Degradation Of Sulfadiazine Research Articles

Facilitated Visible-Light-Driven Peroxymonosulfate Activation by a Co-Fe Layered Double Hydroxide Derived p-n Heterostructure for Sulfadiazine Degradation: Affecting Parameters, Kinetics, and Mechanistic Insights.

The utilization of multivalence ionic metal species generated through a peroxymonosulfate (PMS)-assisted photocatalytic system is a promising platform for the selective degradation of water contaminants. However, achieving an effective electron transport and enhanced separation efficiency for these metal species is a daunting challenge. Thus, our current study addresses this challenge by using a Co-Fe-based layered-double-hydroxide template to synthesize a Co3O4/FeCo2O4 p-n heterojunction composite via a simple monosynthetic route. The resultant composite is thoroughly validated through advanced characterization techniques that efficiently activate PMS for sulfadiazine (SDZ) degradation under visible light, achieving a remarkable degradation efficiency of up to 90%. This accomplishment is attributed to factors including intimate interfacial contact, excellent light harvesting, mesoporosity, and oxygen vacancies within the composite. The formation of a distinct p-n heterojunction following the S-scheme charge dynamic significantly enhances photogenerated carrier separation and reduces charge recombination. The research delves into comprehensive investigations including degradation studies, active species trapping experiments, parameter exploration, and in-depth liquid chromatography-mass spectrometry for analysis of the degradation byproducts and pathway. Induced oxygen vacancies, strategically placed active surface sites, and mesoporosity in the Co3O4/FeCo2O4 composite synergistically boosted the sluggish PMS activation, leading to enhanced SDZ degradation. This study introduces a new perspective by demonstrating the potential of a single-material, mixed-metal oxide-based p-n heterojunction photocatalytic system following the S-scheme charge-transfer route for SDZ degradation. The findings contribute toward emphasizing the importance of tailored composite materials in tackling persistent contaminants.

Peroxymonosulfate activation by cobalt-doped ferromanganese magnetic oxides through singlet oxygen and radical pathways for efficient sulfadiazine degradation.

In this paper, cobalt-doped MnFe2O4 (CMFO-0.4) with oxygen vacancies was successfully synthesised by the sol-gel method and applied as a high-performance catalyst for the activation of peroxomonosulfate (PMS). The catalyst showed an excellent catalytic effect for the degradation of sulfadiazine (SDZ) by activated PMS, and the degradation rate can reach 100% in 10 minutes. The effects of different conditions on the degradation of SDZ were investigated, and it was determined that the optimal concentrations of catalyst and PMS were 0.2 g L-1 and 1 mM, respectively, and had good degradation effects in the pH 5-11 range. Free radical quenching experiments, XPS, and electron paramagnetic resonance (EPR) analyses revealed the presence of hydroxyl radicals (˙OH), sulphate radicals (SO4˙-), singlet oxygen (1O2), and superoxide radicals (˙O2 -) in the CMFO-0.4/PMS system, with 1O2 being the main reactive oxygen species (ROS). In addition, CMFO-0.4 has good reusability and adaptability to the presence of other substances.

Co@MoS2 Nanocatalyst: Enhanced Activation of Peroxymonosulfate for Effective Degradation of Sulfadiazine

To improve the activation efficiency of PMS to efficiently degrade antibiotic sulfadiazine (SD), herein, a Co@MoS2 catalyst was prepared by a one-step hydrothermal process. The unique petal-like structure of MoS2 enables the transition metal Co to achieve high dispersion and avoid agglomeration. Mo(IV) and unsaturated S accelerate the electron transfer between Co[Formula: see text] and Co[Formula: see text] to improve the cycling efficiency and thus realize the efficient activation of PMS. The results of active substance quenching experiment and ESR analysis show that the main active substance for the efficient degradation of SD by Co@MoS2 is the non-radical 1O2, while the other three radicals [Formula: see text], ⋅OH and [Formula: see text] contribute significantly to the efficient degradation of SD. And after 5 cycles, the degradation could still be as high as 90%. The strong consolidation of Co on the petal-shaped sheet of MoS2 ensures the stability of Co@MoS2 catalyst.

