Adsorption Of Sulfamethoxazole Research Articles

Development of a novel polydopamine-imprinted MOFs targeted for removal of refractory organic pollutants: Synergistic mechanisms of adsorption and degradation

In this study, a novel dopamine-imprinted MOFs (metal organic frameworks) was developed for the first time to achieve targeted degradation of refractory organic pollutants (ROPs) in advanced oxidation process. The targeted adsorption and degradation capacity of sulfamethoxazole (SMX) by molecularly imprinted catalyst (Fe-MOFs@MIP) was 3.17 times and 5.47 times that of Fe-MOFs, respectively. The results showed that the polydopamine (PDA) imprinted layer not only enhanced the targeted adsorption of SMX, but also improved the activity of the catalyst by promoting electron transfer. The physicochemical properties of Fe-MOFs@MIP were investigated. In situ Fourier transform infrared spectroscopy and molecular dynamics theory were used to investigate targeted adsorption mechanism. The active species were identified by quenching experiments and electron paramagnetic resonance (EPR). The reaction sites of SMX were predicted using density functional theory (DFT) and the possible degradation pathways of SMX were proposed. Finally, the targeted degradation mechanism of Fe-MOFs@MIP was elucidated. This study has a guiding significance for the deep removal of refractory organic pollutants in wastewater.

Unary adsorption of sulfonamide antibiotics onto pozzolan-tyre ash based geopolymers: Isotherms, kinetics and mechanisms

In this contribution, geopolymer composites, GP0, GP5-TA and GP10-TA, were prepared by alkaline activation and substituting pozzolan (Pz) with 0, 5 and 10wt % of tyre ash (TA), respectively. The geopolymers were characterized using standard methods (XRD, TGA, FTIR, BET, SEM, Boehm titration and methylene blue and iodine indices) and were applied for the abatement of two sulfonamides, sulfamethoxazole (SMX) and sulfadimethoxine (SDM) in single-solute solutions. The effects of pH, salinity, initial concentration and contact time were evaluated. The incorporation of 5 and 10% TA increased the specific surface area (SSA) of pristine geopolymer (GP0) from 13.62 to 21.48 and 29.70 m2.g-1, respectively. The equilibrium data was best described by the Sips isotherm model. Salinity significantly diminished the adsorption of SMX and SDM. In aqueous medium, the geopolymers exhibited higher adsorption capacity for SDM (log Kow, 1.17) relative to SMX (log Kow, 0.86). In contrast, in saline medium, SMX uptake was higher, suggesting a cation-mediated adsorption. Adsorption of SMX was uncharacteristically independent of pH, whereas SDM uptake was significantly pH-dependent. The GP5-TA geopolymer composite exhibited the highest adsorption capacity for SMX in a saline environment (46.69mg.g-1) and for SDM in non-saline water (107.69mg.g-1). Adsorption rate was described by the pseudo-second order kinetic law. Adsorption mechanism was multi-mechanistic involving hydrophobic, ion exchange and charge assisted hydrogen bonding and electrostatic interactions in the case of SDM. Future works should optimize the functional groups density of active sites especially for sulfonamides in saline waters.

Adsorption of sulfamethoxazole and ethofumesate in biochar- and organoclay-amended soil: Changes with adsorbent aging in the laboratory and in the field

Biochars and organoclays have been proposed as efficient adsorbents to reduce the mobility of agrochemicals in soils. However, following their application to soils, these adsorbents undergo changes in their physicochemical properties over time due to their interaction with soil components. In this study, the adsorption capacity of a commercial biochar and a commercial organoclay for the antibiotic sulfamethoxazole (SFMX) and the pesticide ethofumesate (ETFM) was evaluated over aging periods of 3 months in the laboratory and 1 year in the field, subsequent to their application to a Mediterranean soil. The results showed that the adsorption of SFMX and ETFM in the soil amended with the adsorbents was greater than in the unamended soil, but for both chemicals, adsorption decreased with aging of the adsorbents in the soil. Characterization of the adsorbents before and after aging revealed physical blocking of adsorption sites by soil components. The loss of adsorption capacity of the adsorbents upon aging led to higher leaching of SFMX and ETFM in the soil containing field-aged adsorbents, although leaching remained lower than in unamended soil. Our findings reveal that, under the Mediterranean environment studied, the efficacy of the studied materials as adsorbents is maintained to a considerable extent for at least one year after their field application, which would have positive implications in their use for attenuating the dispersion of agricultural contaminants in the environment.

