Degradation Of Sulfamethoxazole Research Articles

Simultaneous degradation of pharmaceuticals and personal care products in hospital wastewater using ozone under ultraviolet irradiation

The discharge of Pharmaceuticals and personal care products (PPCPs) from industries and hospitals are responsible for the contamination of water body with slow or non-degradable toxic compounds. The removal of these contaminants required advanced treatment process because of unable to treat by conventional wastewater treatment process. In this study, the degradation of PPCP compounds, including caffeine (CAF), atenolol (ATL), carbamazepine (CBZ), sulfamethoxazole (SMX), trimethoprim (TMP), and acetaminophen (ACT) was evaluated under exposure to 1.0 and 1.5 mg/L dissolved ozone (O3), both with and without ultraviolet (UV) irradiation (254 nm). Using liquid chromatography with tandem mass spectrometry, we determined that the removal efficiency for the targeted contaminants exceeded 95 % within just 20 min of exposure to both 1.0 and 1.5 mg/L O3. However, when treated with UV light alone, the removal efficiency was limited at 3 %–11 %. A combination treatment involving dissolved 1.5 mg/L O3 and UV light led to over 97 % removal within 7 min. This outcome was attributed to hydroxylation reactions, aromatic ring opening, oxidation, and mineralization facilitated by the HO and peroxide generated through the photolysis of O3. The degradation rate of PPCP compounds followed pseudo-first-order kinetics and showed a decrease in the presence of humic acid and hospital wastewater further decreased it. Moreover, O3/UV treatment generated lower-weight degradation products. The toxicity analysis revealed that these transformation products exhibited environmental benignity and minimal health risks which O3/UV treatment potentially minimizes the presence of harmful byproducts. These findings provide a foundation for developing combined hybrid systems for PPCP containing wastewater, containing membrane filtration with ozonation system.

Effects of nanoparticles on the anaerobic digestion properties of sulfamethoxazole-containing chicken manure and analysis of bio-enzymes

Abstract Medium-temperature anaerobic digestion experiments lasting for 55 days were conducted using sulfamethoxazole (SMX)-containing chicken manure in sequential batch reactors added with nano-Fe2O3 at a concentration of 300 mg·kg−1·TS or nano-C60 at a concentration of 100 mg·kg−1·TS. The effects of nanoparticles on the anaerobic digestion properties of SMX-containing chicken manure were assessed by measuring the following indicators: biogas production by anaerobic digestion, chemical parameters, enzyme concentrations, and bacterial diversity and changes in antibiotic concentrations over time. The law of bacterial degradation of SMX was analyzed. The results showed that (1) adding either nano-Fe2O3 or nano-C60 promoted biogas production by anaerobic production from chicken manure containing different concentrations of SMX, and the cumulative biogas production in Fe2O3 and nano-C60 increased by 35.4% and 130.7%, respectively. The final cumulative biogas productions in different groups were as follows: 3,712(CK), 4,281(S1), 3,968(S2), 4,061(S3), 4,498(S4), and 4,639(S5) mL and the final concentration of SMX residues varied between 99.79% and 99.94%; (2) Bacterial abundance at the phylum level: on day 1, Firmicutes and Bacteroidota were the main dominant bacterial phyla, with relative abundances of 45.13–68.53% and 26.12–48.32%, respectively. The addition of nanoparticles increased the abundance of Bacteroidota in S4 and S5 significantly. The abundance of Bacteroidota was slightly higher in the group added with nanoparticles than in S2. On day 50, Firmicutes became the dominant bacterial phylum, and its relative abundance varied little across the groups, ranging from 90.87% to 94.54%; (3) At different stages, the bacterial community structure at the genus level was dramatically affected by substrates. As nutrients were being depleted, some bacterial communities lost their original competitive advantages. On day 5, the relative abundance of Prevotella increased. Especially, the relative abundances of Prevotella in S4 and S5 added with nanoparticles were lower than that in S2 by 8–10%. On day 15, the relative abundance of Prevotella in S2 decreased compared with the control group CK. A decrease was also observed in S4 and S5, although to a smaller extent than in S2.

