reported to delineate the mechanism by which malathion degrades under environmental conditions and how these degradation mechanisms are intertwined with one another. Herein, M06-2X DFT computations were employed to develop comprehensive degradation pathways from the parent malathion compound to a multitude of experimentally observed degradation products. These data corroborate experimental observations that multiple degradation pathways (ester hydrolysis and elimination) are in competition with each other, and the end-products can therefore be influenced by environmental factors such as temperature. Furthermore, the products resulting from any of the initial degradation pathways (ester hydrolysis, elimination, or P-S hydrolysis) can continue to degrade under the same conditions into compounds that are also reported to be toxic.

Electrocatalytic degradation of diuron herbicide using three-dimensional carbon felt/β-PbO2 anode as a highly porous electrode: Influencing factors and degradation mechanisms

Traditional planar PbO₂ anodes have been used extensively for the electrocatalytic degradation process. However, by using porous PbO₂ anodes that have a three-dimensional architecture, the efficiency of the process can be significantly upgraded. In the current study, carbon felt (CF) with a highly porous structure and a conventional planar graphite sheet (G) were used as electrode substrate for PbO₂ anodes. Both CF/β-PbO₂ and G/β-PbO₂ anodes were prepared by the anodic deposition method. The main properties of the electrodes were characterized by XRD, EDX-mapping, FESEM, and BET-BJH techniques. The electrocatalytic degradation of diuron using three-dimensional porous CF/β-PbO₂ anode was modeled and optimized by a rotatable central composite design. After optimizing the process, the ability of porous CF/β-PbO₂ and planar G/β-PbO₂ anodes to degrade and mineralize diuron was compared. The electrocatalytic degradation of the diuron was well described by a quadratic model (R² > 0.99). Under optimal conditions, the kinetics of diuron removal using CF/β-PbO₂ anode was 3 times faster than the G/β-PbO₂ anode. The energy consumed for the complete mineralization of diuron using CF/β-PbO₂ anode was 2077 kWh kg^-1 TOC. However, the G/β-PbO₂ anode removed only 65% of the TOC by consuming 54% more energy. The CF/β-PbO₂ had more stability (115 vs. 91 h), larger surface area (1.6287 vs. 0.8565 m² g^-1), and higher oxygen evolution potential (1.89 vs. 1.84 V) compared to the G/β-PbO₂. In the proposed pathways for diuron degradation, the aromatic ring and groups of carbonyl, dimethyl urea, and amide were the main targets for HO^• radical attacks.

Artificial Neural Networks for Predicting Hydrogen Production in Catalytic Dry Reforming: A Systematic Review

Dry reforming of hydrocarbons, alcohols, and biological compounds is one of the most promising and effective avenues to increase hydrogen (H2) production. Catalytic dry reforming is used to facilitate the reforming process. The most popular catalysts for dry reforming are Ni-based catalysts. Due to their inactivation at high temperatures, these catalysts need to use metal supports, which have received special attention from researchers in recent years. Due to the existence of a wide range of metal supports and the need for accurate detection of higher H2 production, in this study, a systematic review and meta-analysis using ANNs were conducted to assess the hydrogen production by various catalysts in the dry reforming process. The Scopus, Embase, and Web of Science databases were investigated to retrieve the related articles from 1 January 2000 until 20 January 2021. Forty-seven articles containing 100 studies were included. To determine optimal models for three target factors (hydrocarbon conversion, hydrogen yield, and stability test time), artificial neural networks (ANNs) combined with differential evolution (DE) were applied. The best models obtained had an average relative error for the testing data of 0.52% for conversion, 3.36% for stability, and 0.03% for yield. These small differences between experimental results and predictions indicate a good generalization capability.

Data mining for pesticide decontamination using heterogeneous photocatalytic processes

Pesticides are chemical compounds used to kill pests and weeds. Due to their nature, pesticides are potentially toxic to many organisms, including humans. Among the various methods used to decontaminate pesticides from the environment, the heterogeneous photocatalytic process is one of the most effective approaches. This study focuses on artificial intelligence (AI) techniques used to generate optimum predictive models for pesticide decontamination processes using heterogeneous photocatalytic processes. In the present study, 537 valid cases from 45 articles from January 2000 to April 2020 were filtered based on their content collected and analyzed. Based on cross-industry standard process (CRISP) methodology, a set of four classifiers were applied: Decision Trees (DT), Bayesian Network (BN), Support Vector Machines (SVM), and Feed Forward Multilayer Perceptron Neural Networks (MLP). To compare the accuracy of the selected algorithms, accuracy, and sensitivity criteria were applied. After the final analysis, the DT classification algorithm with seven factors of prediction, the accuracy of 91.06%, and sensitivity of 80.32% was selected as the optimal predictor model.