Simulated solar-driven photo-assisted anodic oxidation of sulfadiazine by C3N4 modified Ti3+ self-doping TiO2 nanotube arrays

In this study, a C3N4 modified Ti3+ self-doping TiO2 nanotube arrays (C3N4-Ti3+/TiO2-NTA) material was innovatively fabricated using a three-step procedure consisting of anodization, chemical vapor deposition, and in-situ cathodic polarization. Simultaneously introducing C3N4 and Ti3+ significantly enhanced the light absorption property and charge separation efficiency of TiO2-NTA, while also increasing the oxygen evolution overpotential to 2.61 V vs the silver/silver chloride electrode. C3N4-Ti3+/TiO2-NTA with excellent optoelectronic properties was first applied as an anode in the simulated solar-driven photo-assisted anodic oxidation (PAO) system. It was found that the PAO system for the degradation of sulfadiazine (SDZ) exhibited 12.1-fold and 1.9-fold higher activity compared to the photocatalytic system and the anodic oxidation system alone, respectively, indicating the optoelectronic synergistic interactions over C3N4-Ti3+/TiO2-NTA. Quenching experiments and electron spin resonance results suggested that main reactive species during the degradation of SDZ by the PAO system were hydroxyl radical and superoxide radical. Additionally, three possible degradation pathways of SDZ by the PAO were proposed based on the identification of intermediate byproducts and theoretical calculation. Furthermore, the biosafety evaluation revealed a significant reduction in the biological toxicity of intermediate byproducts of SDZ. These findings provide new insights into the design and manufacturing of novel anode material for efficient degradation of recalcitrant pollutants in practical applications under solar irradiation.

Recycling different crystal forms of MnO2 from spent Li-ion batteries cathodes for SDZ degradation

Environmental pollution due to antibiotics usage and spent Li-ion batteries is escalating. To solve this issue, MnO2 with different crystalline phases were prepared as catalysts (recovered from spent lithium-ion battery cathode materials) for the degradation of sulfadiazine (SDZ) in this study by acid leaching and hydrothermal methods, respectively. The morphological and structural characteristics of catalysts were examined by XRD, SEM, XPS, and BET. The catalyst MnO2-6 h (β-MnO2) synthesized in six hours by hydrothermal method showed higher performance in destroying SDZ compared to MnO2-3 h (λ-MnO2) obtained by acid leaching method. Over 95% of SDZ was degraded by 0.2 g/L MnO2-6 h, 1 mM peroxymonosulfate (PMS) at pH 6 by pseudo-first-order kinetics. Density Functional Theory (DFT) calculations and related experimental analyses revealed that the main ROS within the MnO2-6 h/PMS system is SO4－·, which contributes about 67.49% to the degradation of SDZ. The high crystallinity and high Mn(III) ratio of MnO2-6 h are the key to the high catalytic activity of MnO2-6 h, which is highly stable and has potential for practical wastewater treatment. The study provides a new approach to managing the solid waste of spent Li-ion batteries and controlling emerging pollutants resulting from heavy antibiotic use.

Construction of a myoglobin scaffold-based biocatalyst for the biodegradation of sulfadiazine and sulfathiazole

Sulfonamide antibiotics, a family of broad-spectrum antibiotic drugs, are increasingly used in aquaculture and are frequently detected in aquatic environments. This poses a potential threat to organisms and may cause the evolution of antimicrobial resistance. Therefore, it is important to develop an environmentally friendly and efficient biocatalyst to degrade sulfonamides (SAs) such as sulfadiazine (SD) and sulfathiazole (ST). Here, we realized the direct and efficient degradation of SD and ST using a hydrogen peroxide-dependent artificial catalytic system based on myoglobin (Mb). The arrangements of amino acids at positions 29, 43, 64, and 68 were found to influence catalytic activity. An L29H/H64D/V68I myoglobin mutant showed the best catalytic efficiency (i.e., kcat/Km = 720.42 M−1 s−1) against SD. Next, mutant H64D/V68I showed the best degradation rate against SD (i.e., 91.45 ± 0.16%). Moreover, L29H/H64D/V68I Mb was found to efficiently catalyze ST oxidation (kcat/Km = 670.08 M−1 s−1), while H64D/V68I had the best degradation rate against ST (i.e., 99.45 ± 0.23%). Our results demonstrate that SAs can be efficiently degraded by artificial peroxygenases constructed using a myoglobin scaffold. This therefore provides a simple and economical method for the biodegradation of SD and ST.

