Removal Of Sulfamethazine Research Articles

Efficient catalytic degradation of sulfamethazine in aqueous solution by activation of peroxydisulfate with CuFeO2

In this work, the bimetallic oxide CuFeO2 was synthesized by simple hydrothermal synthesis and utilized to activate peroxydisulfate (PDS) for the sulfamethazine (SMT) degradation in water. The influence of some key factors such as CuFeO2 dose, PDS concentration and initial pH on the degradation of SMT was investigated. In particular, the CuFeO2/PDS system was capable of effectively degrading SMT under neutral and weak alkaline conditions. The mechanism of the CuFeO2/PDS system was revealed by quenching experiments and ESR tests. It involves a combined radical and non-radical mechanism with multiple active species (SO4•−, HO•, O2•− and 1O2) acting together. A synergistic interaction between iron and copper on the CuFeO2 surface accelerated the conversion of Fe(III) to Fe(II), which is one of the advantages of CuFeO2 over monometallic oxides. Furthermore, simulated experiments for the SMT degradation were conducted in different water matrices, and the effects of some inorganic ions (e.g. Cl-, SO42- and HCO3-) and humic acid were also explored. Exceptionally, HCO3- played a facilitating role for the removal of SMT. Finally, the CuFeO2/PDS system still exhibited superior performance after five cycles of testing. Overall, this study provided a cost-effective and promising strategy for the removal of antibiotics from the aqueous environment.

Low additive peracetic acid enhanced sulfamethazine degradation by permanganate: A mechanistic study

In this study, a novel water treatment process combining permanganate (Mn(VII)) and peracetic acid (PAA, CH3C(O)OOH) was employed to degrade sulfamethazine (SMT), a typical model contaminant. Simultaneous application of Mn(VII) and a small amount of PAA resulted in much faster oxidation of organics than a single oxidant. Interestingly, coexistent acetic acid played a crucial role in SMT degradation, while background hydrogen peroxide (H2O2) had a negligible effect. However, compared with acetic acid, PAA could better improve the oxidation performance of Mn(VII) and accelerate the removal of SMT more significantly. The mechanism of SMT degradation by Mn(VII)-PAA process was systematically evaluated. Firstly, based on the quenching experiments, electron spin resonance (EPR) results and UV–visible spectrum, singlet oxygen (1O2), Mn(III)aq and MnO2 colloids were the predominant active substances, while organic radicals (R-O•) showed negligible contribution. Then, the decay of Mn(VII) in the presence of PAA and H2O2 was investigated. It was found that the coexisting H2O2 accounted for almost all the decay of Mn(VII), PAA and acetic acid both had low reactivity toward Mn(VII). During the degradation process, acetic acid was able to acidify Mn(VII) and simultaneously acted as a ligand to form reactive complexes, while PAA mainly played a role of spontaneously decomposing to produce 1O2, they jointly promoted the mineralization of SMT. Finally, the degradation intermediates of SMT and their toxicities were analyzed. This paper reported the Mn(VII)-PAA water treatment process for the first time, which provided a promising approach for rapid decontamination of refractory organics-polluted water.

Immobilization of Bacillus Thuringiensis and applicability in removal of sulfamethazine from soil

Microbial degradation is considered an essential and promising treatment for sulfadimidine contamination of soil. To address the low colonization rates and inefficiencies of typical antibiotic-degrading bacteria, sulfamethazine (SM2)-degrading strain H38 is converted into immobilized bacteria in this study. Results show that the removal rate of SM2 by immobilized strain H38 reaches 98% at 36 h, whereas the removal rate of SM2 by free bacteria reaches 75.2% at 60 h. In addition, the immobilized bacteria H38 exhibits tolerance to a wide range of pH (5–9) and temperature (20 °C–40 °C). As the amount of inoculation increases and the initial concentration of SM2 decreases, the removal rate of SM2 by the immobilized strain H38 increases gradually. Laboratory soil remediation tests show that the immobilized strain H38 can remove 90.0% of SM2 from the soil on the 12th day, which exceeds the removal by free bacteria by 23.9% in the same period. Additionally, the results show that the immobilized strain H38 enhances the overall activity of microorganisms in SM2-contaminated soil. Compared with the SM2 only (control group containing no bacteria) and free bacterial treatment groups, the gene expression levels of ammonia-oxidizing archaea, ammonia-oxidizing bacteria, cbbLG, and cbbM increased significantly in the treatment group with immobilized strain H38. This study shows that immobilized strain H38 can reduce the effect of SM2 on soil ecology to a greater extent than free bacteria, while providing safe and effective remediation.

