Elimination Of Sulfamethoxazole Research Articles

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.

Insights on aggregation-algae consortium based removal of sulfamethoxazole: Unraveling removal effect, enhanced method and toxicological evaluation

The escalating occurrence of the antibiotic Sulfamethoxazole (SMX) in the environment presents a significant global threat to ecological systems and human health. Despite the growing interest in using microalgae for antibiotic biodegradation, strategies to enhance SMX elimination remain underexplored. In this study, we isolated a novel aggregation-algae consortium (AAC) from a municipal wastewater treatment plant (WWTP) and examined its potential for SMX removal, optimized culture conditions, SMX metabolite fate and the physicochemical impact on microalgal cells. The findings revealed that the AAC demonstrated remarkable resistance to SMX, even at concentrations as high as 10 mg/L, and could degrade SMX via free radical reactions. Although ion repulsion limited the biodegradation of AAC, the addition of peptone and yeast extract resulted in a significant enhancement, increased by 16.71%, 39.12% and 46.77% of three SMX groups. Moreover, AAC exhibited exceptional adaptability in real wastewater, achieving removal of 87.05%, 97.39% and 20.80% for total dissolved nitrogen, total dissolved phosphorus and SMX, respectively. The decreased degradation toxicity of SMX following AAC treatment was further validated by ECOSAR software and in vitro tests using Caenorhabditis elegans. This study advanced our understanding of SMX biodegradation and provided a novel approach for treating wastewater contaminated with SMX.

Developing a novel continuous-flow cascade photocatalytic system for effective sulfamethoxazole elimination from hospital wastewater

In this study, we introduce a novel continuous-flow cascade photocatalytic system specifically designed to efficiently remove sulfamethoxazole (SMX) from hospital wastewater, addressing the critical need for sustainable pharmaceutical wastewater treatment. The system utilizes a carbon sponge-based TiO2 photocatalyst synthesized via a hydrothermal process under mild conditions. The system’s design incorporates multiple stages in a cascade configuration, meticulously optimized to enhance photocatalytic efficacy, thereby significantly improving the rate of SMX elimination while minimizing energy consumption. The study encompasses comprehensive characterization of the photocatalyst, including matching its absorption spectrum to the emission spectrum of the light source, as well as fine-tuning key operational parameters such as catalyst quantity, flow rates, and cascade configuration. Real-world application tests confirm the system’s efficiency, achieving approximately 80 % SMX removal efficiency alongside a notable reduction in Chemical Oxygen Demand (COD) levels. Furthermore, the system’s energy efficiency, as reflected by an Electrical Energy per Order (EEO) value of 7.53 kWh/m3, highlights its potential for scalable and sustainable wastewater treatment solutions. This study not only contributes significantly to the field of environmental catalysis but also represents a significant advancement in sustainable environmental management, offering a promising solution to the urgent challenge of pharmaceutical pollution in water sources.

Application of Membrane Bioreactor (MBR) for Antibiotic Elimination From Wastewater

In this study, a membrane bioreactor – MBR system at laboratory-scale was designed to remove sulfamethoxazole (SMX) in water. The system consists of a 8-liter aerobic tank combined with a hollow fiber micro filtration membrane (MF). Influent flow rate of wastewater was 15,84 L/day. Affecting factors to treatment efficiencies (organic pollutants and antibiotics) such as contact time and initial antibiotic concentration were investigated. Experimental results indicated that wastewater with initial parameters COD, NH4+, NO3-, PO43- were respectively 240, 9,4, 37,5, 6,3 mg/L, the treatment efficiencies achieved were respectively at 63,4, 89,7, 78,1, and 79,8%. The removal efficiencies of the wastewater containing SMX (concentrations range from 0,052 to 0,268 mg/L) for COD and NH4+ decreased by 4,2 and10,9% respectively, and for NO3- and PO43- increased by about 4,5 and 7,9%, correspondingly. Overall SMX elimination performance is about 49,7%.

