Degradation of emerging contaminants by sono-Fenton process with in situ generated H2O2 and the improvement by P25-mediated visible light irradiation

Origin, types, and contribution of emerging pollutants to environmental degradation and their remediation by physical and chemical techniques

The growing presence of emerging pollutants (EPs) in aquatic environments, as well as their harmful impacts on the biosphere and humans, has become a global concern. Recent developments and advancements in pharmaceuticals, agricultural practices, industrial activities, and human personal care substances have paved the way for drastic changes in EP concentrations and impacts on the ecosystem. As a result, it is critical to mitigate EP's harmful effects before they jeopardize the ecological equilibrium of the overall ecosystem and the sustainable existence of life on Earth. This review comprehensively documented the types, origins, and remediation strategies of EPs, and underscored the significance of this study in the current context. We briefly stated the major classification of EPs based on their organic and inorganic nature. Furthermore, this review systematically evaluates the occurrence of EPs due to the fast-changing ecological scenarios and their impact on human health. Recent studies have critically discussed the emerging physical and chemical processes for EP removal, highlighting the limitations of conventional remediation technologies. We reviewed and presented the challenges associated with EP remediation and degradation using several methods, including physical and chemical methods, with the application of recent technologies. The EP types and various methods discussed in this review help the researchers understand the nature of present-day EPs and utilize an efficient method of choice for EP removal and management in the future for sustainable life and development activities on the planet.

Intelligent multifunctional ruthenium monoatomic/ZnAl-LDH photocatalysts for simultaneous detection and rapid degradation of antibiotics

The construction and precise synthesis of materials based on functional and structural orientations have emerged as a pivotal platform in the field of environmental management. In this paper, an efficient and stable catalyst (RuLDH) was constructed to achieve this goal. RuLDH comprises individual Ru atoms that are uniformly dispersed on ZnAl-LDH, achieved by room temperature stirring. Remarkably, RuLDH exhibits exceptional performance under visible light, effectively triggering the photocatalytic degradation of tetracycline hydrochloride (TC) via peroxymonosulfate (PMS) with a remarkable efficiency of 100%, all while avoiding the generation of highly toxic intermediates. In addition, RuLDH0.2 demonstrated its utility in fluorescence detection of TC, showcasing commendable analytical performance characterized by rapid response, low detection limit, and robust resistance to environmental interferences (with a detection limit of 1.0 mg/L). Notably, the RuLDH0.2/PMS/Vis system exhibited remarkable efficacy in treating actual pesticide wastewater, effectively exerting bactericidal and disinfectant effects. This study serves as a source of inspiration for the design of multifunctional single-atom catalysts, thereby pushing the boundaries of "integration of diagnosis and treatment" in environmental management and control.

Electrochemical-based approaches for the treatment of pharmaceuticals and personal care products in wastewater

In recent times, emerging contaminants (ECs) like pharmaceuticals and personal care products (PPCPs) in water and wastewater have become a major concern in the environment. Electrochemical treatment technologies proved to be more efficient to degrade or remove PPCPs present in the wastewater. Electrochemical treatment technologies have been the subject of intense research for the past few years. Attention has been given to electro-oxidation and electro-coagulation by industries and researchers, indicating their potential to remediate PPCPs and mineralization of organic and inorganic contaminants present in wastewater. However, difficulties arise in the successful operation of scaled-up systems. Hence, researchers have identified the need to integrate electrochemical technology with other treatment technologies, particularly advanced oxidation processes (AOPs). Integration of technologies addresses the limitation of indiviual technologies. The major drawbacks like formation of undesired or toxic intermediates, s, energy expenses, and process efficacy influenced by the type of wastewater etc., can be reduced in the combined processes. The review discusses the integration of electrochemical technology with various AOPs, like photo-Fenton, ozonation, UV/H2O2, O3/UV/H2O2, etc., as an efficient way to generate powerful radicals and augment the degradation of organic and inorganic pollutants. The processes are targeted for PPCPs such as ibuprofen, paracetamol, polyparaben and carbamezapine. The discussion concerns itself with the various advantages/disadvantages, reaction mechanisms, factors involved, and cost estimation of the individual and integrated technologies. The synergistic effect of the integrated technology is discussed in detail and remarks concerning the prospects subject to the investigation are also stated.