The complementary effect between biochar and ferrihydrite in sustainable Fenton-like oxidation of pollutant

Biochar (BC) and ferrihydrite (Fh) were used together in activation of H2O2 for removal of sulfamethazine (SMZ), a refractory antibiotic pollutant. The results show a complementary effect between biochar and ferrihydrite on activation of H2O2, namely biochar accelerated Fe(Ⅲ)/Fe(Ⅱ) cycle through electron donation/transfer, while ferrihydrite enhanced the yield of •OH through a sustainable release of dissolved Fe. Thus several times more •OH was produced in the co-activated system (BC + Fh/H2O2) than either in the ferrihydrite-catalyzed Fenton-like system (Fh/H2O2) or in the biochar-activated system (BC/H2O2). Consequently, a more efficient oxidation of SMZ was observed in BC + Fh/H2O2, in which the reaction rate constant (kobs) is 30.7 times in Fh/H2O2 and 6.08 times in BC/H2O2, respectively. This research provides a simple and sustainable strategy for enhancing the efficiency of Fenton-like oxidation of pollutants.

Functional fungal pellets self-immobilized by mycelium fragments of Irpex lacteus WRF-IL for efficient degradation of sulfamethazine as the sole carbon source

In order to achieve an efficient microbial material with dual functions of self-immobilization and sulfamethazine (SMZ) degradation, this study explored the pelletization technique utilizing mycelium fragments of Irpex lacteus WRF-IL and systematically examined the pellets formation conditions and degradation capability. The Box-Behnken design results demonstrated that pure mycelium fragments, broken by frosted glass beads, could be rapidly self-immobilized to form white rot mycelial pellets (WRMPs) within 24 h, serving as the pelleting core. These WRMPs could completely remove SMZ as the sole carbon source within 20 h. The addition of sucrose expedited this process, achieving complete removal within only 14 h. Kinetic analysis showed that WRMPs could potentially remove SMZ at higher concentrations (>25 mg/L). Biodegradation was the primary pathway of SMZ removal. Seven intermediates were identified by QTOF LC/MS, and three transformation pathways initiated by SO2 overflow, molecular rearrangement, and aniline moiety oxidation were deduced.

Biodegradation of trace sulfonamide antibiotics accelerated by substrates across oxic to anoxic conditions during column infiltration experiments

Frequent occurrence of trace organic contaminants in aquatic environments, such as sulfonamide antibiotics in rivers receiving reclaimed water, is concerning. Natural attenuation by soil and sediment is increasingly relied upon. In the case of riverbank filtration for water purification, the reliability of antibiotic attenuation has been called into question due to incomplete understanding of their degradation processes. This study investigated influence of substrates and redox evolution along infiltration path on biotransformation of sulfonamides. Eight sand columns (length: 28 cm) with a riverbed sediment layer at 3–8 cm were fed by groundwater-sourced tap water spiked with 1 μg/L of sulfadiazine (SDZ), sulfamethazine (SMZ), and sulfamethoxazole (SMX) each, with or without amendments of dissolved organic carbon (5 mg-C/L of 1:1 yeast and humics) or ammonium (5 mg-N/L). Two flow rates were tested over 120 days (0.5 mL/min and 0.1 mL/min). Iron-reducing conditions persisted in all columns for 27 days during the initial high flow period due to respiration of sediment organics, evolving to less reducing conditions until the subsequent low flow period to resume more reducing conditions. With surplus substrates, the spatial and temporal patterns of redox conditions differentiated among columns. The removal of SDZ and SMZ in effluents was usually low (15 ± 11%) even with carbon addition (14 ± 9%), increasing to 33 ± 23% with ammonium addition. By contrast, SMX removal was higher and more consistent among columns (46 ± 21%), with the maximum of 64 ± 9% under iron-reducing conditions. When sulfonamide removal was compared between columns for the same redox zones during infiltration, their enhancements were always associated with the availability of dissolved or particulate substrates, suggesting co-metabolism. Manipulation of the exposure time to optimal redox conditions with substrate amendments, rather than to simply prolong the overall residence time, is recommended for nature-based solutions to tackle target antibiotics.