Boron and nitrogen hydrothermal co-doped sludge biochar towards efficiently activate peroxymonosulfate for sulfamethoxazole degradation

Designing efficient catalyst for peroxymonosulfate (PMS) activation is beneficial for eliminating the adverse effects of sulfamethoxazole (SMX) on human health. A novel boron (B) and nitrogen (N) co-doped sludge biochar (BNSBC) was synthesized by one-pot hydrothermal activation, and its remarkable PMS activation performance facilitated the rapid elimination of SMX from water. The degradation rate of SMX by BNSBC/PMS system could reach 92.1% within 60 min ([SMX]0 = 10 mg/L, [BNSBC]0 = 0.4 g/L, [PMS]0 = 1 mM). B and N exhibited the synergistic enhancement effects on the physico-chemical characteristics of SBC, and abundant pores, defects, CO, -O-B-O-, graphitic-N and pyridinic N were confirmed as the main active sites of BNSBC for PMS activation. Characterization, quenching, electron paramagnetic resonance (EPR) and electrochemical tests proved that non-radicals of surface-bound, 1O2 and electron transfer were the main contributors to SMX degradation. The high anti-interference of BNSBC/PMS system to pH range, co-existing inorganic anions and organic matter guaranteed its outstanding purification performance for SMX in diverse environmental waters. Four potential degradation pathways of SMX in BNSBC/PMS system were proposed by its intermediates identification and density functional theory (DFT) calculation, and pathway Ⅳ was the main one. The toxicity levels of its intermediates were lower than that of SMX regardless of chronic and acute toxicity. Also, BNSBC/PMS system exhibited the board-spectrum removal performance for other typical antibiotics (e.g., sulfadiazine (SDZ), sulfamethoxypyridazine (SMP), ciprofloxacin (CIP), tetracycline (TC)). BNSBC/PMS has great application potential for eliminating diverse antibiotics in actual wastewater due to its high tolerance to complex environmental conditions and outstanding detoxification ability, also it offers a harmless disposal approach for sludge.

Sulfamethoxazole removal and fuel-feedstock biomass production from wastewater in a phyto-Fenton process using duckweed culture

The phyto-Fenton process, which generates hydroxyl radicals through Fenton and Fenton-like reactions using plant-derived hydrogen peroxide (H2O2) and ferrous iron (Fe (II)) can degrade organic pollutants. Duckweed, an aquatic plant, is promising for a co-beneficial phytoremediation process that combines wastewater treatment and biomass production for biofuel feedstock. However, the phyto-Fenton process using duckweed has not been extensively studied. Because sulfamethoxazole (SMX), a major antibiotic, is distributed widely and is an emerging contaminant, its effective removal from contaminated water is necessary. The present study investigated the possibility of the simultaneous efficient removal of SMX from polluted water and biomass production for fuel feedstock by the phyto-Fenton process using duckweed. This is the first attempt to demonstrate the co-benefits of SMX removal and biomass production using duckweed. Intracellular H2O2 was produced using four duckweeds, Lemna aequinoctialis, L. minor, Landolina punctata, and Spirodela polyrhiza, in the range of 16.7–24.6 μ mol g−1 fresh weight, and extracellular H2O2 was released into the water phase. Consequently, duckweed could be used as an H2O2 supply source for the phyto-Fenton process. Specifically, 0.5 g fresh duckweed almost completely eliminated 1 mg L−1 SMX after 5 d in 50 mL sterile modified Hoagland solution containing 10 mM Fe (II). Fe (II)-dependent elimination of SMX indicated the occurrence of phyto-Fenton reaction. The phyto-Fenton process using duckweed effectively removed SMX. S. polyrhiza duckweed similarly removed 1 mg L−1 SMX even in sewage effluent containing other organic contaminants. During this treatment, duckweed biomass was generated at 7.95 g dry weight m−2 d−1, which was converted into methane at 353 normal liters CH4 kg−1 volatile solids by anaerobic digestion. For the first time, this study clearly demonstrates the potential for simultaneous SMX removal and biomass production from SMX-contaminated wastewater using duckweed.