Systematic study of the synergistic and kinetics effects on the removal of contaminants of emerging concern from water by ultrasound in the presence of diverse oxidants

The enhancement of the ultrasound system by adding diverse oxidants to remove a model contaminant (acetaminophen, ACE) in water was investigated. Different parameters were evaluated to study their effect on both the degradation kinetics and the synergy of the combination. The variables studied were the ultrasonic frequency (575, 858, and 1135 kHz), type of oxidant (hydrogen peroxide, sodium peroxydisulfate (or persulfate, PDS), and potassium peroxymonosulfate (PMS)), ACE concentration (4, 8, and 40 µM), and oxidant concentration (0.01, 0.1, 1, and 5 mM). Particular interest was placed on synergistic effects, implying that one process (or both) is activated by the other to lead to greater efficiency. Interestingly, the parameters that led to the higher synergistic effects did not always lead to the most favorable degradation kinetics. An increase in ACE removal of 20% was obtained using the highest frequency studied (1135 kHz), PMS 0.1 mM, and the highest concentration of ACE (40 µM). The intensification of degradation was mainly due to the ability of ultrasound to activate oxidants and produce extra hydroxyl radicals (HO•) or sulfate radicals (SO4•-). Under these conditions, treatment of ACE spiked into seawater, hospital wastewater, and urine was performed. The hospital wastewater matrix inhibited ACE degradation slightly, while the urine components inhibited the pollutant degradation completely. The inhibition was mainly attributed to the competing organic matter in the effluents for the sono-generated radical species. On the contrary, the removal of ACE in seawater was significantly intensified due to "salting out" effects and the production of the strong oxidant HOCl from the reaction of chloride ions with PMS.

Effects of gas saturation and sparging on sonochemical oxidation activity under different liquid level and volume conditions in 300-kHz sonoreactors: Zeroth- and first-order reaction comparison using KI dosimetry and BPA degradation

The sonochemical oxidation activity was investigated for gas saturation and gas sparging under various liquid levels and volumes in 300 kHz sonoreactors. The liquid levels and volumes ranged from 5λ (25 mm, 0.47 L) to 50λ (250 mm, 4.30 L) and two gas mixtures, Ar:O₂ (75:25) and N₂:O₂ (75:25), were used. Two types of reaction kinetics were observed to quantitatively analyze the sonochemical oxidation reactions: zero-order (KI dosimetry: C₀ = 60.2 mM) and first-order (Bisphenol A (BPA) degradation: C₀ = 0.043 mM). The masses of the sonochemical oxidation reactions were calculated and compared rather than the concentrations to more accurately compare the sonochemical oxidation activity under different liquid volume conditions. First, as the liquid level or volume increased for the zero-order reactions, the concentration of I₃^- ions representing the volume-averaged activity decreased substantially for gas saturation owing to the increase in liquid volume. However, gas sparging substantially enhanced sonochemical oxidation activity, and the mass of I₃^- ions representing the total activity remained constant as the liquid level increased from 20λ because of the improved liquid mixing and a shift in the sonochemical active zone. Second, as evidenced by the zero-order reactions, the concentration of BPA decreased considerably as the liquid level or volume increased in the first-order reactions. When gas sparging was used, higher reaction constants were obtained for both gas mixtures, ranging from 40λ to 50λ. However, a comparison of the sonochemical oxidation activity in terms of the degraded mass of BPA was inapplicable as the concentration of BPA decreased substantially and a lack of reactants occurred for the lower liquid level and volume conditions as the irradiation time elapsed. Instead, using the first-order reaction constant, a comparison of the required reaction times for a specific removal efficiency (30%, 60%, and 90%) was proposed. Gas sparging can substantially reduce the reaction time required for a liquid level of 40λ or higher.