Effective periodate activation by the ball-milled bimetallic zero-valent iron/manganese oxides catalyst for sulfamethoxazole degradation

Developing a green and efficient catalyst for oxidant activation to tackle refractory organics pollution is challenging for water purification. In this study, we prepared a zero-valent iron-based bimetallic catalyst (ZVI/Mn3O4) for periodate (PI) activation using a simple and convenient ball-milling method. Electrochemical characterization and theoretical calculations confirm that the synergy between Fe and Mn enables the ZVI/Mn3O4 system to exhibit higher electron transfer efficiency compared to its individual components. Consequently, the ZVI/Mn3O4/PI system demonstrated enhanced PI activation and significantly improved removal of sulfamethoxazole (SMX), with reaction rates being 18.61 to 57.01 times higher than the comparison systems. The influence of various physicochemical parameters on SMX removal was investigated, confirming the wide tolerance ZVI/Mn3O4/PI system towards multiple aqueous matrices. Furthermore, the scalability of this system for industrial applications was validated through the preparation of larger batches of catalysts (4.21 g per batch) and testing in a custom-designed magnetic plate continuous-flow reactor. Quenching experiments and electron spin resonance tests confirmed that •O2– and 1O2 were the primary reactive species responsible for SMX degradation, with no toxic iodine byproducts detected, attributed to the carefully designed catalyst, which optimized the interaction between PI and the catalyst. Based on these findings, a potential catalytic mechanism and degradation pathway were proposed, highlighting ZVI's role as an electron pump to enhance Mn3O4's activation of PI. Additionally, toxicity assessments via prediction, zebrafish cultivation, wheat germination, and E. coli culture confirmed the excellent detoxification capability of ZVI/Mn3O4/PI system for SMX degradation. Overall, this work provides a new research paradigm for the convenient manufacture of ZVI-based catalysts and the development of advanced techniques for PI activation in water purification.

Unveiling the heterojunction of Fe3O4@MXene nanocatalyst for ultrafast degradation of antibiotics via non-radical pathway

The transfer of advanced oxidation processes (AOPs) to real-world applications faces several technology challenges involving oxidation performance, catalyst cost, poor reactive oxygen species (ROS) yield, and long-term stability. This work aims to develop a reactive, efficient, and stable MXene-based nanocatalyst, namely Fe3O4@Ti3C2Tx, for ultrafast removal of the selected sulfonamide antibiotics. As revealed by extensive nanocatalyst characterization, the MXene surface not only anchors Fe/Fe3O4 nanoparticles (NPs) but also prevents NP agglomeration. Notably, the conductive interface between MXene and Fe3O4 promotes the Fe(II)/Fe(III) redox cycle and accelerates peroxymonosulfate (PMS) activation. The Fe3O4@Ti3C2Tx demonstrates excellent catalytic activity by achieving complete sulfamethoxazole (SMX) degradation within 6 min and maintained its catalytic activity after 5 continuous cycles. In the Fe3O4@Ti3C2Tx/PMS system, multiple ROS (e.g., •OH, SO4•-, O2•-) are involved but 1O2 was found to be the primary ROS for SMX degradation. The presence of co-exiting inorganic impurities and pH changes may hinder SMX degradation. Finally, elucidating possible degradation pathways of SMX would greatly aid in treating antibiotic-containing wastewater.

Regulating the Electronic Structure of Cu Single-Atom Catalysts toward Enhanced Electro-Fenton Degradation of Organic Contaminants via 1O2 and •OH.