Protocatechuic acid enhanced the selective degradation of sulfonamide antibiotics in Fe(III)/peracetic acid process under actually neutral pH conditions

The practical application of the Fe-catalyzed peracetic acid (PAA) processes is seriously restricted due to the need for narrow pH working range and poor anti-interference capacity. This study demonstrates that protocatechuic acid (PCA), a natural and eco-environmental phenolic acid, significantly enhanced the removal of sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions (6.0–8.0) by complexing Fe(III). With sulfamethoxazole (SMX) as the model contaminant, the pseudo-first-order rate constant of SMX elimination in PCA/Fe(III)/PAA process was 63.5 times higher than that in Fe(III)/PAA process at pH 7.0, surpassing most of the previously reported strategies-enhanced Fe-catalyzed PAA processes (i.e., picolinic acid and hydroxylamine etc.). Excluding the primary contribution of reactive species commonly found in Fe-catalyzed PAA processes (e.g., •OH, R-O•, Fe(IV)/Fe(V) and 1O2) to SMX removal, the Fe(III)-peroxy complex intermediate (CH3C(O)OO-Fe(III)-PCA) was proposed as the primary reactive species in PCA/Fe(III)/PAA process. DFT theoretical calculations indicate that CH3C(O)OO-Fe(III)-PCA exhibited stronger oxidation potential than CH3C(O)OO-Fe(III), thereby enhancing SMX removal. Four potential removal pathways of SMX were proposed and the toxicity of reaction solution decreased with the removal of SMX. Furthermore, PCA/Fe(III)/PAA process exhibited strong anti-interference capacity to common natural anions (HCO3−, Cl−and NO3−) and humic acid. More importantly, the PCA/Fe(III)/PAA process demonstrated high efficiency for SMX elimination in actual samples, even at a trace Fe(III) dosage (i.e., 5 μM). Overall, this study provided a highly-efficient and eco-environmental strategy to remove sulfonamide antibiotics in Fe(III)/PAA process under actually neutral pH conditions and to strengthen its anti-interference capacity, underscoring its potential application in water treatment.

Comparative study on the activation of peroxymonosulfate and peroxydisulfate by Ar plasma-etching CNTs for sulfamethoxazole degradation: Efficiency and mechanisms

Sulfamethoxazole (SMX), a widely utilized antibiotic, was continually detected in the environment, causing serious risks to aquatic ecology and water security. In this study, carbon nanotubes (CNTs) with abundant defects were developed by argon plasma-etching technology to enhance the activation of persulfate (PS, including peroxymonosulfate (PMS) and peroxydisulfate (PDS)) for SMX degradation while reducing environmental toxicity. Obviously, the increase of ID/IG value from 0.980 to 1.333 indicated that Ar plasma-etching successfully introduced rich defects into CNTs. Of note, Ar-90-CNT, whose Ar plasma-etching time was 90 min with optimum catalytic performance, exhibited a significant discrepancy between PMS activation and PDS activation. Interestingly, though the Ar-90-CNT/PDS system (kobs = 0.0332 min−1) was more efficient in SMX elimination than the Ar-90-CNT/PMS system (kobs = 0.0190 min−1), Ar plasma-etching treatment had no discernible enhancement in the catalytic efficiency of MWCNT for PDS activation. Then the discrepancy on activation mechanism between PMS and PDS was methodically investigated through quenching experiments, electron spin resonance (ESR), chemical probes, electrochemical measurements and theoretical calculations, and the findings unraveled that the created vacancy defects were the ruling active sites for the production of dominated singlet oxygen (1O2) in the Ar-90-CNT/PMS system to degrade SMX, while the electron transfer pathway (ETP), originated from PDS activation by the inherent edge defects, was the central pathway for SMX removal in the Ar-90-CNT/PDS system. Based on the toxicity test of Microcystis aeruginosa, the Ar-90-CNT/PDS system was more effective in alleviating environmental toxicity during SMX degradation. These findings not only provide insights into the discrepancy between PMS activation and PDS activation via carbon-based materials with controlled defects regulated by the plasma-etching strategy, but also efficiently degrade sulfonamide antibiotics and reduce the toxicity of their products.

Ball milling boosted hydrothermal N-doped sludge-derived biochar towards efficiently adsorptive removal of sulfamethoxazole from waters: Behavior, mechanism and DFT study