Mechanism analysis of hydroxypropyl guar gum degradation in fracture flowback fluid by homogeneous sono-Fenton process

An effective hybrid system was applied as the first report for the successful treatment of key pollutants (hydroxypropyl guar gum, HPG) in fracturing flowback fluid, and the synergistic index of the hybrid system was 20.45. In this regard, chemical oxygen demand (COD) removal ratio was evaluated with various influencing operating factors including reaction time, H₂O₂ concentration, Fe²⁺ concentration, ultrasonic power, initial pH, and temperature. The optimal operating parameters by single-factor analysis method were: the pH of 3.0, the H₂O₂ concentration of 80 mM, the Fe²⁺ concentration of 5 mM, the ultrasonic power of 180 W, the ultrasonic frequency of 20-25 kHz, the temperature of 39 ℃, the reaction time of 30 min, and the COD removal rate reached 81.15 %, which was permissible to discharge surface water sources based on the environmental standards. A possible mechanism for HPG degradation and the generation of reactive species was proposed. Results of quenching tests showed that various impacts of the decomposition rate by addition of scavengers had followed the order of EDTA-2Na < BQ < t-BuOH, therefore OH radicals had a dominant role in destructing the HPG. Based on the kinetic study, it was concluded that Chan Kinetic Model was more appropriate to describe the degradation of HPG. Identification of intermediates by GC-MS showed that a wide range of recalcitrant compounds was removed and/or degraded into small molecular compounds effectively after treatment. Under the optimal conditions, the sono-Fenton system was used to treat the fracturing flowback fluid with the initial COD value of 675.21 mg/L, and the COD value decreased to 80.83 mg/L after 60 min treatment, which was in line with the marine sewage discharge standard. In conclusion, sono-Fenton system can be introduced as a successful advanced treatment process for the efficient remediation of fracture flowback fluid.

Statistical modeling optimization for antibiotics decomposition by ultrasound/electro-Fenton integrated process: Non-carcinogenic risk assessment of drinking water

The present work proposes an ultrasound (US) assisted electro-Fenton (EF) process for eliminating penicillin G (PNG) and ciprofloxacin (CIP) from aqueous solutions and the process was further optimized by response surface methodology (RSM)- Box-Behnken design (BBD). The impact of pH, hydrogen peroxide (H₂O₂) concentration, applied voltage, initial pollutant concentration, and operating time were studied. The capability application of the electro-Fenton (EF) and US processes was compared separately and in combination under the optimum conditions of pH of 4, a voltage of 15 V, the initial antibiotic concentration of 20.7 mg/L, H₂O₂ concentration of 0.8 mg/L, and the operating time of 75 min. The removal efficiency of PNG and CIP using the sono-electro-Fenton (SEF) process, as the results revealed, was approximately 96% and 98%, respectively. The experiments on two scavengers demonstrated that ^⦁OH contributes significantly to the CIP and PNG degradation by SEF, whereas ^⦁O^-₂ corresponds to only a negligible amount. The total organic carbon (TOC) and chemical oxygen demand (COD) analyses were used to assess the mineralization of CIP and PNG. The efficiency of COD and TOC removal was reached at 73.25% and 62.5% for CIP under optimized operating circumstances, and at 61.52% and 72% for PNG, respectively. These findings indicate that a sufficient rate of mineralization was obtained by SEF treatment for the mentioned pollutants. The reaction kinetics of CIP and PNG degradation by the SEF process were found to follow a pseudo-first-order kinetic model. In addition, the human health risk assessment of natural water containing CIP and PNG that was purified by US, EF, and SEF processes was done for the first time. According to the findings, the non-carcinogenic risk (HQ) caused by drinking purified water by all three systems was calculated in the acceptable range. Thus, SEF is a proper system to remove various antibiotics in potable water and reduces their human health risks.

One-pot synthesis of graphene hydrogel/M (M: Cu, Co, Ni) nanocomposites as cathodes for electrochemical removal of rifampicin from polluted water

Nowadays, the removal of pharmaceutical contaminants from water resources and wastewater is of great importance due to environmental and health issues. Over the decades, various methods have been reported to remove pollutants from wastewater. Among the developed methods, advanced oxidation processes (AOPs) have received significant attention from researchers. In this study, we report the one-pot synthesis of graphene hydrogel-metal (GH-M, M: Co, Ni, Cu) nanocomposites via the combination of polyol and hydrothermal methods. The structure of the resulting nanocomposites was examined by transmission electron microscopy (TEM), inductively coupled plasma-mass spectroscopy (ICP-MS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy methods. Afterward, as-prepared GH-Cu, GH-Co, and GH-Ni nanocomposites were used to prepare cathodes for the electro-Fenton (EF) process to remove rifampicin (RIF) from polluted water. The effect of operational parameters, including current density (mA/cm²), initial pH, initial RIF concentration (mg/L), and process time (min) was investigated via response surface methodology (RSM). The optimal values for current density, pH, initial RIF concentration, and process time using GH-Ni as cathode were 30 mA/cm², 5, 30 mg/L, and 90 min, respectively. The results at optimal values showed that the maximum RIF removal efficiency for GH-Cu, GH-Co, and GH-Ni cathodes was 90.47, 92.60, and 93.69%, respectively. Brunauer Emmett Teller (BET), atomic force microscopy (AFM), energy-dispersive X-ray (EDX), and cyclic voltammetry (CV) analyses were performed to investigate the performance of the cathodes for the RIF removal. Finally, total organic carbon (TOC), gas chromatography-mass spectrometry (GC-MS), and atomic absorption spectroscopy (AAS) analyses were performed for further investigation of the RIF removal from polluted water. The results claimed that one-pot synthesized GH-M cathodes can effectively remove RIF from polluted water through EF process.