Heterogeneous electro-Fenton degradation with 1O2 and •OH generated from O2 reduction is cost-effective for the removal of refractory organic pollutants from wastewater. As 1O2 is more tolerant to background constituents such as salt ions and a high pH value than •OH, tuning the production of 1O2 and •OH is important for efficient electro-Fenton degradation. However, it remains a great challenge to selectively produce 1O2 and improve the species yield. Herein, the electronic structure of atomically dispersed Cu-N4 sites was regulated by doping electron-deficient B into porous hollow carbon microspheres (CuBN-HCMs), which improved *O2 adsorption and significantly enhanced 1O2 selectivity in electro-Fenton degradation. Its 1O2 yield was 2.3 times higher than that of a Cu single-atom catalyst without B doping. Meanwhile, •OH was simultaneously generated as a minor species. The CuBN-HCMs were efficient for the electro-Fenton degradation of phenol, sulfamethoxazole, and bisphenol A with a high mineralization efficiency. Its kinetic constants showed insignificant changes under various anions and a wide pH range of 1-9. More importantly, it was energy-efficient for treating actual coking wastewater with a low energy consumption of 19.0 kWh kgCOD-1. The superior performance of the CuBN-HCMs was contributed from 1O2 and •OH and its high 1O2 selectivity.

Multifunctional copper sulfide urchin‐like nanostructures for adsorption and photocatalysis of water contaminants

We reported here a one‐step chemical route to prepare nanocomposites comprising CuS nanophases supported on GO sheets with magnetic properties. The synthesis reported here combines such materials in single‐nanostructures that show morphological features well‐suited for wastewater treatment. The photocatalytic performance of CuS/GO nanocomposites was investigated towards the removal of a common organic dye (rhodamine‐B) and sulfamethoxazole (SMX), which is an antibiotic considered a water contaminant of emerging concern. The RhB and SMX adsorption efficiency of CuS/GO and Fe3O4/GO/CuS hybrids, as well as CuS particles, was significantly higher than GO or Fe3O4/GO. Overall, the CuS‐based magnetic and CuS/GO hybrids have shown the capacity to uptake more than 80% of RhB or SMX, after 120 minutes. Under blue‐led irradiation, almost complete degradation of RhB was achieved in the presence of CuS/Fe3O4/GO, after 180 minutes; and higher than 85% degradation of SMX, after 240 minutes of irradiation. The photocatalytic behaviour of nanocomposites was best described by the first‐order kinetic model, for which k values for degradation of RhB and SMX followed the order: CuS/Fe3O4/GO>CuS/GO>CuS. The tricomponent CuS/Fe3O4/GO can be easily recovered after use and be reused to maintain their high photocatalytic performance, thus providing sustainable and cost‐effective hybrid solution for water treatment.

Kinetic Modelling of Aromaticity and Colour Changes during the Degradation of Sulfamethoxazole Using Photo-Fenton Technology

Sulfamethoxazole (SMX) is an antibiotic that is extensively used in veterinary medicine, and its occurrence in wastewater and surface water can reach up to 20 μg/L. SMX is categorized as a pollutant of emerging concern by the US EPA due to its persistence and effects on humans and the environment. In this study, photo-Fenton technology is proposed for the removal of SMX. Aqueous solutions of SMX (50.0 mg/L) are treated in a 150 W UV photoreactor, using [Fe2+]0 = 0.5 mg/L and varying [H2O2]0 = 0–3.0 mM. During the reaction, colour (AU) was assessed along with SMX (mg/L), turbidity (NTU), and TC (mg/L). SMX degrades to aromatic intermediates with chromophoric groups, exhibiting colour (yellow to brown) and turbidity. As these intermediates are mineralized into CO2 and H2O, the colour and turbidity of the water lose intensity. Using a molar ratio of 1 mol SMX:10 mol H2O2, the maximum degradation of aromatic species takes place (71% elimination), and colourless water with turbidity < 1 NTU is obtained. A kinetic modelling for aromaticity loss and colour formation as a function of the oxidant concentration has been proposed. The application of this model allows the estimation of oxidant amounts for an efficient removal of SMX under environmentally friendly conditions.