Sulfur Vacancies in Pyrite Trigger the Path to Nonradical Singlet Oxygen and Spontaneous Sulfamethoxazole Degradation: Unveiling the Hidden Potential in Sediments.

Pharmaceutical residues in sediments are concerning as ubiquitous emerging contaminants. Pyrite is the most abundant sulfide minerals in the estuarine and coastal sediments, making it a major sink for pharmaceutical pollutants such as sulfamethoxazole (SMX). However, research on the adsorption and redox behaviors of SMX on the pyrite surface is limited. Here, we investigated the impact of the nonphotochemical process of pyrite on the fate of coexisting SMX. Remarkably, sulfur vacancies (SVs) on pyrite promoted the generation of nonradical species (hydrogen peroxide, H2O2 and singlet oxygen, 1O2), thereby exhibiting prominent SMX degradation performance under darkness. Nonradical 1O2 contributed approximately 73.1% of the total SMX degradation. The SVs with high surrounding electron density showed an advanced affinity for adsorbing O2 and then initiated redox reactions in the sediment electron-storing geobattery pyrite, resulting in the extensive generation of H2O2 through a two-electron oxygen reduction pathway. Surface Fe(III) (hydro)oxides on pyrite facilitated the decomposition of H2O2 to 1O2 generation. Distinct nonradical products were observed in all investigated estuarine and coastal samples with the concentrations of H2O2 ranging from 1.96 to 2.94 μM, while the concentrations of 1O2 ranged from 4.63 × 10-15 to 8.93 × 10-15 M. This dark-redox pathway outperformed traditional photochemical routes for pollutant degradation, broadening the possibilities for nonradical species use in estuarine and coastal sediments. Our study highlighted the SV-triggered process as a ubiquitous yet previously overlooked source of nonradical species, which offered fresh insights into geochemical processes and the dynamics of pollutants in regions of frequent redox oscillations and sulfur-rich sediments.

Adsorption effects of electron scavengers and inorganic ions on catalysts for catalytic oxidation of sulfamethoxazole in radiation treatment

This study aimed to investigate adsorption effects of electron scavengers (H2O2 and S2O82−) on oxidation performance for mineralization of sulfamethoxazole (SMX) in radiation treatment using catalysts (Al2O3, TiO2). Hydrogen peroxide (H2O2, 1 mM) as an electron scavenger showed weak adsorption onto catalysts (0.012 mmol g−1-Al2O3 and 0.004 mmol g−1-TiO2, respectively), leading to an increase in TOC removal efficiency of SMX within the absorbed dose of 30 kGy by 12.3% with Al2O3 and by 8.0% with TiO2. The weak adsorption of H2O2 onto the catalyst allowed it to act as an electron scavenger, promoting indirect decomposition reactions. However, high adsorption of S2O82− (1 mM) onto Al2O3 (0.266 mmol g−1-Al2O3) showed a decrease in TOC removal efficiency of SMX from 76.2% to 30.2% within the absorbed dose of 30 kGy. The high adsorption of S2O82− onto the catalyst inhibited direct decomposition reaction by reducing adsorption of SMX on catalysts. TOC removal efficiency for Al2O3 without electron scavengers in an acidic condition was higher than that in a neutral or alkaline condition. However, TOC removal efficiency for Al2O3 with S2O82− was higher in a neutral condition than in other pH conditions. This indicates that the pH of a solution plays a critical role in the catalytic oxidation performance by determining surface charges of catalysts and yield of reactive radicals produced from water radiolysis. In the radiocatalytic system, H2O2 enhances the oxidation performance of catalysts (Al2O3 and TiO2) over a wide pH range (3–11). Meanwhile, S2O82− is not suitable with Al2O3 in acidic conditions because of its strong adsorption onto Al2O3 in this study.