Heterogeneous Advanced Oxidation Processes: Current Approaches for Wastewater Treatment

Nowadays, water pollution is one of the most dangerous environmental problems in the world. The presence of the so-called emerging pollutants in the different water bodies, impossible to eliminate through conventional biological and physical treatments used in wastewater treatment plants due to their persistent and recalcitrant nature, means that pollution continues growing throughout the world. The presence of these emerging pollutants involves serious risks to human and animal health for aquatic and terrestrial organisms. Therefore, in recent years, advanced oxidation processes (AOPs) have been postulated as a viable, innovative and efficient technology for the elimination of these types of compounds from water bodies. The oxidation/reduction reactions triggered in most of these processes require a suitable catalyst. The most recent research focuses on the use and development of different types of heterogeneous catalysts, which are capable of overcoming some of the operational limitations of homogeneous processes such as the generation of metallic sludge, difficult separation of treated water and narrow working pH. This review details the current advances in the field of heterogeneous AOPs, Fenton processes and photocatalysts for the removal of different types of emerging pollutants.

Revealing the enhancing mechanisms of Fe-Cu bimetallic catalysts for the Fenton-like degradation of phenol

To develop a heterogeneous Fenton-like catalyst with desirable activity and reusability remains a great challenge for the practical degradation of environmental remediation. Herein, we demonstrate a dendritic Fe-Cu bimetallic catalyst consisted of a Cu/Fe₃O₄ shell and a FeCu core (E100). In comparisons of single Cu, Fe and Fe₃O₄, E100 performs far better performance for the Fenton-like degradation of phenol, and its dominant Fenton-like active centers are Fe species under acidic pH or Cu species under neutral pH. Particularly, Cu-based Fenton-like reactions are greatly accelerated by galvanic micro-cells effects that come from the special co-existence of Cu/Fe₃O₄ shell, and subsequently, owing to the Cu leaching from the shell, the inner FeCu core of E100 is able to be exposed and further strengthen Fe-based Fenton-like reactions. Overall, the appropriate synergistic effects endow E100 with superior catalytic activity and reusability than other catalysts. Our work pushes forward a step for understanding the catalytic mechanism of Fe-Cu bimetallic catalysts and provides new sights for fabricating efficient Fenton-like catalysts for environmental remediation.

Modified Composite Based on Magnetite and Polyvinyl Alcohol: Synthesis, Characterization, and Degradation Studies of the Methyl Orange Dye from Synthetic Wastewater

The goal of the present paper was to synthesize, characterize, and evaluate the performance of the modified composite based on magnetite (Fe₃O₄) and polyvinyl alcohol (PVA). The obtained composite was used to degrade Methyl Orange dye from synthetic wastewater by a laboratory photocatalytic reactor. Various parameters of the photodegradation process were tested: composite dosage, amount of hydrogen peroxide (H₂O₂), and pH. The composite was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The degradation experiments indicated that the complete dye decolorization depended on the amount of H₂O₂. In addition, the H₂O₂ could accelerate Methyl Orange degradation to more highly oxidized intermediates in the presence of UV light (99.35%). The results suggested that the obtained modified composite could be used to treat wastewater containing various types of dyes.