Accelerated removal of sulfadiazine by heterogeneous electro-Fenton system with Pt-FeOX/graphene single-atom alloy cathodes

Heterogeneous electro-Fenton (EF) process is emerging as an attractive treatment technology for removal of sulfadiazine (SDZ), in which in situ generation of H2O2 and Fe(II) are crucial steps. In this study, Pt-FeOX/G was synthesized as a heterogeneous EF catalyst by incorporating Pt single atoms into a FeOX nanocrystal. The optimized Pt1-FeOX/G cathode exhibited an SDZ conversion of >90% within 30 min over a broad pH range (3–11). The Pt1-FeOX/G cathode under a strong alkaline medium exhibited very prominent selectivity to H2O2 via 2e− oxygen reduction reaction with a maximum H2O2 concentration of 211.93 mg L−1. The hydroxyl radicals in the cathodic chamber were mainly derived from the in situ conversion of generated H2O2 in the heterogeneous EF system. The structure-activity results of Pt-FeOX/G suggested that the SDZ removal efficiency was closely related to the decentralized morphology and electronic configuration of the Pt-FeOX microcrystalline structure. Three possible SDZ degradation pathways, dominated by S–N bond cleavage, were proposed based on the stage products. The toxicity of the major products was determined using the ecological structure-activity relationship model in conjunction with trophic aquatic organisms. This study demonstrated the feasibility of enhancing heterogeneous EF catalysis for antibiotic-polluted water using multifunctional single-atom alloy cathodes.

Polydopamine-modified magnetic foam composites synergistically activate peroxymonosulfate with visible light for sulfadiazine degradation and oil–water separation

This study used a CuSO4/H2O2 catalyst to accelerate the oxidation and polymerization of dopamine in solution to facilitate the rapid deposition of polydopamine (PDA) onto a melamine foam. Dopamine provided the Fe3O4 adhesive layer and additional photocatalytic electron transfer channels for the foam. Stearic acid (SA) was used as the final incorporation on the surface of melamine foam(MF) to further superhydrophobically modify the magnetic foam (MF@PDA/Fe3O4) to obtain superhydrophobic magnetic MF@PDA/Fe3O4@SA foam. The foam has excellent capacity, acid resistance, alkali resistance, flame retardant, and salt resistance and can be conveniently separated, recycled, and recovered using magnetism. At the same time, peroxymonosulfate (PMS) can be activated to generate super-active radicals. Within 16 min, the degradation rate of sulfadiazine (SDZ) reached 99.8 %. Trapping experiments and EPR analysis confirmed the critical roles of ·OH, ·SO4− and 1O2 in SDZ removal. The wide pH working range (1.0 ∼ 13.0) and the slight toxicity of photocatalytic intermediates indicate that the as-prepared MF@PDA/Fe3O4@SA/PMS system has good application potential. The foam has potential practical applications in emergency oil spill rescue and oil/organic solvent wastewater treatment. Furthermore, this study provides a promising strategy for designing and fabricating a novel magnetic foam and photoactivated PMS synergistic system to eliminate pharmaceutical antibiotics effectively.