Tailored MXene-derived nano-heterostructure oxides for peroxymonosulfate activation in the treatment of municipal wastewaters.

Nowadays, in the field of environmental protection, a huge effort is focused on efficient and sustainable processes to treat wastewaters. The current study emphasizes the photocatalytic performance of TiNbOx, a nano-heterostructure material derived from the oxidation of (Ti0.75Nb0.25)2CTx MXene. The TiNbOx nano-heterostructure exhibited remarkable performance in the degradation of caffeine (CAF) and sulfamethoxazole (SMX) under UVA irradiation in the presence of peroxymonosulfate (PMS). Under optimal conditions, 0.2 g L-1 of TiNbOx, 0.5 mM PMS and 50 μM concentration of pollutants and natural pH of deionized water, we observed a complete degradation of SMX and 91% degradation of CAF. Scavenging studies provided evidence for the involvement of ˙OH and SO4˙- in the degradation of the pollutants, which was also supported by indirect techniques of electron paramagnetic resonance (EPR) spectroscopy. The degradation pathway of the pollutants was analyzed by liquid chromatography-mass spectrometry (LC-MS) and several mechanisms were suggested including hydroxylation and isoxazole ring-opening reactions. In addition, X-ray photoelectron spectroscopy (XPS) supported the proposed degradation mechanism. The reusability test underscored the high stability and efficiency of TiNbOx. Moreover, the significance of this research was emphasized by conducting degradation studies in tap water (TW) and tertiary effluents of the wastewater (WW) treatment plant in Bratislava. Under optimal conditions, 49% and 30% CAF were degraded in TW and WW, respectively, after 12 hours of reaction. For SMX, 68% and 67% degradations were obtained in TW and WW, respectively.

Enhanced activation of peroxymonosulfate by introducing Co/Fe atoms in LaCoO3-biochar derived catalysts for the degradation of sulfamethoxazole

In this study, a novel perovskite-biochar composite, LaCoMO3-C (LaCoM-C, M = Cu, Fe), was designed using a co-precipitation-calcination strategy and employed activation of peroxymonosulfate (PMS) for efficiently degrade sulfamethoxazole (SMX). The degradation results indicated that the LaCoCu-C/PMS system could effectively degrade 95 % of SMX within 7 min with a kinetics rate constant of 0.33 min−1, which was about 2.21, 6.64 and 3.7 times that of LaCoFe-C, LaCoCu and LaCo-C, respectively. The biochar skeleton greatly increased the specific surface area and uniform distribution of surface active sites of the composites, leading to the optimization of its catalytic performance. Density Functional Theory (DFT) calculations demonstrated that the adsorption capacity of the composites with PMS could be improved by introducing Cu/Fe elements into the interfacial structure of the composites, while Co was identified as the dominant active site. Combined with quenching test, electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy (XPS) analyses, we demonstrated the generation of reactive oxygen species including 1O2, •OH, SO4•- and O2•-, and revealed that the oxidation process of Cu+/Cu2+ and Co2+/Co3+ on the LaCoCu-C surface contributes to PMS activation. This work constitutes an insightful reference for the development of catalysts based on perovskite B-site for efficient activation of PMS.

Weak magnetic field for enhanced degradation of sulfamethoxazole by the CoFe2O4/PAA system: Insights into performance and mechanism