Enhanced degradation of bisphenol A by mixed ZIF derived CoZn oxide encapsulated N-doped carbon via peroxymonosulfate activation: The importance of N doping amount

In this study, mixed metal cobalt zinc oxide embedded nitrogen enriched porous carbon composites (CoZnO-PC) were prepared via pyrolyzing polyvinylpyrrolidone (PVP) encapsulated Co, Zn-bimetal centered zeolitic imidazolate frameworks (ZIF). The prepared composites were then used to activate peroxymonosulfate (PMS) for bisphenol A (BPA) removal in water. When mole ratio of Co/Zn was 2/1, the resulted Co₂Zn₁O-PC possessed spinel structure with prominent degradation capability, in which the introduction of Zn accelerated the PMS activation performance of Co through establishing bimetal synergistic interactions. Both radical and non-radical activation pathways were existed in the Co₂Zn₁O-PC/PMS system, in which Co₂Zn₁O dominated the radical pathway whereas PC dominated the non-radical way. Since PVP contained abundant nitrogen atoms and could form strong coordination interactions with the ZIF precursor, the introduction of PVP in the ZIF precursor prevented pore collapsing during pyrolysis process, as well as enhancing the nitrogen content in the pyrolzed composites, which significantly promoted the generation of singlet oxygen. With combined pathways, the Co₂Zn₁O-PC/PMS system showed a wide pH application range with promising mineralization rate. Meanwhile, the spinel-structured Co₂Zn₁O-PC was magnetically separable with desirable recyclability. This study presents a novel composite with remarkable performance for the removal of refractory organic pollutants in municipal wastewater.

Biodegradation of sulfonamide antibiotics through the heterologous expression of laccases from bacteria and investigation of their potential degradation pathways

In this study, seven laccase genes from different bacteria were linked with the signal peptides PelB, Lpp or Ompa for heterologous expression in E. coli. The recombinant strains were applied for the removal of sulfadiazine (SDZ), sulfamethazine (SMZ), and sulfamethoxazole (SMX). The results obtained for different signal peptides did not provide insights into the removal mechanism. The removal ratios of SDZ, SMZ, and SMX obtained with the recombinant strain 6#P at 60 h were around 92.0%, 89.0%, and 88.0%, respectively. The degradation pathways of sulfonamides have been proposed, including SO₂ elimination, hydroxylation, oxidation, pyrimidine ring cleavage, and N-S bond cleavage. Different mediators participate in the degradation of antibiotics through different mechanisms, and different antibiotics have different responses to the same mediator. The addition of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) slightly promoted the removal of sulfonamides by most recombinant strains with different signal peptides, especially for the recombinant strain 2#O. The removal of sulfonamides by 1-hydroxybenzotriazole (HBT) varied with the recombinant strains. Syringaldehyde (SA) had a slight inhibitory effect on the removal of sulfonamides, with the most significant effect on strains 7#L and 7#O.

Fe3C-porous carbon derived from Fe2O3 loaded MOF-74(Zn) for the removal of high concentration BPA: The integrations of adsorptive/catalytic synergies and radical/non-radical mechanisms

In this study, novel Fe₃C-porous carbon composites (Fe₃C-C) were prepared via the pyrolysis of Fe₂O₃ loaded MOF-74(Zn), which could integrate both strong adsorption properties and excellent peroxymonosulfate (PMS) activating performance for the removal of bisphenol A (BPA) in water. Results indicated that the composite obtained at 1000 °C (Fe₃C-C1000) exhibited optimal catalytic capability. Specifically, 0.1 mM BPA could be completely removed by 0.1 g/L Fe₃C-C1000 within 10 min after the adsorption enrichment. Afterwards, the mechanism of Fe₃C-C/PMS system was unveiled based on quenching tests, electron spin resonance analysis, electrochemical analysis, PMS consumption detection and solvent exchange (H₂O to D₂O) test. The BPA degradation pathways were also analyzed through identifying its decomposition intermediates. Results showed that the Fe₃C and porous carbon constituents could activate PMS via radical and non-radical mechanisms respectively, and BPA was readily degraded through both pathways. Additionally, it was found that the Fe₃C-C1000/PMS system could maintain conspicuous catalytic performance in a variety of complicated water matrices with wide pH application range and long-time use stability. This study suggests a new insight for the design and development of novel catalyst which can be used for the removal of refractory organic contaminants with high concentrations in water media.