Synergistic adsorption and degradation of sulfamethazine by tobacco stalk-derived activated biochar: Preparation, mechanism insight and application

Green preparation of high value-added products from biomass waste for environmental remediation has received significant attention. In this work, activated biochars were developed through two-step thermal process using tobacco stalk as the precursor. Textural properties of biochar can be effectively tuned by adjusting carbonization and activation parameters. An optimized biochar (700TS-1000–5), carbonized at 700 ℃ and then thermally activated at 1000 ℃ for 5 h, showed higher specific surface area (905.61 m2 g−1), rich porous structure, and abundant surface functional groups. 700TS-1000–5 showed excellent performance with a removal capacity of 99.37 mg g−1 for sulfamethazine (SMT) in 720 min, which was 4.3 times that of pristine biochar (700TS). And the SMT removal was high-efficient under normal environmental pH range. Adsorption and degradation simultaneously occurred during the whole process, which mainly relied on defects, functional groups, and·OH radicals. Moreover, this typical sample showed outstanding recycling ability and effectiveness of column experiment. Compared with KOH-assisted chemical activation, thermal activation had minor environmental impact and lower preparation cost through environmental and economic assessment. These findings not only propose a simple protocol for high-value reuse of agricultural waste but also shed new light on applications of tobacco stalk-derived biochar.

Novel self-sustained flow-through electrochemical advanced oxidation processes using nano-Fe0 confined B, N co-doped carbon nanotubes/graphite felt cathode: Higher mineralization efficiency under wider pH

To improve the mineralization efficiency of pollutants under wide pH ranges by self-sustained electrochemical advanced oxidation processes (EAOPs) without any reagent addition, a flow-through system based on the bifunctional cathode of B, N-doped carbon nanotubes embedded with nano-Fe0 particles that loaded on graphite felt (Fe@BN-C/GF) was developed. Dominant by 1O2 oxidation, the sulfamethazine (SMT) degradation rate and TOC removal in this recirculated flow-through system were 2.6 ∼ 3.3-folds and 1.4 ∼ 2.4-folds that of the batch system under the pH ranges of 3 ∼ 11, respectively. The SMT degradation performance was found not affected in the presence of HCO3–, NO3–, Cl-, K+, or humic acid (HA). The Fe@BN-C/GF cathode had more potential to treat enlarged wastewater by 5-folds during 10 h operation, and the SMT and TOC removal was 99% and 70.31%, respectively. The total phosphorus (TP), ammonia nitrogen (NH3-N) and TOC in reverse osmosis concentrate and secondary wastewater effluent could be simultaneously removed to <0.01 mg L-1 and 8 mg L-1 by this flow-through system with a low electric energy consumption (EEC) of 0.022 and 0.18 kWh gTOC-1, respectively. This EAOPs based on the flow-through Fe@BN-C/GF cathode was self-sustained, and had very promising application prospect of high mineralization of pollutants even for low-conductivity wastewater.

Exploring the potential of Fe(III)-EGTA and Fe(III)-DTPA as the catalysts to enhance UV/persulfate in the degradation of aqueous sulfamethazine.