Magnetic Chitosan for the Removal of Sulfamethoxazole from Tertiary Wastewaters.

Magnetic chitosan nanoparticles, synthesized by in situ precipitation, have been used as adsorbents to remove sulfamethoxazole (SMX), a sulfonamide antibiotic dangerous due to its capacity to enter ecosystems. The adsorption of SMX has been carried out in the presence of tertiary wastewaters from a depuration plant to obtain more realistic results. The effect of pH on the adsorption capacity significantly changed when carrying out the experiments in the presence of wastewater. This change has been explained while taking into account the charge properties of both the antibiotic and the magnetic chitosan. The composition of wastewaters has been characterized and discussed as regards its effect on the adsorption capacity of the magnetic chitosan. The models of Elovich and Freundlich have been selected to describe the adsorption kinetics and the adsorption isotherms, respectively. The analysis of these models has suggested that the adsorption mechanism is based on strong chemical interactions between the SMX and the magnetic chitosan, leading to the formation of an SMX multilayer.

Insight into the Role of the Pore Structure and Surface Functional Groups in Biochar on the Adsorption of Sulfamethoxazole from Synthetic Urine

The study assessed the influence of pyrolysis temperature on the properties of hickory sawdust and peanut shells based biochar, particularly its pore structure, surface functional groups, and adsorption capacity. Results from SEM analysis demonstrated that higher pyrolysis temperatures led to an enhanced pore structure and surface roughness in biochars, providing increased adsorption capacity. Raman spectrum analysis revealed higher levels of disorder and graphitization in biochars pyrolyzed at elevated temperatures. Quantification of surface functional groups using the Boehm method indicated a shift in the abundance of basic and acidic groups under high pyrolysis conditions. Employing the FHH model, fractal characteristics were observed in the pore structure of different biochars, with high-temperature biochars displaying increased disorder. The study also explored the mechanism of SMX adsorption onto biochars, revealing higher adsorption capacity for biochars with richer pore structures and rougher surfaces. The Elovich model proved to be the best fit for describing the chemisorption process of SMX onto the biochars. Moreover, the study demonstrated the impact of urine ions on SMX adsorption onto the biochars. These findings provide valuable insights into the properties and potential applications of biochars in environmental remediation.

ZIF-8 templated mesoporous triazine covalent-organic polymer for adsorptive removal of sulfonamides from water

A highly porous covalent-organic polymer with mesoporosity (named MT-MCTP) was prepared for the first time via ZIF-8 (a zeolitic imidazolate framework, comprised of ZnN4 tetrahedral units interconnected by methyl imidazolate linkers) templated synthesis of microporous triazine polymer (MCTP) and subsequent removal of ZIF-8. MT-MCTP had higher porosity and wider pore size than the conventional MCTP. The prepared MT-MCTP, together with MCTP and commercial activated carbon (AC), was applied to the adsorptive elimination of sulfonamides like sulfamethoxazole and sulfachlorpyridazine from water. MT-MCTP showed the highest kinetic constants among the three adsorbents in the sulfonamides adsorption because of the developed mesopores obtained with the sacrificial ZIF-8 template. Additionally, the adsorbed amounts of sulfamethoxazole and sulfachlorpyridazine over the adsorbents decreased in the order: MT-MCTP > MCTP > AC. MT-MCTP had a maximum adsorption capacity (Q0) of 557 and 534 mg/g for sulfamethoxazole and sulfachlorpyridazine, respectively, which are much higher than the capacity observed with AC. Importantly, MT-MCTP is a recyclable adsorbent with the highest Q0 for sulfamethoxazole compared with any reported results, so far, in near-neutral conditions. Based on the adsorption and surface charge under wide pH ranges, the noticeable sulfamethoxazole adsorption over MT-MCTP could be interpreted with the favorable pore structure (mesopore), surface charge, π–π interaction, and hydrogen bonding interaction.