A global systematic review, meta-analysis and health risk assessment on the quantity of Malathion, Diazinon and Chlorpyrifos in Vegetables

It is widely believed that an increasing trend in the production and consumption of vegetables has led to a dramatic rise in the use of pesticides potentially threatening the health of consumers around the world. This systematic study along with meta-analysis has mainly centered on the evaluation of the quantity of three well-known pesticides namely, Malathion (MLT), Diazinon (DZN) and Chlorpyrifos (CPF) in vegetables. In this regard, a comprehensive literature search has been performed over the last decade (January 1, 2011 to June 21, 2020) within the scientific databases including PubMed, Web of Science, and Scopus. Of 1239 articles identified through the database screening, 22 plus 37 data report were retained and included in the meta-analysis phase. Additionally, the probabilistic human health risks for the consumers due to the intake of CPF, DZN and MLT from eating vegetables were estimated by the Monte Carlo Simulated (MCS) method. According to the findings, the maximum quantities of MLT, DZN and CPF in the vegetables were observed in Pakistan (222 μg/kg, 95%CI = 214.94-229.08), Thailand (245.00, 95% CI = 235.2-254.8) and South Korea (440 μg/kg, 95% CI = 437.19-442.81), while the lowest concentration levels were reported in China (1.7 μg/kg, 95% CI = 1.56-1.84), Poland (0.57, 95% CI = 0.46-0.68) and Poland (5.78 μg/kg, 95% CI = 4.40-7.12), respectively. The results of the Egger's and the Begg's tests revealed that no bias with regard to the potential publication was observed. Finally, non-carcinogenic risk assessment results demonstrated that the exposure to the studied pesticides thorough vegetables consumption could not threaten the health of consumers.

Degradation of malathion in the solution of acetyl peroxyborate activated by carbonate: Products, kinetics and mechanism

The degradation process of malathion in the acetyl peroxyborate (APB) solution of different APB/malathion molar ratio and in the carbonate-activated APB (APB/CO₃^2-) solution of different pH was studied by ³¹P NMR technology. In the APB solution, all malathion could be degraded in 47.5 min when the molar ratio of APB/malathion was 60. CO₃^2- could effectively activate APB to degrade all malathion in 10 min at pH of 10 when APB/malathion was 10, which was obviously higher than in APB solution. ¹O₂, •O₂^-, •OH and carbon-centered radicals (RC•) could be produced in the APB/CO₃^2- solution, and the degradation of malathion was mainly affected by RC•. The degradation mechanism of malathion in the APB/CO₃^2- solution was proposed based on the research results of malathion degradation process by ³¹P NMR and active species quenching test, which involves two steps: the first step is the oxidation of malathion to malaoxon by RC•, and the second step is the hydrolysis of malaoxon to dimethyl phosphate via hydroxyl anions nucleophilic addition.

Photocatalytic-persulfate- oxidation for diclofenac removal from aqueous solutions: Modeling, optimization and biotoxicity test assessment

In this paper, the influence of several aquatic factors (the nature of catalyst, the initial pH and the initial concentration of the pollutant) on the photocatalytic degradation of diclofenac (DFC), one of the most widely prescribed anti-inflammatory non-steroidal drug, was studied. Also, in order to examine the intensification process, the variation of the photocatalytic DFC degradation in the presence of sodium persulfate (PPS) was analyzed. It was found that, compared to titanium dioxide (TiO₂), the zinc oxide (ZnO) photocatalyst performed exceptionally well, with a 96.13% DFC degradation efficiency after 150 min. The photodegradation of DFC by ZnO catalyst fitted well the Langmuir-Hinshelwood kinetic model. The maximum efficiency is 97.27% for simulated solar-UVA/ZnO/PPS and 77% for simulated solar-UVA/ZnO. In order to determine the optimal conditions leading to the maximization of DFC removal, an artificial neural network (ANN) modeling approach combined with genetic algorithm (GA) was applied. The best ANN determined had a correlation of 0.999 and it was further used in the process optimization where a 99.7% degradation efficiency was identified as the optimum under the following conditions: DFC initial concentration 37,9 mg L^-1, pH 5,88 and PPS initial concentration 500 mg L^-1. The effectiveness of the process and the toxicity of the pharmaceutical pollutants and their by-products were also evaluated and confirmed by the biological tests using liver and kidney of Mus musculus mice.