The combination of UV and water-soluble Fe(III) complexes is an effective method for generating Fe(II) in situ for activating advanced oxidation processes. This study explored the potential of Fe(III)-diethylenetriaminepentaacetic acid (Fe(III)-DTPA) and Fe(III)-ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (Fe(III)-EGTA) in activating the UV/persulfate (UV/PS) for sulfamethazine removal. The initial screening showed that Fe(III)-EGTA and Fe(III)-DTPA could significantly improve the rate of sulfamethazine removal. The optimum molar ratios of persulfate to Fe(III)-DTPA and Fe(III)-EGTA were 100:1 and 100:2.5. The predicted percentage of sulfamethazine removal under the optimized conditions, obtained using response surface methodology, was ~99% for both catalysts. The pH range of 6 to 8 did not significantly affect the performance of UV/PS in the removal of sulfamethazine. The percentage sulfamethazine removal in the selected water samples was ranged from 93.6% to 99.6%, agreeing with the predicted value. The performance of both catalysts in activating UV/PS is comparable with that of the frequently used Fe(III)-EDDS. PRACTITIONERS POINTS: The potential of Fe(III)-DTPA and Fe(III)-EGTA in activating UV/persulfate (UV/PS) was explored. Fe(III)-DTPA and Fe(III)-EGTA improved the performance of UV/PS in sulfamethazine removal. Fe(III)-DTPA and Fe(III)-EGTA are effective in catalyzing UV/PS under pH 6 to 8. The performance of Fe(III)-DTPA and Fe(III)-EGTA is comparable with well-studied Fe(III)-EDDS.

Ti3+ self-doped and nitrogen-annealed TiO2 nanocone arrays photoanode for efficient visible-LED-light-driven photoelectrocatalytic degradation of sulfamethazine

Developing efficient, durable and visible-light-driven photoanode with excellent environmental adaptability is of great significance for photoelectrocatalytic (PEC) degradation of organic pollutants. In this work, a novel Ti3+ self-doped and nitrogen-annealed TiO2 nanocone arrays (Ti3+-TiO2NCs(N2)) photoanode was prepared for efficiently photoelectrocatalytic degradation of sulfamethazine (SMT) under visible light emitting diode (LED) irradiation, which obtained 98.68% removal for initial SMT concentration of 10 mg/L within 60 min. The visible light harvesting and charge transfer of TiO2NCs were significantly improved after nitrogen annealing treatment. Additionally, the introduction of moderate Ti3+ sites further lowered charge transport resistance and introduced a new impurity energy level, which efficiently accelerated the transmission of photogenerated carriers and then generated more h+ and active species to degrade pollutants. After 15 recycling degradation experiments, Ti3+-TiO2NCs(N2) still obtained more than 97% SMT removal, demonstrating highly durable. Also, it exhibited promising application prospect for treatment of real wastewaters (secondary effluent, pharmaceutical wastewater and mariculture wastewater).

Efficient removal of sulfamethazine by a magnetic recoverable CeO2/Fe3O4/natural zeolite catalyst in catalytic ozonation process

In order to realize the efficient removal of sulfamethazine (SMZ) and overcome the recycling difficulty of catalysts in a heterogeneous catalytic ozonation process, low-cost natural zeolite loaded with CeO2 and Fe3O4 (FC/HZ) was synthesized by the co-precipitation method. The FC/HZ catalyst could completely degrade SMZ and realize 39.6% removal of TOC through catalytic ozonation. Moreover, the FC/HZ catalyst exhibited high catalytic ozonation activity under a wide pH range and possessed excellent recyclability (&amp;gt;90%) and stability with a magnet. Based on experiment and material characterization, the possible catalytic mechanism and degradation pathway of SMZ was revealed. In brief, this study offered an effective strategy for preparing recyclable catalysts and eliminating SMZ in aqueous solution.

Kinetically simulation of photo-Fenton process in removal of sulfamethazine, ciprofloxacin, sulfathiazole and amoxicillin by Monte Carlo modeling

Kinetic Monte Carlo modeling was employed to investigate the kinetics and photodecomposition mechanism of sulfamethazine, ciprofloxacin, sulfathiazole, and amoxicillin antibiotics by the photo-Fenton process (iron(III) citrate/hydrogen peroxide in the presence of UV irradiation). The reaction kinetic mechanisms of each photo-Fenton degradation mentioned above have been achieved. The rate constants values for each step of the reaction mechanisms (including photo-Fenton process of antibiotics) were obtained as adjustable parameters by kinetic Monte Carlo simulation. The optimized values of iron(III) citrate and hydrogen peroxide were investigated through the obtaining the effect of their initial amounts on the rate of antibiotic elimination utilizing kinetic Monte Carlo simulation. The perfect agreement is observed between the simulation results and the experimental photo-Fenton data for the systems above.