Electron transfer-mediated enhancement of superoxide radical generation in fenton-like process: Key role of oxygen vacancy-regulated local electron density of cobalt sites

Designing metal oxides with oxygen vacancy (OV) is a prospective strategy for boosted Fenton-like process. However, what OV is, whether OV enhancement increases the catalytic performance, OV-related H2O2 activation, and relationship between OV and ROS or non-radical pathways have not been fully understood. Herein, yolk-shell Co3O4 nanospheres with various OV were fabricated to overcome the above contentious problems and establish a relationship between OV, ROS, and electron transfer in sulfadiazine (SDZ) degradation via H2O2 activation. The results showed that the delocalized electron-rich Co sites around OV with increasing OV allowed the improved conductivity, thereby leading to stronger adsorption and activation of H2O2 to generate more •OH as evidenced by the attenuated adsorption energy and prolonged O-O bond. The subsequent rapid depletion of •OH coupled with the increase in O2•− over time and the emergence of electron transfer from SDZ explored a pathway enhancing O2•− generation for SDZ degradation.

Oxygen vacancies promoted the generation of sulfate radicals and singlet oxygen by peroxymonosulfate activation with Co3O4 quantum dots/g-C3N4 nanosheets

Co3O4 quantum dots /g-C3N4 nanosheets nanomaterials with vacancies (VO-CoCN) were fabricated by deposition–precipitation and NaBH4 reduction. TEM and HRTEM images indicated that Co3O4 particles of about 2 nm size are uniformly distributed on the surface of the g-C3N4 nanosheets. Furthermore, the formation of oxygen vacancies was also confirmed by HRTEM, XPS, ESR and other techniques. The 0.25-VO-CoCN catalyst coupled with peroxymonosulfate (PMS) exhibits excellent sulfadiazine (SDz) removal efficiency is up to 100 % in 20 min, with a mineralization rate of 77.4 %. The cycle stability of the 0.25-VO-CoCN catalyst was also significantly improved compared to CoCN samples without vacancies for PMS activation. Moreover, the 0.25-VO-CoCN/PMS system can maintain the efficient SDz removal rate in the presence of low-concentration inorganic anions (NO3–, HCO3– and Cl-) in the pH range of 5–9. The free radical quenching experiment and EPR characterization reveal that the •SO4- radicals and 1O2 non-free radicals are the main reactive oxygen species of SDz degradation in the VO-CoCN/PMS system. The superior degradation performance is attributed to the fact that oxygen vacancies can promote the redox cycling of Co3+/Co2+, thereby increasing the formation of •SO4- and simultaneously promoting the formation of singlet oxygen species.

Performance of a recirculated biogas-sparging anaerobic membrane bioreactor system for treating synthetic swine wastewater containing sulfadiazine antibiotic

Anaerobic Membrane Bioreactor (AnMBR) is an efficient system for treating synthetic swine wastewater (SW). However, the presence of antibiotics in SW discourages the activity of microorganisms, resulting in less pollutants removal and biogas production. In this paper, a recirculated biogas-sparging anaerobic membrane bioreactor system was used to treat swine wastewater containing sulfadiazine (SDZ). The effects of different concentrations of SDZ on the AnMBR system’s performance were explored, in terms of pollutant removal, biogas production, membrane fouling and microbial community. Results indicated that the larger concentration of SDZ triggered a strong suppression in the system’s performance. When treating 1.0 mg/L SDZ, the biogas-sparging AnMBR system achieved about 77 % COD removal and 0.23 L/g CODremoved biogas production, which without SDZ fell to 21 % COD being removed and dropped biogas production by 30 %. As well, the presence of SDZ (1.0 mg L) increased by about half the amount of soluble microbial product (SMP) and extracellular polymeric substances (EPS) with lower protein/polysaccharide ratio and reduced sludge particle size by 49 %. Meanwhile, microbial community analysis revealed that the abundance of Firmicutes increased while Chloroflexi diminished. These jointly contributed to a shorter membrane fouling cycle declining from the initial 23 d to 7 d. Furthermore, the shift from acetoclastic methanogens to hydrogenotrophic methanogens resulted in less methane production due to the presence of SDZ, while the hydrogenotrophic methanogen Methanobacterium promoted the degradation of SDZ. The work showed AnMBR can effectively treat swine wastewater containing antibiotics and provides basis for practical application.