Developing an efficient adsorbent is of great significance to eliminate the adverse impacts on human and animals health caused by environmental concentration sulfamethoxazole (SMX). Various N-containing chemicals (ammonium chloride (NH4Cl), thiourea (CH4N2S), urea (CO(NH2)2), and melamine (C3H6N6)) were employed to activate sludge biochar (SBC) under hydrothermal condition. Afterward, the optimum hydrothermal N-doped SBC (NSBC-0.5) (C3H6N6 was confirmed as the perfect N-containing chemical) was further modified by ball milling to prepare BNSBC-0.5. The maximum adsorption capacity of BNSBC-0.5 for SMX calculated from Langmuir was 6.86 × 104 μg/g. The physicochemical properties analysis, adsorption experiments, together with density functional theory (DFT) calculation confirmed that the process of SMX adsorption onto BNSBC-0.5 was dominantly by Lewis acid-base, π-π conjugation, pore filling and electrostatic interactions. The multiple adsorption mechanism guaranteed the high anti-interference of BNSBC-0.5 to inorganic salts/strength and organic matter concentrations range and enabled it to be a promising adsorbent for efficiently eliminating SMX in various actual waters (Yangtze River water (88.5 %), lake water (89.3 %), running water (89.2 %), pure water (92.7 %), and deionized water (92.5 %)). The regenerated (via NaOH desorption) BNSBC-0.5 was capable of sustainably and effectively adsorbing SMX in recycles. Additionally, BNSBC-0.5 exhibited the satisfactory environmental safety in view of the low leaching levels of total nitrogen (TN) over a board pH range. This work synthesized a prospective adsorbent for SMX elimination, also the harmless disposal and waste utilization of sludge were accomplished.

Enhanced removal of sulfamethoxazole by Mn(II)/bisulfite in presence of nitrilotriacetic acid: Role of Mn(III)

Currently, the research on bisulfite (BS) activation by Mn(II) is very limited probably because of the low catalytic efficiency of Mn(II). Adding ligands to Mn(II)/BS system is likely to improve the BS activation, but the relative information is very rare. Therefore, the effect of nitrilotriacetic acid (NTA) on Mn(II)/BS system was investigated in this work using sulfamethoxazole (SMX) as the target contaminant. The results showed that the addition of NTA enhanced SMX removal in Mn(Ⅱ)/BS system through forming Mn(Ⅱ/III)-NTA complexes driving Mn(III)/Mn(II) cycle and stabilizing Mn(III). Alcohol scavenging experiments and competitive kinetic experiments indicated that sulfate radical (SO4•−) and hydroxyl radical (HO•) were not the main reactive species in Mn(II)/NTA/BS system. Mn(Ⅲ) was the primary oxidant for SMX elimination in this system and its existence was proved by UV-Vis absorption spectrum of reaction solution. Mn(Ⅱ)/NTA/BS system could greatly degrade SMX in near-neutral conditions, while nearly no SMX removal was observed at pH 3.0. The decrease of dissolved oxygen concentration significantly inhibited BS autocatalytic stage, thus suppressing the removal of SMX. Due to the competitive complexation of HCO3− and FA with NTA for Mn(II), their addition in Mn(Ⅱ)/NTA/BS system obviously inhibited SMX degradation. Four intermediates were detected during SMX degradation in Mn(Ⅱ)/NTA/BS system, and the possible SMX transformation pathways were speculated as N-S bond breaking, hydroxylation, amino oxidation and coupling reaction.

Catalytic wet air oxidation of sulfamethoxazole and tetracycline using platinum-based catalysts at eco-operating conditions

Conventional wastewater treatment plants (WWTP) are unsuitable for emerging contaminants' elimination. Most of these pollutants persist after the treatment and threaten the receiving environment. Catalytic wet air oxidation (CWAO) is one of the promising solutions to treat these concentrated active molecules. This study reports the catalytic degradation tests on sulfamethoxazole (SM) and tetracycline (TET) using platinum (Pt) supported on cerium oxide (Ce) and mixed cerium and zirconium oxides (CeZr). Pt/CeZr catalyst showed 98 % TET elimination at 50 °C under atmospheric pressure (Patm). Furthermore, the test at room conditions reached 92 % removal. Pt/Ce test enabled 77 % SM elimination and reached 45 % SM mineralization. Toxicity assessment confirmed the environmental legibility of the treated solution using CWAO. The outcomes of this study showed an eco-energetic, eco-friendly, and efficient way to treat wastewater loaded with pharmaceutical pollutants.