Boron promoted Fe3+/peracetic acid process for sulfamethazine degradation: Efficiency, role of boron, and identification of the reactive species

In this work, boron (B) was used to promote Fe3+/peracetic acid (Fe3+/PAA) for the degradation of sulfamethazine (SMT). An SMT degradation efficiency of 9.1% was observed in the Fe3+/PAA system over 60 min, which was significantly increased to 99.3% in the B/Fe3+/PAA system over 10 min. The B/Fe3+/PAA process also exhibited superior resistance to natural substances, excellent adaptability to different harmful substances, and good removal of antibiotics in natural fresh water samples. The mechanism of action of boron for Fe3+ reduction was determined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, density functional theory (DFT) calculations, and electrochemical tests. The dominant role of •OH was confirmed using quenching experiments, electron spin resonance (EPR) spectroscopy, and quantitative tests. Organic radicals (R-O•) and Fe(IV) also significantly contribute to the removal of SMT. DFT calculations on the reaction between Fe2+ and the PAA were conducted to further determine the contribution from •OH, R-O•, and Fe(IV) from the perspective of thermodynamics and the reaction pathways. Different boron dosages, Fe3+ dosages, and initial pH values were also investigated in the B/Fe3+/PAA system to study their effect of SMT removal and the production of the reactive species. Fe(IV) production determined the kR-O•+Fe(IV) value suggesting that Fe(IV) may play a more important role than R-O•. A comparison of the results with other processes has also proved that the procedure described in this study (B/Fe3+/PAA) is an effective method for the degradation of antibiotics.

Bifunctional Mo-doped FeCo–Se aerogels catalysts with excellent OER and ORR activities for electro-Fenton process

Antibiotic pollution in aqueous solutions seriously endangers the natural environment and public health. In this work, Mo-doped transition metal FeCo–Se metal aerogels (MAs) were investigated as bifunctional catalysts for the removal of sulfamethazine (SMT) in solution. The optimal Mo0.3Fe1Co3–Se catalyst can remove 97.7% of SMT within 60 min (SMT content: 10 mg/L, current intensity: 10 mA/cm2). The unique porous cross-linked structure of aerogel confered the catalyst sufficient active sites and efficient mass transfer channels. For the anode, Mo0.3Fe1Co3–Se MAs exhibits superior oxygen evolution reaction (OER) property, with an overpotential of only 235 mV (10 mA/cm2). Compared with Fe1Co3 MAs or Mo0.3Fe1Co3 MAs, density functional theory (DFT) demonstrated that the better catalytic capacity of Mo0.3Fe1Co3–Se MAs is attributed to the doping of Mo species and selenization lowers the energy barrier for the ∗OOH to O2 step in the OER process. Excellent OER performance ensures the self-oxygenation in this system, avoiding the addition of air or oxygen in the traditional electro-Fenton process. For the cathode, Mo doping can lead to the lattice contraction and metallic character of CoSe2, which is beneficial to accelerate electron transfer. The adjacent Co active sites effectively adsorb ∗OOH and inhibit the breakage of the O–O bond. Rotating ring disk electrode (RRDE) test indicated that Mo0.3Fe1Co3–Se MAs has an excellent 2e− ORR activity with H2O2 selectivity up to 88%, and the generated H2O2 is activated by the adjacent Fe site through heterogeneous Fenton process to generate ·OH.

Enhanced Heterogeneous Fenton-like Process for Sulfamethazine Removal via Dual-Reaction-Center Fe-Mo/rGO Catalyst

A heterogeneous Fenton-like catalyst with single redox site has a rate-limiting step in oxidant activation, which limited its application in wastewater purification. To overcome this, a bimetallic doping strategy was designed to prepare a heterogeneous Fenton-like catalyst (Fe-Mo/rGO) with a double-reaction center. Combined with electrochemical impedance spectroscopy and density functional theory calculation, it was confirmed that the formation of an electron-rich Mo center and an electron-deficient Fe center through the constructed Fe-O-Mo and Mo-S-C bonding bridges induced a higher electron transfer capability in the Fe-Mo/rGO catalyst. The designed Fe-Mo/rGO catalyst exhibited excellent sulfamethazine (SMT) degradation efficiency in a broad pH range (4.8-8.4). The catalytic performance was hardly affected by inorganic anions (Cl-, SO42- and HCO3-) in the complicated and variable water environment. Compared to Fe/rGO and Mo/rGO catalysts, the SMT degradation efficiency increased by about 14.6 and 1.6 times in heterogeneous Fenton-like reaction over Fe-Mo/rGO catalyst. The electron spin resonance and radical scavenger experiments proved that ·O2-/HO2· and 1O2 dominate the SMT removal in the Fe-Mo/rGO/H2O2 system. Fe and Mo, as active centers co-supported on rGO, significantly enhanced the electron transfer between catalyst, oxidant, and pollutants, which accelerated the reactive oxygen species generation and effectively improved the SMT degradation. Our findings offer a novel perspective to enhance the performance of heterogeneous Fenton-like catalysts by accelerating the electron transfer rate in the degradation of organic pollutants.