Electron beam irradiation of typical sulfonamide antibiotics in the aquatic environment: Kinetics, removal mechanisms, degradation products and toxicity assessment

Due to their widespread use and harmful effects on aquatic environment, sulfonamide antibiotics (SAs) have become an emerging pollutant of great concern around the world. In this study, we investigated the degradation process and mechanism of sulfamerazine (SMR), sulfadiazine (SDZ), and sulfapyridine (SPD) by electron-beam irradiation (EBI). The results showed that the three SAs were well suited to the pseudo-first-order reaction kinetics, and they could be almost completely removed with high efficiency (5 kGy). Among the environmental factors, pH (3.0) and O₂ atmosphere can further enhance the removal of the sulfonamides (SAs), while NO₂^- has the most pronounced degrading inhibitory effects among the many ions, these results illustrate that hydroxyl radicals play a dominant role. Compared with SMR and SDZ, the degree of mineralization of lower molecular weight SPD is obvious (45%). LC-MS and DFT calculations indicate that the concentrations of degradation products of the three SAs show a tendency to increase and then decrease, demonstrating that EBI can achieve efficient removal and further mineralization of SAs. Meanwhile, the results of the common product 4-Aminophenol produced during the degradation process further indicate that HO is the predominant reactive oxygen species (ROS). In addition, acute toxicity experiments with luminescent bacteria and predictions of ECOSAR procedures proved the toxic effects greatly decreased after the degradation. This study provides new ideas for achieving efficient and profound removal of emerging pollutants from the aquatic environment.

Efficient Degradation of 2-Mercaptobenzothiazole and Other Emerging Pollutants by Recombinant Bacterial Dye-Decolorizing Peroxidases

In recent years, concerns are being raised about the potential harmful effects of emerging pollutants (EPs) on human and aquatic lives. Extensive research is being conducted on developing efficient remediation strategies to target this new class of toxic pollutants. Studies focused on biological (enzyme-based) methods have shown potential as greener and possibly more economical alternatives to other treatment approaches, such as chemical methods. The current study focused on the use of recombinantly produced novel bacterial peroxidases, namely dye-decolorizing peroxidases (DyPs), to study their effectiveness in degrading a number of diverse EPs. In this context, a sensitive bioanalytical Liquid chromatography-tandem mass spectrometry (LCMSMS)-based method was developed to simultaneously detect a mixture of 31 EPs and to examine their degradability by a panel of seven different recombinant bacterial DyPs (rDyPs). We show that up to 9 of the 31 tested EPs could be degraded by at least one of the DyPs tested. The results also indicated that not all rDyPs behaved similarly in their abilities to degrade EPs, as some rDyPs (such as SviDyP and CboDyP) showed a promising potential to degrade EPs while others (such as ScDyP) were almost ineffective. Additionally, the role of redox mediators for effective emerging pollutant degradation by rDyPs was also examined, which showed dramatic improvement in the DyP-mediated degradation of five different EPs. Detailed analysis of 2-mercaptobenzothiazole degradation by SviDyP showed that six distinct breakdown products were generated. The present study showed for the first time that recombinant bacterial DyPs can be used for wastewater remediation by degrading a range of different EPs.

Efficient removal of antibiotic thiamphenicol by pulsed discharge plasma coupled with complex catalysis using graphene-WO3-Fe3O4 nanocomposites

Pulsed discharge plasma (PDP) induced complex catalysis for synergetic removal of thiamphenicol (TAP) was investigated using graphene-WO₃-Fe₃O₄ nanocomposites. The prepared samples were characterized systematically in view of the structure and morphology, chemical bonding state, optical property, electrochemical property and magnetic property. Based on characterization and TAP degradation, the catalytic performance followed: graphene-WO₃-Fe₃O₄>graphene-WO₃>WO₃, and the highest removal efficiency and kinetic constant could reached 99.3% and 0.070 min^-1, respectively. With increase of catalyst dosage, the removal efficiency firstly enhanced and then declined. Lower pH value was beneficial for TAP degradation. The prepared graphene-WO₃-Fe₃O₄ owed higher stability and lower dissolution rate of iron ion. The rGO-WO₃-Fe₃O₄ could decompose O₃ and H₂O₂ into more ·OH in PDP system. The degradation intermediates were characterized by fluorescence spectrograph, LC-MS and IC. Based on the detected intermediates and discrete Fourier transform (DFT) analysis, degradation pathway of TAP was proposed. Besides, the toxicity of intermediates was predicted. Finally, catalytic degradation mechanism of TAP by PDP with graphene-WO₃-Fe₃O₄ was summarized.