A novel immobilized horseradish peroxidase platform driven by visible light for the complete mineralization of sulfadiazine in water

A novel immobilized enzyme driven by visible light was prepared and used for complete mineralization of antibiotics in water bodies. The immobilized enzyme was composed of carbon nitride modified by biochar (C/CN) and horseradish peroxidase (HRP), establishing the photo-enzyme coupling system with synergistic effect. Among them, the introduction of biochar not only improves the stability and loading capacity of the enzyme, but also improves the light absorption capacity and carrier separation efficiency of the photocatalyst. After the optimization of immobilization process, the solid load of HRP could reach 251.03 mg/g, and 85.03 % enzyme activity was retained after 18 days of storage at 4 °C. In the sulfadiazine (SDZ) degradation experiment, the degradation rate of HRP/C3/CN reached 71.21 % within 60 min, which was much higher than that of HRP (2.33 %), CN (49.78 %) and C3/CN (58.85 %). In addition, under the degradation of HRP/C/CN, the total organic carbon (TOC) removal rate of SDZ reached 53.14 %, which was 6.47 and 1.74 times that of CN and C3/CN, respectively. This study shows that the introduction of biochar is of great significance to the photo-enzyme cascade coupling system and provides a new strategy for the application of HRP&g-C3N4 system in wastewater treatment.

Efficient degradation of sulfadiazine by photosynthetic cyanobacteria Synechocystis sp. PCC 6803 coupling with recombinant laccase strategy

Efficient degradation of sulfadiazine by photosynthetic cyanobacteria Synechocystis sp. PCC 6803 coupling with recombinant laccase strategy

Sulfadiazine removal efficiency with persulfate driven by electron-rich Cu-beta zeolites

Surface electron transport and transfer of catalysts have important consequences for persulfate (PS) activation in PS system. In this paper, an electron-rich Cu-beta zeolites catalyst was synthesized utilizing a straightforward solid-state ion exchange technique to efficiently degrade sulfadiazine. The X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) results revealed that Cu element substitutes Al element and enters the beta molecular sieve framework smoothly. Furthermore, the X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the Cu-beta catalyst is primarily Cu0. Cu-beta zeolites catalyst can exhibit excellent catalytic activity to degrade sulfadiazine with the oxidant of PS. The optimal sulfadiazine removal performance was explored by adjusting reaction parameters, including sulfadiazine concentration, catalyst dosage, oxidant dosage, and solution pH. The sulfadiazine removal efficiency in the Cu-beta zeolites/PS system could reach 90.5% at the optimal reaction condition ([PS]0 = 0.5 g/L, [Cu-beta zeolites]0 = 1.0 g/L, pH = 7.0) with 50 mg/L of sulfadiazine. Meanwhile, The degradation efficiency was less affected by anionic interference (Cl−, SO4−, HCO3−). The surface electron transport and transfer of the Cu-beta zeolites catalyst were significant causes for the remarkable degradation performance. According to electron paramagnetic resonance (EPR) and quenching studies, the Cu-beta zeolites/PS system was mostly dominated by SO4•- in the degradation of sulfadiazine. Furthermore, two possible pathways for sulfadiazine degradation were proposed according to the analysis of intermediate products detected by the liquid chromatography–mass spectrometry (LC-MS).

A novel DBD/VUV/PMS process for efficient sulfadiazine degradation in wastewater: Singlet oxygen-dominated nonradical oxidation

In this study, a novel process of dielectric barrier discharge plasma/vacuum ultraviolet/peroxymonosulfate (DBD/VUV/PMS) for the nonradical-dominated degradation of sulfadiazine (SDZ) was investigated. The hybrid system has significant synergistic effects, with 95.5% SDZ and 68.3% TOC removal within 10 min. The activation efficiency of DBD/VUV (69.0%) on PMS via multipath was 2.07 times higher than that of single DBD (33.3%) under alkaline conditions. Electron paramagnetic resonance analyses and trapping experiments showed 1O2 was the primary active substance in the DBD/VUV/PMS process. The predominant role of 1O2 revealed that SDZ removal mainly followed the nonradical reaction pathway, contrary to the previously reported non-thermal plasma (NTP)-based radical-dominated process. Multiple spectroscopy analysis showed the efficient degradation process of SDZ. Unlike the radical attack sites, the SDZ transformation pathway by nonradical 1O2 was probably initiated by an aniline ring site attack based on density functional theory (DFT) calculations and product analyses. The DBD/VUV/PMS process reduced energy consumption by 69% compared to DBD. Finally, the evaluation of ecotoxicity and PMS utilization demonstrated the advantages and application prospects of the DBD/VUV/PMS process. This research developed a new nonradical-dominated pathway for antibiotic degradation by the photo/plasma/persulfate process.