Simultaneous multi-determination of pesticide residues in black tea leaves and infusion: a risk assessment study

This study aimed to investigate the concentration of 33 pesticide residues in 60 black tea samples collected from Iran, determine their transfer rate, and assess their health risk during brewing. Pesticide extraction and analysis were performed by using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and gas chromatography/tandem mass spectrometry (GC-MS/MS), respectively. The limits of detection (LOD) and the limits of quantification (LOQ) of pesticides were ranged 0.1-7.26 and 0.8-24 μg/kg for dried tea leaves and 0.03-3.1 and 0.09-10 μg/L for the tea infusion, respectively. The levels of pesticide residue in 52 (86.67%) out of 60 tea samples were above the LOD (0.1-7.26 μg/kg). Twenty four (40%) of the samples contained pesticides in a concentration higher than the maximum residue limit (MRL) set by the European Commission (EC). Seven out of 33 validated pesticides were detected in dried tea leaf samples that only four of seven, including buprofezin, chlorpyrifos, hexaconazole, and triflumizole, were transferred into tea infusion, demonstrating that the concentrations of pesticides in infusion were raised during brewing. The risk assessment study for detected pesticides in the tea infusion samples indicated that this beverage consumption was safe for consumers, while the mean residue of some pesticides in positive samples was higher than the MRL; therefore, periodic control of these pesticides should be regularly implemented.

NiP/CuO composites: Electroless plating synthesis, antibiotic photodegradation and antibacterial properties

This work reports a simple method to prepare nickel-phosphorus (Ni-P) alloy modified CuO (Ni-P/CuO) composite, which shows excellent performance in terms of photodegradation antibiotics, particularly regarding the antibacterial properties. The Ni-P/CuO composites were prepared via two steps. The first step was to produce CuO by the hydrothermal method and the second step was to grow Ni-P in-situ on the surface of CuO through electroless plating. After loading of Ni-P, the photocatalytic activity of CuO for the decomposition of antibiotics is significantly increased under visible light irradiation. The photocatalytic activity of Ni-P/CuO with 4 wt% Ni-P loading is 25 times higher than that of CuO. Compared with CuO, the antibacterial activity of Ni-P/CuO with 4 wt% Ni-P loading against Escherichia coli is strongly increased. Based on the photoluminescence and photocurrent measurements of CuO and Ni-P/CuO, Ni-P cocatalyst improves the separation and transfer of the photogenerated charge in CuO, and enhances the photocatalytic activity of antibacterial performance. This work reveals that using Ni-P as the cocatalyst can strengthen the photocatalytic performance of CuO, which has great application potential in water purification and antibacterial treatments.

Cold plasma for mitigating agrochemical and pesticide residue in food and water: Similarities with ozone and ultraviolet technologies

Pesticide and agrochemical residues in food and water are among hazardous chemicals that are associated with adverse health effects. Consequently, technologies for pesticide abatement in food and water remain in focus. Cold plasma is an emerging decontamination technology, that is being increasingly explored for the abatement of agrochemical and pesticide residue in food and water. In some cases, rapid and complete degradation of pesticide residues has come to light. Such promising results encourage exploring scale-up and commercialization. To achieve this, unraveling mechanisms involved in plasma decontamination and the nature of degradation products is needed. The present review identifies the mechanisms involved in plasma- assisted removal of pesticide residues from food and water, draws parallels with mechanism of ozone and ultraviolet technologies, investigates the chemistry of the intermediates and degradates, and identifies some future research needs. The review recognizes that mechanisms involved in plasma processes have overlapping similarities to those identified for ozone and ultraviolet light, involving oxidation by hydroxyl radical and photo-oxidation. The toxicity of intermediates and degradates in plasma processing have not received much attention. The safety aspects of end products form plasma led degradation of pesticides should be considered for practical exploitation. Identification of intermediates and degradation products, recognition of most potent plasma species, understanding the influence of co-existing entities, the energy efficiency of plasma reactors, and the process economics deserve research focus.