In this work, a novel approach coupling a heterogeneous weak magnetic field (WMF) with the CoFe2O4/peroxyacetic acid (PAA) system was employed to enhance the degradation of sulfamethoxazole (SMX). Under the optimized conditions of 50 mT WMF, 0.1 g/L CoFe2O4, 0.2 mM PAA, and initial pH 6.0, a complete degradation of 10 μM SMX was achieved in 25 min, exhibiting a high synergistic coefficient of 1.61. This result indicates a significant synergistic effect among WMF, CoFe2O4, and PAA in effectively degrading SMX. The introduction of WMF did not alter the pH application range of the CoFe2O4/PAA system. Furthermore, the degradation efficiency of SMX by the CoFe2O4/PAA/WMF system was significantly reduced in the presence of humic acid (HA) and bicarbonate ions (HCO3−), while chloride ions (Cl−) exhibited a minor inhibitory effect. Quenching experiments and electron paramagnetic resonance (EPR) analysis reveal that WMF did not alter the types of reactive oxygen species (ROS) generated in the CoFe2O4/PAA system. The degradation of SMX in the CoFe2O4/PAA/WMF system involved both radical (CH3C(O)O∙ and CH3C(O)OO∙) and non-radical (1O2) oxidation pathways, driven by the redox cycling between ≡Co2+/≡Co3+ and PAA, as well as the rapid adsorption and transformation of oxygen (O2) at oxygen vacancies (OV), respectively. The presence of WMF enhanced the utilization of PAA by CoFe2O4 by improving the convection and mass transport in the solution, facilitating the formation of superoxide anion (O2∙−) and supplemented lattice oxygen (O2−) through the directional migration of paramagnetic O2 towards the CoFe2O4 surface, thus significantly promoting ROS formation. Additionally, the degradation pathways of SMX in the CoFe2O4/PAA/WMF system were proposed based on density functional theory (DFT) calculations and the detected transformation products (TPs). The toxicity of SMX was effectively reduced, as verified by predictions from the Ecological Structure-Activity Relationship Model (ECOSAR) procedure. The excellent catalytic performance, reusability, and effective degradation of various organic pollutants demonstrated by the CoFe2O4/PAA/WMF system suggest its potential as a promising strategy for water treatment.

Efficient sulfamethoxazole biotransformation and detoxification by newly isolated strain Hydrogenophaga sp. SNF1 via a ring ortho-hydroxylation pathway

Sulfonamides are frequently detected with high concentrations in various environments and was regarded as a serious environmental risk by fostering the dissemination of antibiotic resistance genes. This study for the first time reported a strain SNF1 affiliated with Hydrogenophaga can efficiently degrade sulfamethoxazole (SMX). Strain SNF1 prefers growing under extra carbon sources and neutral condition, and could degrade 500 mg/L SMX completely within 16 h. Under the conditions optimized by response surface method (3.11 g/L NaAc, 0.77 g/L (NH4)2SO4, pH = 7.53, and T = 34.38 ℃), a high removal rate constant 0.5104 /h for 50 mg/L SMX was achieved. Coupling the intermediate products identification with comparative genomic analysis, a novel SMX degradation pathway was proposed. Unlike Actinomycetota degraders, SMX was deaminized and ring ortho-hydroxylated in strain SNF1 using a Rieske dioxygenase in combination with glutamine synthetase system. Rieske dioxygenase gene expression was up-regulated by 1.09 to 6.02-fold in response to 100 mg/L SMX. When SMX is fully degraded, its antimicrobial activity drops by over 90 %, and its anticipated toxicity to aquatic organisms were overall reduced. These findings provided new insights into SMX-degrading microorganisms and mechanisms and highlighted the potential of Hydrogenophaga. sp. SNF1 for biological elimination of SMX from wastewater.