Peracetic acid-based advanced oxidation processes for decontamination and disinfection of water: A review

Peracetic acid (PAA) has attracted growing attention as an alternative oxidant and disinfectant in wastewater treatment due to the increased demand to reduce chlorine usage and control disinfection byproducts (DBPs). These applications have stimulated new investigations on PAA-based advanced oxidation processes (AOPs), which can enhance water disinfection and remove micropollutants. The purpose of this review is to conduct a comprehensive analysis of scientific information and experimental data reported in recent years on the applications of PAA-based AOPs for the removal of chemical and microbiological micropollutants from water and wastewater. Various methods of PAA activation, including the supply of external energy and metal/metal-free catalysts, as well as their activation mechanisms are discussed. Then, a review on the usage of PAA-based AOPs for contaminant degradation is given. The degradation mechanisms of organic compounds and the influence of the controlling parameters of PAA-based treatment systems are summarized and discussed. Concurrently, the application of PAA-based AOPs for water disinfection and the related mechanisms of microorganism inactivation are also reviewed. Since combining UV light with PAA is the most commonly investigated PAA-based AOP for simultaneous pathogen inactivation and micropollutant oxidation, we have also focused on PAA microbial inactivation kinetics, together with the effects of key experimental parameters on the process. Moreover, we have discussed the advantages and disadvantages of UV/PAA as an AOP against the well-known and established UV/H₂O₂. Finally, the knowledge gaps, challenges, and new opportunities for research in this field are discussed. This critical review will facilitate an in-depth understanding of the PAA-based AOPs for water and wastewater treatment and provide useful perspectives for future research and development for PAA-based technologies.

Enhancement of Sono-Fenton by P25-Mediated Visible Light Photocatalysis: Analysis of Synergistic Effect and Influence of Emerging Contaminant Properties

The main purpose is to figure out the involved synergistic effects by combining sono-Fenton using in situ generated H2O2 and the photocatalytic process of P25 under visible light (Vis/P25). Two emerging contaminants, dimethyl phthalate (DMP) and diethyl phthalate (DEP), with similar structure but different properties were selected to examine the influence of hydrophilic and hydrophobic properties of target pollutants. Results show that there is synergy between sono-Fenton and Vis/P25, and more significant synergy can be obtained with low dose of Fe3+ or Fe2+ (0.02 mM) and for more hydrophilic DMP. Based on systematic analysis, the primary mechanism of the synergy is found to be the fast regeneration of Fe2+ by photo-electrons from P25 photocatalysis, which plays the dominant role when the Fe3+/Fe2+ concentration is low (0.02 mM). However, at high Fe3+/Fe2+ concentration (0.5 mM), the photoreduction of Fe(III) to Fe2+ can play a key role with relatively low efficiency. By studying the degradation intermediates of both DMP and DEP, the degradation pathways can be determined as the hydroxylation of aromatic ring and the oxidation of the aliphatic chain. Better mineralization performance is achieved for DMP than that for DEP due to the enhanced utilization efficiency of H2O2 by accelerating Fe2+ regeneration.

Kinetic and mechanism study of UV/pre-magnetized-Fe0/oxalate for removing sulfamethazine

In this study, UV irradiated photochemical reactions of oxalate (Ox) with premagnetized-Fe⁰ (pre- Fe⁰) as the catalyst was used to degrade sulfamethazine (SMT). Magnetic field promoted the release of iron ion from Fe⁰ thus enhanced SMT and Ox removal in UV/pre- Fe⁰/Ox process. X-ray photoelectron spectroscopy demonstrated that the presence of UV and Ox promoted the transformation of Fe³⁺ to Fe²⁺ on Fe⁰, which enhanced the surface bound •OH (•OH_surf) generation. Ox inhibited the formation of iron (hydro)xides and enhanced the hydroxylation of Fe⁰ surface. •OH_surf was mainly responsible for SMT removal (44%), while UV direct photolysis and •OH in the solution both caused around 28% SMT removal. The process with Ox exhibited much higher efficiency in SMT degradation than that added with H₃PO₄, citric acid and ethylenediaminetetraacetic acid, which greatly expanded the chelate-modified Fenton processes and their treatment efficiency.