NEW METHOD OF SULFADIAZINE RESIDUE BIODEGRADATION IN POULTRY MANURE BY SPORE-BOUNDING LACCASE

Antibiotics have been used in livestock farming worldwide. In poultry farming, sulfonamide antibiotics are mainly used to inhibit microbial infection. Sulfadiazine (SDZ) is one type of sulfonamide that is secreted into the ecosystem through feces and urine owing to its low adsorption and degradation in the animal intestine. In this study, the spore-bound laccase from the Bacillus sp. strains was investigated for its potential for degradation of SDZ. The highest laccase activity was selected to degrade the SDZ residue in the poultry feces. The results demonstrated that the spore-bound laccase of Bacillus sp. PM45 successfully reduced the residue of SDZ in poultry manure by 98.00±0.50 %. This work gained new knowledge and the method is cost-effective and more eco-friendly for antibiotic residue treatment.

The enhanced peroxydisulfate activation performance of nitrogen doped biochar encapsulating cobalt in three-dimensional electrochemical system for sulfadiazine removal and mechanism

To boost the peroxydisulfate (PDS) activation performance of biochar (BC) encapsulating cobalt (Co@RBC) in the three-dimensional (3D) electrochemical system, serials N-doped BC encapsulating cobalt (Co@RBC-xN) was prepared using urea as N sourcing and rose petals as biomaterials in this work. Results revealed that N doping can largely promote the PDS activation performance of Co@RBC toward sulfadiazine (SD) degradation in the 3D electrochemical system. The structure-activity relationship analysis revealed that Co0 and sp2-C/sp3-C in catalysts promoted by the doped pyridinic N benefited in strengthening PDS utilization on catalysts surface, thus largely boosting PDS activation efficiency for SD degradation in the system even with a low PDS dosage (0.5 mM). And pyridine N and Co0 were main active sites for PDS activation. Integrating with reactive species trapping experiments and electron paramagnetic resonance (EPR), it revealed that singlet oxygen (1O2), superoxide radical (•O2−) and surface-bounded radicals made main contribution to SD degradation. In addition, the as-prepared Co@RBC-3 N exhibited excellent and stable catalytic activity, good anti-interference of natural water matrices, and easily magnetic separation from solution. This study developed an effective, stable and easily recovery catalysts for PDS activation in 3D electrochemical system and promoted the application possibility of this system for antibiotics removal from wastewater.

Synergistic effects of layered Ti3C2TX MXene/MIL-101(Cr) heterostructure as a sonocatalyst for efficient degradation of sulfadiazine and acetaminophen in water

In this work, different mass loadings of MXene-coupled MIL-101(Cr) (MXe/MIL-101(Cr)) nanocomposites were generated through a hydrothermal process in order to investigate the potential of this nanocomposite as a novel sonocatalyst for the elimination of sulfadiazine (SD) and acetaminophen (AAP) in aqueous media. The sonocatalytic activity of different MXe/MIL-101(Cr) compositions and surface functionalities was investigated. In addition, the sonocatalytic activities at various pH values, temperatures, pollutant concentrations, catalyst dosages, initial H2O2 concentrations, and organic matter contents were investigated. The experiments on the sonocatalytic elimination of SD and AAP revealed that MXe/MIL-101(Cr) exhibited a catalytic efficiency of ∼ 98% in 80 min when the MXene loading was 30 wt% in the nanocomposite. Under optimized reaction conditions, the degradation efficiency of MXe/MIL-101(Cr) reached 91.5% for SD and 90.6% for AAP in 60 min; these values were 1.2 and 1.8 times greater than those of MXene and MIL-101(Cr), respectively. The high surface area of the MXe/MIL-101(Cr) nanocomposite increased from 4.68 m2/g to 294.21 m2/g, and the band gap of the tagged MIL-101(Cr) on the MXene surface was minimized. The superior sonocatalytic activity of MXe/MIL-101(Cr) was attributed to the effective contact interface, the effective separation rate of e- − h+ pairs through the type II heterostructure interface, and the favorable high free •OH radical production rates that promoted the degradation of SD and AAP. The solid heterointerface between MIL-101(Cr) and MXene was confirmed through Raman and FTIR analysis and was found to promote accessible •OH radical production under sonication, thus maximizing the catalytic activity of nanocomposites. The present results present an effective strategy for the design of a highly efficient, low-cost, reliable sonocatalyst that can eradicate pharmaceutical pollutants in our environment.