Electrochemistry enhanced multi-stage biological contact oxidation treating sulfamethoxazole wastewater: Performance, degradation pathway and microbial community

Clean and economical techniques are in urgent need for improving antibiotics removal from wastewater. In this study, a multi-stage bio-contact oxidation reactor (BCOR) was constructed and further enhanced by electrochemistry to treat sulfamethoxazole (SMX) wastewater. The stimulatory effects of the electrochemistry were investigated together with the succession of microbial communities as well as the possible conversion pathways of SMX. The results showed that the SMX and chemical oxygen demand removal rates reached up to 92.96 ± 0.62 % and 91.42 ± 0.82 % at electric current density of 2.0 mA/cm2. Electrochemistry enhancement induced bone cleavage and oxidation transformation pathways of SMX while reduced the toxicity of degrading intermediates. Moreover, electrochemistry enhancement stimulated the growth of Klebsiella and Rhodobacter as well as the fermentation, chemoheterotrophy and aerobic_chemoheterotrophy functions which further promoted the SMX removal. This study revealed the biochemical removal mechanisms of SMX degradation and manifested the feasibility of combing electrochemistry with BCOR to treat antibiotics wastewater with low energy consumption.

Sulfamethoxazole degradation pathways in wastewater treatment: Bayesian network-based approach for a meta-analysis of scientific papers.

Given the widespread presence of micropollutants in urban water systems, it is imperative to gain a comprehensive understanding of their degradation pathways. This paper focuses on sulfamethoxazole (SMX) as a model molecule due to its extensive study, aiming to elucidate its degradation pathways in biological (BIO) and oxidative (AOP) processes. Numerous reaction pathways are outlined in scientific papers. However, a significant deficiency in current methodologies has led to the development of a novel meta-analytical approach, seeking consensus among researchers by synthesizing data from studies characterized by their heterogeneity and contradictions. As an innovative alternative, probabilistic graphical models such as Bayesian networks (BNs) could illuminate the relationships and dependencies between various transformation products, providing a holistic view of the degradation process. Based on the analysis of an extensive bibliography gathering more than 45 articles for more than 140 molecules and 177 reaction pathways, this study proposes a meta-analysis methodology based on Bayesian networks.

Platinum oxide-based peracetic acid activation for efficient degradation of typical antibiotic

Peracetic acid (PAA)-based Advance Oxidation Process (AOP) is now used to treat pharmaceutically contaminated wastewater. Herein, PAA is heterogenically activated to degrade sulfamethoxazole (SMX) taking platinum oxide (PtO2) as a catalyst for the first time. PtO2/PAA system with good synergetic effect achieved 100 % SMX degradation in 75 min.Its corresponding kinetic rate constant (0.072 min−1) was exceptionally higher than six other Transition Metal/PAA-based systems tested as well as than PtO2 or PAA alone. The degradation improved by augmenting PAA and PtO2 inputs. Radical scavenging and electron paramagnetic resonance pointed acetylperoxy (CH3C(O)OO·) and acetoxyl (CH3C(O)O·) as the main reactive radicals attributing SMX abatement. X-ray photoelectron spectroscopy and diffraction along with electrochemical tests (cyclic voltammetric curve, electrochemical impedance spectra, and I-t curve) recommended that the electron transfer of Pt2+/Pt4+ also facilitated PAA activation. Density Functional Theory (DFT) assisted in predicting the reaction sites on SMX molecules. Four degradation pathways are proposed with the help of DFT calculations and eight intermediate products identified by High-Performance Liquid Chromatography Mass-Spactrometry. Dissolved organic matter, anions and different waterbodies had tolerable degradation inhibition. Efficient reactivity and adequate stability attest PtO2 as an ideal catalyst for oxidative degradations. The findings offer valuable insights into a novel, sustainable, and efficient approach to treat drug-contaminated wastewater.

Ecologically friendly remediation of groundwater sulfamethoxazole contamination: Biologically synergistic degradation by thermally modified activated carbon-activated peracetic acid in porous media