Rapid adsorption of sulfamethazine on mesoporous graphene produced from plastic waste: optimization, mechanism, isotherms, kinetics, and thermodynamics

Sulfonamide antibiotics like sulfamethazine (SMZ) can threaten aquatic and terrestrial life even in small concentrations (≤ 1 mg/L); hence, their removal from wastewater is indispensable. However, the need to explore new promising adsorbents that are cheap, effective, and reusable also remains crucial to developing adsorption technology. This work presents a one-pot solvent-free conversion of the current most ubiquitous anthropogenic bio-resistant solid waste (plastics) into valuable carbon materials to remove SMZ from aqueous solution. High-density polyethylene waste was pyrolyzed at 500–1000 °C in an enclosed stainless-steel reactor to produce mesoporous graphene. The graphene products were characterized via microscopic and spectroscopic analyses. The effect of temperature on the graphene yield and properties was investigated. The optimum sulfamethazine (SMZ) adsorption was achieved with 600 °C carbon product (CP-600) due to its high porosity and aromatic structure. The adsorption parameters (pH, catalyst dose, and SMZ concentration) were optimized by response surface methodology (RSM) with a central composite design. 99.99% SMZ removal was achieved at 0.9 g/L adsorbent dose, 12.4 mg/L SMZ concentration, and pH 3 at 25 °C. FTIR analysis revealed that the SMZ adsorption occurred mainly via π–π/π+–π electron interactions between the aromatic and pyrimidine rings of SMZ and the benzene ring of graphitic CP-600. The SMZ adsorption followed the pseudo-second-order kinetics, Langmuir, and Freundlich isotherm models. The adsorption was controlled by film and intraparticle diffusion and was spontaneous and endothermic. The carbon synthesized in this work is reusable and can rapidly remove more SMZ than other SMZ adsorbents.

Visible-light-driven g-C3N4 doped CuFe2O4 floating catalyst enhanced peroxymonosulfate activation for sulfamethazine removal via singlet oxygen and high-valent metal-oxo species

In this study, floating carbon nitride incorporating copper ferrite catalyst (CNCFEp) was synthesized by a simple coprecipitation-calcination method. The prepared catalyst was applied to the catalytic activation of peroxymonosulfate (PMS) for the degradation of antibiotics under visible light irradiation (Vis/CNCFEp/PMS system). In the presence of CNCFEp (2.0 g/L) and PMS (0.1 g/L), 97.6 % of sulfamethazine (SMT, 10 mg/L) was degraded in 30 min under neutral conditions, whereas negligible influence was observed accompanied by water matrixes. The floating composite catalyst showed excellent stability after 5 times recycling experiments. Singlet oxygen (1O2) and high-valent oxo-metal species were unveiled to be the major reactive oxygen species (ROS), rather than conventional hydroxyl radicals or sulfate radicals. These nonradical species were produced by direct oxidation or the transformation of superoxide ions and metastable metal composite at neutral pH. SMT was broken down by four degradation pathways in this system and a remarkable reduction in toxicity has been demonstrated by the quantitative structure–activity relationship (QSAR) prediction. Likewise, the nonradical species were capable of inactivating the bacteria (E. coli). This work was the first study dedicated to the mechanism of PMS activation by CNCFEp and provides a novel catalytic system for removal of organic contaminants and bacteria in environmental waters.