Ball milling enhanced magnetic corn straw biochar for peroxyacetic acid activation towards efficient degradation of sulfadiazine

A novel heterogeneous catalyst of ball-milling magnetic corn straw biochar (BMCBC) was the first time synthesized and employed to activate peroxyacetic acid (PAA) for efficiently degrading sulfadiazine (SDZ). The superior porous structure and the magnetic Fe3O4 of BMCBC guaranteed its higher activation efficiency than that of CBC. The results showed that 93% of SDZ was removed by PAA/BMCBC system within 60 min. Solution pH, CO32-, NO3- and Cl- concentrations were the crucial environmental factors affecting the degradation process of SDZ. The electron paramagnetic resonance (EPR), quenching experiments, and Raman spectra analysis indicated that •OH and R-O• were the main contributors to SDZ degradation. The transformed products (TPs) generated in PAA/BMCBC system were less toxic compared to those of SDZ. Three degradation pathways of SDZ were proposed and hydroxylation and S-N bond breakage by •OH and R-O• attacking were the dominant degradation pathways of SDZ in PAA/BMCBC system. Also, PAA/BMCBC system built in this study exhibited excellent removal performance for SDZ in actual waters including river water (84.32%), lake water (73.95%), tap water (93.30%) and drinking water (91.29%). Additionally, BMCBC exhibited satisfactory environmental safety in a wide pH range (from 3 to 11) with low leaching levels of Fe. The good magnetic sensitivity of BMCBC enabled it to be easily collected and it performed outstanding sustainable activation performance for PAA even after five reuse cycles. This study developed a promising method for antibiotics (e.g., SDZ) elimination, in addition to that the resource utilization of agricultural wastes (e.g., corn straw) was achieved.

Natural tourmaline activated peracetic acid for efficient degradation of sulfadiazine: Reaction mechanisms and catalyst reusability

Peracetic acid (PAA) has received extensive attention in the water treatment due to its high oxidation potential and low toxicity of by-products. In this study, natural non-toxic mineral tourmaline (TM) was used to activate PAA to remove sulfadiazine (SDZ). The TM/PAA system could remove 92 ​% SDZ in 120 ​min. The radical analysis confirmed the co-existence of both free radical and non-free radical degradation pathways in the TM/PAA system, indicating that singlet oxygen (1O2) and acetyl(per)oxy radicals (CH3C(O)O· and CH3C(O)OO·) were the main reactive oxygen species. The Fe2+/Fe3+ ratio on the TM surface decreased during the degradation of SDZ due to Fe2+ consumption. The effect of water matrix on SDZ removal indicated that Cl−, SO42− and NO3− posed little effect on SDZ removal, while CO32− inhibited SDZ removal by affecting pH. Particularly, humic acid (HA) slightly promoted SDZ removal. Ten by-products of SDZ were identified by HPLC-MS/MS, and four possible transformation pathways (SO2 detachment, S–N breakage, amino acid oxidation, and hydroxylation) were proposed. TM was recycled five times and the removal of SDZ remained above 85 ​%, confirming its excellent reusability. This work indicates the TM/PAA system is of great potential for the application on the organic contaminant removal.