This study examines the efficacy and environmental impact of peracetic acid (PAA) activated by thermally modified activated carbon (AC600) for degrading antibiotics in actual groundwater. Laboratory-scale experiments evaluated the system's effects on contaminant degradation, ecological balance, and substance cycling in the hyporheic zone. Our findings demonstrated the effectiveness of the AC600/PAA system in removing sulfamethoxazole (SMX) from groundwater porous media. Additionally, the AC600/PAA system synergistically interacted with the in-situ microbiota of the hyporheic zone, producing more fragmented degradation products without increasing mixed toxicity. Bacterial abundance increased post-reaction, with notable alterations in the bacterial community and enhanced bacterial metabolism. Key genera such as Lysobacter thrived in the treated environment, playing critical roles in microbiota modification and SMX degradation. The pH remained stable before and after the reaction, while dissolved organic carbon content increased. Overall, our results highlight the promising potential of PAA activation by carbonaceous materials as a low-impact, ecologically friendly technology for in-situ remediation of organic pollutants in groundwater, characterized by high compatibility and biosynthesis.

Boosting oxygen storage capacity of Fe-Cu bimetallic catalysts through sulfide modification for efficient and selective molecular oxygen activation

Molecular oxygen (O2), a reactive oxygen species precursor, has great potential for water purification, but its spin-forbidden resistance hinders its direct involvement in the redox reactions of organic compounds under mild ambient conditions. In this study, a facile strategy was employed to synthesize sulfide-modified Fe-Cu bimetallic catalysts (FeCu-S) to enhance the activation efficiency of O2. The results showed that the FeCu-S material exhibited a tenfold increase in O2 activation compared to that of the control group, primarily attributed to the increased specific surface area of the catalysts with an optimized Fe/Cu site distribution and promoted generation of Cu-containing crystalline phases (e. g., CuFeS2 and CuO) to significantly enhanced the oxygen storage capacity. Moreover, such Cu-containing crystalline phases strengthened surface electron transfer, thus remarkably promoting the selective generation of singlet oxygen (1O2) for sulfamethoxazole (SMX) degradation. The FeCu-S/O2 system maintained high activity after the fifth recycle with stable reaction pH and negligible leaching of Cu and Fe ions, also exhibited great performance in the advanced treatment of the real biological effluent and ultrafiltration effluent from landfill leachate, confirming its great potential for practical water purification applications.

Iron metal-organic framework nanofiber membrane for the integration of electro-Fenton and effective continuous treatment of pharmaceuticals in water

In this study, an iron metal-organic framework (Fe-MOF) was synthesized and immobilized by electrospinning technique with the objective of obtaining a membrane composed of nanofibers of this material (Fe-MOF nanofiber membrane). The characterization performed by XRD, TEM, SEM, EDS mapping and FTIR confirmed the correct synthesis of Fe-MOF as well as its correct retention in the elaborated membranes. The usefulness and effectiveness of the Fe-MOF nanofiber membrane as a catalyst for the electro-Fenton process was evaluated by performing sulfamethoxazole degradation tests. Different parameters such as the effect of intensity (25 and 100 mA), the effect of the drug initial concentration (10–50 mg/L) and the reusability of membranes were studied. Then, the degradation of a drug mixture formed by sulfamethoxazole and antipyrine was evaluated, reaching a degradation of 92.10 % and 87.43 % respectively for each drug in 4 h at 25 mA. In addition, the identification of reactive oxygen species was ascertained by scavenger assays. The study of degradation products was also carried out and their toxicity was predicted by ECOSAR program, concluding that the environmental toxicity would disappear with mineralization. Finally, given the good results obtained in batch tests, the behavior of the process was studied in a system that works continuously, achieving a stable degradation of 83.10 % in the case of treatment with a mixture of drugs. This confirmed the stability of the Fe-MOF nanofiber membrane, as well as, its catalytic activity, making it suitable for long-term treatments.