Enhanced removal of sulfonamide antibiotics from water by phosphogypsum modified biochar composite

Antibiotic pollution has become a global eco-environmental issue. To reduce sulfonamide antibiotics in water and improve resource utilization of solid wastes, phosphogypsum modified biochar composite (PMBC) was prepared via facile one-step from distillers grains, wood chips, and phosphogypsum. The physicochemical properties of PMBC were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), Zeta potential, X-ray diffraction (XRD), etc. The influencing factors, adsorption behaviors, and mechanisms of sulfadiazine (SD) and sulfamethazine (SMT) onto PMBC were studied by batch and fixed bed column adsorption experiments. The results showed that the removal rates of SD and SMT increased with the increase of phosphogypsum proportion, while decreased with the increase of solution pH. The maximum adsorption capacities of modified distillers grain and wood chips biochars for SD were 2.98 and 4.18 mg/g, and for SMT were 4.40 and 8.91 mg/g, respectively, which was 9.0–22.3 times that of pristine biochar. Fixed bed column results demonstrated that PMBC had good adsorption capacities for SD and SMT. When the solution flow rate was 2.0 mL/min and the dosage of PMBC was 5.0 g, the removal rates of SD and SMT by modified wood chips biochar were both higher than 50% in 4 hr. The main mechanisms of SD and SMT removal by PMBC are hydrogen bonding, π-π donor-acceptor, electrostatic interaction, and hydrophobic interaction. This study provides an effective method for the removal of antibiotics in water and the resource utilization of phosphogypsum.

Enhanced degradation of sulfamethazine in boron-doped diamond anode system via utilization of by-product oxygen and pyrite: Mechanism and pharmaceutical activity removal assessment

Treatment of antibiotic contaminants from water has become an urgent problem due to that antibiotic pollution may threaten the ecosystem. This study explored the feasibility of enhancement of boron-doped diamond (BDD) anode system for antibiotic removal by utilization of by-product oxygen and natural pyrite catalyst. Sulfamethazine (SMZ), one of commonly detected antibiotics in the aquatic environment, was selected. Completed degradation of SMZ was achieved within 60 min, when 3 g/L pyrite was added into BDD-nickel foam (NiF) electrochemical system. The pseudo first-order reaction rate constant for SMZ degradation in BDD-NiF-pyrite electrochemical system was approximately 9 times higher than that in BDD-NiF electrochemical system. The optimal conditions of BDD-NiF-pyrite electrochemical system for SMZ degradation were: current intensity of 50 mA, pyrite dosage of 3 g/L, initial pH = 3, and reaction time of 60 min at room temperature (25 ± 1 ℃). The OH and O2− radicals were responsible for SMZ degradation. SMZ degradation intermediates were identified. Possible SMZ degradation pathways were also proposed. Furthermore, in vivo pharmaceutical activity removal of SMZ was assessed by zebrafish inflammation model. SMZ before treatment exhibited anti-inflammatory activity while lost it after treatment. This study offered an alternative approach to boost the BDD electrochemical oxidation of antibiotic-contaminated water.

Magnetic mesoporous TiO2/Fe3O4 nanocomposite adsorbent for removal of sulfamethazine from water

• A new way to make mesoporous, magnetic, and reusable nanocomposite adsorbents. • Accelerated adsorption kinetics for fast removal of sulfamethazine from water. • Able to achieve very high sulfamethazine adsorption capacity in a specific pH ranges. We report a magnetic nanocomposite of mesoporous TiO 2 coatings on Fe 3 O 4 nanoparticles (m-TiO 2 /Fe 3 O 4 ) that shows highly efficient adsorption of sulfamethazine (SMZ), an antibiotic molecule, from water. The nanocomposite was prepared using a unique surface coating process that produces a mesoporous TiO 2 structure with a high specific surface area. It was found that the m-TiO 2 /Fe 3 O 4 can adsorb SMZ from aqueous solutions, with the highest adsorption capacity of 270.3 ± 0.65 mg g −1 . The SMZ removal efficiency is around 88% at pH between 3.17 and 7.01 within a short equilibrium time of 40 min. It was found that the experimental data can be best fit with a pseudo-second-order kinetics model for the SMZ adsorption and the SMZ adsorption is through hydrogen bonding as well as hydrophobic interactions.