An in-situ electrogenerated persulfate and its activation by functionalized sludge biochar for efficient degradation of sulfamethoxazole

A novel oxidation system of in-situ electrogenerated persulfate (EO-PS) derived from sulphate in water and its activation by Fe/Mn bimetal co-functionalized sludge biochar (Fe/Mn-SBC) was built in this study to degrade sulfamethoxazole (SMX). The result showed that 98.8% of SMX was degraded within 60 min in EO/Fe/Mn-SBC/Na2SO4 system. The abundant defect structures, oxygen-containing functional groups, Mn(Ⅱ)/Mn(Ⅲ) and magnetic Fe3O4 on Fe/Mn-SBC surface guaranteed its outstanding activation performance for EO-PS. The quenching and electron paramagnetic resonance (EPR) experiments confirmed that non-radicals of 1O2 and surface-bound radicals were the dominant contributors for SMX elimination. The pathway Ⅰ and Ⅲ were proposed to be the main pathways of SMX degradation in EO/Fe/Mn-SBC/Na2SO4 system based on its transformed products (TPs) identification and density functional theory (DFT) calculation. Overall, the TPs of SMX generated in EO/Fe/Mn-SBC/Na2SO4 system were less toxic to aquatic organisms compared to that of SMX. Also, EO/Fe/Mn-SBC/Na2SO4 system displayed favorable degradation performance for SMX in real waters (98.5%, 91.1%, 84.8%, 81.2% and 77.4% in pure water, tap water, river water, lake water and sewage effluent, respectively). Additionally, Fe/Mn-SBC exhibited the easy magnetic separation, excellent reusability and environmental safety. This study developed a promising technology of in-situ EO-PS and its activation by carbon-based material for SMX elimination without addition of exogenous PS, in addition to that the resource utilization of sewage sludge and wastewater sulphate were simultaneously achieved.

Heterogeneous Activation of Persulfate by Nickel Oxide/Strontium Carbonate Composite for Sulfamethoxazole Degradation in Water

The development of efficient heterogeneous persulfate activators is one of the main research topics in the wastewater treatment area. The present work deals with the heterogeneous activation of sodium persulfate (SPS) using nickel oxide/strontium carbonate (NiO/SrCO3) for the degradation of sulfamethoxazole (SMX), a representative compound from the group of antibiotics. Results showed that NiO/SrCO3 exhibited high performance towards the activation of SPS, leading to SMX elimination in brief time spans. The impact of SPS (25–100 mg/L), NiO/SrCO3 (50–250 mg/L), and SMX (0.25–3.00 mg/L) concentration, and initial pH on the decomposition of SMX was further examined. Experiments were also conducted in real matrices such as secondary effluent and bottled water, revealing the existence of retarding phenomena compared to ultrapure water. This behavior was further investigated with the addition of bicarbonates, chlorides, or humic acid in ultrapure water. It was found that organic matter significantly hampered SMX removal. The role of the main radicals (hydroxyl and sulfate radicals) was determined using appropriate radical traps (methanol and tert-butanol). These quenching experiments combined with the conducted electrochemical measurements revealed that both a radical and a non-radical mechanism contribute to the decomposition of SMX.

Selective removal of sulfamethoxazole by a novel double Z-scheme photocatalyst: Preferential recognition and degradation mechanism

Sulfamethoxazole (SMX) is a significant environmental concern due to its adverse effects and ecological risks. SMX elimination in aquatic environments via photocatalysis presents a viable solution, given its high oxidation potential. However, such a solution remains controversial, primarily due to a lack of selectivity. Here we introduce a molecularly imprinted TiO2@Fe2O3@g-C3N4 (MFTC) photocatalyst designed for the selective degradation of SMX. To assess MFTC's selectivity, we applied it to degrade synthetic wastewater containing SMX alongside interfering species sulfadiazine (SDZ), ibuprofen (IBU), and bisphenol A (BPA). The results demonstrated a selective degradation efficiency rate of 96.8%, nearly twice that of competing pollutants. The molecularly imprinted sites within the catalyst played a crucial role by selectively capturing SMX and enhancing its adsorption, thereby improving catalytic efficiency. The degradation process involved •OH and •O2− free radicals, with a newly proposed double Z-scheme mechanism and potential pathway for SMX degradation by the MFTC photocatalytic system. This study enriches the application of photocatalysis using molecularly imprinted nanocomposite materials for treating complex pollutant mixtures in water.