Peroxymonosulfate Activation by Fe@N Co-Doped Biochar for the Degradation of Sulfamethoxazole: The Key Role of Pyrrolic N

In this study, Fe, N co-doped biochar (Fe@N co-doped BC) was synthesized by the carbonization–pyrolysis method and used as a carbocatalyst to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. In the Fe@N co-doped BC/PMS system, the degradation efficiency of SMX (10.0 mg·L−1) was 90.2% within 40 min under optimal conditions. Radical quenching experiments and electron spin resonance (ESR) analysis suggested that sulfate radicals (SO4•−), hydroxyl radicals (•OH), and singlet oxygen (1O2) participated in the degradation process. After the reaction, the proportion of pyrrolic N decreased from 57.9% to 27.1%. Pyrrolic N served as an active site to break the inert carbon network structure and promote the generation of reactive oxygen species (ROS). In addition, pyrrolic N showed a stronger interaction with PMS and significantly reduced the activation energy required for the reaction (∆G = 23.54 kcal/mol). The utilization potentiality of Fe@N co-doped BC was systematically evaluated in terms of its reusability and selectivity to organics. Finally, the intermediates of SMX were also detected.

Constructing Tandem Fenton-like Reaction Systems Based on Structure Adaption to Boost Water Contaminant Mineralization Efficiency.

Mineralization of emerging contaminants by using advanced oxidation processes (AOPs) is a desirable option to ensure water safety, but still challenged by the excessive chemical and/or energy input. Here, we conceptually proposed the tandem reaction system (TRS) of different reactive oxygen species (ROS) based on structure adaption of target contaminants. To construct a model TRS, we first realized highly selective generation of three classical ROS (1O2, HO• and SO4•-) by peroxymonosulfate activation in an electrochemical Fenton-like system, where three replaceable Fe-centered cathodes were rationally designed as electronic mediator. The 1O2+SO4•--TRS exhibited nearly 100% mineralization of sulfamethoxazole (SMX), whereas only 34.2%, 56.2% and 60.8% for each of the single 1O2/HO•/SO4•--AOP systems. Mechanism exploration of SMX degradation in TRS evidenced that the initial reaction with 1O2 selectively destructed the sulfonamide bridge of SMX to form p-aminobenzenesulfonic acid, which will be vulnerable to sequent SO4•- attack to facilitate mineralization. Successful extendibility of 1O2+SO4•--TRS to other sulfonamide antibiotics and 1O2+HO•-TRS to phenolic and arylcarboxylic compounds, as well as the demonstration of 1O2+SO4•--TRS in treatment of three actual pharmaceutical wastewaters strongly support that TRS is a powerful and sustainable strategy to enhance the mineralization of emerging contaminants in water.

Constructing Tandem Fenton‐like Reaction Systems Based on Structure Adaption to Boost Water Contaminant Mineralization Efficiency

Mineralization of emerging contaminants by using advanced oxidation processes (AOPs) is a desirable option to ensure water safety, but still challenged by the excessive chemical and/or energy input. Here, we conceptually proposed the tandem reaction system (TRS) of different reactive oxygen species (ROS) based on structure adaption of target contaminants. To construct a model TRS, we first realized highly selective generation of three classical ROS (1O2, HO• and SO4•–) by peroxymonosulfate activation in an electrochemical Fenton‐like system, where three replaceable Fe‐centered cathodes were rationally designed as electronic mediator. The 1O2+SO4•–‐TRS exhibited nearly 100% mineralization of sulfamethoxazole (SMX), whereas only 34.2%, 56.2% and 60.8% for each of the single 1O2/HO•/SO4•–‐AOP systems. Mechanism exploration of SMX degradation in TRS evidenced that the initial reaction with 1O2 selectively destructed the sulfonamide bridge of SMX to form p‐aminobenzenesulfonic acid, which will be vulnerable to sequent SO4•– attack to facilitate mineralization. Successful extendibility of 1O2+SO4•–‐TRS to other sulfonamide antibiotics and 1O2+HO•‐TRS to phenolic and arylcarboxylic compounds, as well as the demonstration of 1O2+SO4•–‐TRS in treatment of three actual pharmaceutical wastewaters strongly support that TRS is a powerful and sustainable strategy to enhance the mineralization of emerging contaminants in water.