FeCu-coal gangue heterogeneous activation of peracetic acid for degradation of sulfamethoxazole

A novel FeCu anchored coal gangue (FeCu-CG) composite was prepared by a two-step (acidation and subsequent chemical reduction) method and applied in catalytic activation of peracetic acid (PAA) for sulfamethoxazole (SMX) removal in water. The BET, XPS, SEM, EDS, and XRD characterization of FeCu-CG indicated that it had a porous structure with the SBET area of 36.38 m² g−1 and nano-FeCu particles were successfully loaded in the CG carrier, which provided electrons and Fe(II) for PAA decomposition through the bimetallic corrosion reaction. The hydroxyl radical (HO•) was verified to be largely responsible for SMX elimination in FeCu-CG/PAA system. More than 96.4 % of SMX was removed by FeCu-CG/PAA in 40 min at initial pH ranging from 5.0 to 9.0. Increasing FeCu-CG dosage from 0.1 to 1.0 g L−1 could enhance SMX degradation in FeCu-CG/PAA system, but higher dosage inhibited SMX removal owing to the aggregation of FeCu-CG particles. Coexisting dissolved organic matter (DOM), HCO3- and Cl- suppressed SMX degradation. The degradation pathways of SMX by FeCu-CG/PAA were proffered including hydroxylation, amino oxidation, bond cleavage and coupling reaction based on five detected degradation products.

Nitrogen-doped carbon materials prepared using different organic precursors as catalysts of peroxymonosulfate to degrade sulfamethoxazole: First-time performance leading to the incorrect selection of the best catalyst

Nitrogen-doped carbon materials are effective catalysts for peroxymonosulfate (PMS) activation to eliminate organic contaminants. In this research, the activity of nitrogen-doped carbon materials was significantly improved by optimizing the carbon source, and the reusability of the catalyst is used to select the best catalyst instead of depending on the performance in the first use, for avoiding the “short-life” catalyst with great initial activity. Fixing ferric nitrate nonahydrate and melamine as the metal and nitrogen sources, four catalysts were prepared using glucose, glucosamine hydrochloride, dopamine, and trimesic acid as the carbon sources, respectively. Based on the performance in PMS activation for sulfamethoxazole (SMX) removal, in the first use, the activity was Fe-DA-CN (carbon source: dopamine) > Fe-BTC-CN (carbon source: trimesic acid) > Fe-GLU-CN (carbon source: glucosamine) > Fe-DGLU-CN (carbon source: glucose). With no washing for the second time use, the activity was Fe-BTC-CN (0.135 min−1) ≫ Fe-DA-CN (0.037 min−1) > Fe-GLU-CN (0.032 min−1) > Fe-DGLU-CN (0.017 min−1). The large specific surface area, superior graphitization, and high CO/C–N group content endow Fe-BTC-CN with high ability in PMS activity. Surface-bound radicals are responsible for SMX elimination, and most of the SMX degradation intermediates have lower ecotoxicity than SMX.

Metabolic Disposition and Elimination of Tritum-Labeled Sulfamethoxazole in Pigs, Chickens and Rats.

Sulfamethoxazole (SMZ), as a sulfa antibiotic, is often used in the treatment of various infectious diseases in animal husbandry. At present, SMZ still has many unresolved problems in the material balance, metabolic pathways, and residual target tissues in food animals. Therefore, in order to solve these problems, the metabolism, distribution, and elimination of SMZ is investigated in pigs, chickens, and rats by radioactive tracing methods, and the residue marker and target tissue of SMZ in food animals were determined, providing a reliable basis for food safety. After a single administration of [3H]-SMZ (rats and pigs by intramuscular injection and chickens by oral gavage), the total radioactivity was rapidly excreted, with more than 93% of the dose excreted within 14 days in the three species. Pigs and rats had more than 75% of the administered volume recovered by urine. After 7 days of continuous administration, within the first 6 h, radioactivity was found in almost all tissues. The highest radioactivity and longest persistence in pigs was in the liver, while in chickens it was in the liver and kidneys, most of which was removed within 14 days. A total of six, three and three metabolites were found in chickens, rats and pigs, respectively. N4-acetyl-sulfamethoxazole (S1) was the main metabolite of SMZ in rats, pigs and chickens. The radioactive substance with the longest elimination half-life is sulfamethoxazole (S0), so S0 was suggested to be the marker residue in pigs and chickens.

Converting Hybrid Mechanisms to Electron Transfer Mechanism by Increasing Biochar Pyrolysis Temperature for the Degradation of Sulfamethoxazole in a Sludge Biochar/Periodate System

In this study, sludge biochar was prepared under four pyrolysis temperatures (SBC300, SBC500, SBC700, and SBC900) and then was employed to activate periodate (PI) for the degradation of sulfamethoxazole (SMX). Various characterization methods were employed to investigate the effect of pyrolysis temperature on the physicochemical properties of sludge biochar and the activation capacity of periodate. The SMX adsorption capacity of SBCs and the ability of activating PI to degrade SMX increased with the increasing pyrolysis temperature. The degradation of SMX by the SBCs/PI systems was highly dependent on the initial pH of the solution and the dosage of SBCs. Mechanistic studies indicated that the degradation of SMX by the SBCs/PI system was mainly based on an electron-mediated transfer mechanism. Additionally, the electron transfer capacity of the SBCs affected the defects and the degree of graphitization. The contribution of free radicals to SMX degradation decreases with increasing pyrolysis temperature. Toxicity experiments demonstrated that the toxic elimination of SMX by the SBCs/PI system was enhanced with increasing pyrolysis temperature.

Peroxymonosulfate activation via CoP nanoparticles confined in nitrogen-doped porous carbon for enhanced degradation of sulfamethoxazole in wastewater with high salinity

Transition-metal phosphides (TMPs) have been considered a promising candidate for heterogeneous catalysis in wastewater treatment, while the feasibility of its application in peroxymonosulfate (PMS) based advanced oxidation processes systems for the treatment of high-salinity organic wastewater remains still unclear. In this study, catalysts of cobalt phosphide (CoP) nanoparticles confined in nitrogen-doped porous carbon (CoP/NC) were prepared using zeolitic imidazolate framework-67 (ZIF-67) as a template via calcination-oxidation-phosphorization, which were subsequently applied to activate peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX) in the water with high-salinity concentrations. Results showed that the degrading performance of CoP/NC could be improved and regulated by phosphorus (P) doping amount with an optimum of 5.0% (CoP/NC-5), which reached 100% of SMX degradation. Meanwhile, CoP/NC-5 catalyst could tolerate wide pH variations (5–9). More importantly, the CoP/NC-5/PMS system showed high adaptability to various concentrations of inorganic salt, even up to 500 mM. In addition, active species of sulfate radical (SO4•−) and singlet oxygen (1O2) were identified, which played dominant roles in the destruction of SMX, and the production amount of SO4•− was quantified. This work confirmed that transition-metal phosphides nanoparticles confined in nitrogen-doped porous carbon were a promising catalyst for SMX elimination in high saline wastewater.

Molybdenum co-catalytic promotion for Fe3+/peroxydisulfate process: performance, mechanism, and immobilization

In this work, we proposed that molybdenum (Mo) powder as the cocatalyst could promote the sulfamethoxazole (SMX) decomposition in the Fe3+/peroxydisulfate (PDS) Fenton-like process. Efficient SMX elimination (96.7%) was reached after 20 min under the circumstances of 0.20 g·L−1 Mo, 0.50 g·L−1 PDS, 0.07 g·L−1 Fe3+, and beginning pH 5.4. Sulfate radicals were verified as the main active species according to the quenching experiment and electron spin resonance spectroscopy analysis. The Mo cocatalyst improved the Fe3+ reduction and PDS activation. According to the investigation of X-ray photoelectron spectroscopy for the valence state change of Mo before and after the reaction, the mechanism of Fe3+/Fe2+ circulation being initiated through the Mo4+ and Mo0 was presented. There was no obvious change of surface structure between the original and used Mo, as certified through X-ray diffraction and scanning electron microscope analyses. The mass spectrometry was used to determine the SMX degradation byproducts, and their toxicities were evaluated by the computational toxicology. Importantly, even after five cycles, the Mo still displayed excellent recyclability, and above 93% SMX was degraded in the fifth recycle. In the end, the immobilization of Mo was attempted by fixing Mo on the cyanoacrylate and agar, which also both showed the good co-catalytic effect. This research affords a promising inorganic co-catalytic Fenton-like system for water treatment.