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.

Innovative approaches to suppress non-specific adsorption in molecularly imprinted polymers for sensing applications

Molecularly imprinted polymers (MIPs) are synthetic antibodies developed to bind selectively with specific molecules. They function through a particular recognition process involving their cavities and functional groups. Nevertheless, functional groups located outside these cavities are the main cause of non-specific molecule binding, thus reducing the effectiveness of MIPs in sensing applications. This work focused on enhancing the selectivity and performance of MIPs through electrostatic modification with surfactants. The study investigates the use of two surfactants, namely sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB), to eliminate non-specific adsorption in MIPs. The binding isotherms of the target molecule sulfamethoxazole (SMX) on MIPs and non-imprinted polymers (NIPs) were analyzed, showing higher adsorption capacity of MIPs due to the specific cavities. The modification with SDS or CTAB effectively eliminated non-specific adsorption in MIPs. The kinetic adsorption behavior further demonstrated the efficacy of MIP+--SDS/CTAB in the selective adsorption of SMX. Calibration curves showcase the methodology's analytical capabilities, achieving low limit of detection for SMX 6 ng mL−1 using MIP +-SDS. The stability study confirmed that the developed MIP +/--SDS/CTAB remains stable even at high temperatures, demonstrating its suitability for on-site applications. The methodology was successfully applied to detect SMX in milk and water samples, achieving promising recoveries. Overall, the electrostatic modification of MIPs with surfactants emerges as a valuable strategy for enhancing selectivity and performance in target molecule recognition and detection.

Adsorption of sulfamethoxazole on a biochar developed from reed canary grass: characteristics of adsorption equilibrium and energetical analysis

Adsorption of sulfamethoxazole on a biochar developed from reed canary grass: characteristics of adsorption equilibrium and energetical analysis

Single and multicomponent adsorption of amoxicillin, ciprofloxacin, and sulfamethoxazole on chitosan-carbon nanotubes hydrogel beads from aqueous solutions: Kinetics, isotherms, and thermodynamic parameters

The removal of antibiotics in water receiving bodies is an integral part in eradicating antimicrobial resistance which has become a major threat to public health. Solid-liquid adsorption has demonstrated to be an effective technique in the removal of antibiotics from aqueous environments. Herein, chitosan-carbon nanotube (chitosan-CNT) hydrogel beads were synthesised for the adsorption of amoxicillin (AMX), ciprofloxacin (CIP) and sulfamethoxazole (SMX) from aqueous solution. Adsorption kinetics, isotherms and thermodynamic parameters were systematically investigated at a solution pH of 7. Single adsorption kinetics findings suggest that experimental data for AMX, CIP and SMX was better fitted by the nonlinear pseudo-first order model with calculated maximum adsorption capacities of 23.1 mg.g−1, 23.7 mg.g−1 and 25.17 mg.g−1, respectively. Moreover, findings from the Weber-Morris kinetic model suggest that multiple processes were limiting the overall adsorption rate of AMX, CIP and SMX on chitosan-CNT. Adsorption isotherm results indicated that single adsorption experimental data was better fitted by the nonlinear Freundlich isotherm model, while binary and ternary system experimental data were better fitted by the nonlinear competitive extended Sips adsorption isotherm models. Moreover, results for binary and ternary adsorption showed that multicomponent adsorption systems exhibited both antagonistic and synergistic adsorption of AMX, CIP and SMX. From the thermodynamics fundings, it was evident that the adsorption of AMX, CIP and SMX from solution is an endothermic process governed by both physical and chemical adsorption mechanisms. Based on the findings of the current study, it was concluded that chitosan-CNT has potential as a green technology for the removal of antibiotics from solution.

Chlorella sp. EPS loaded alginate microsphere: A novel bionanomaterial for adsorptive removal of sulfamethoxazole from the aqueous solutions

Microalgae exopolysaccharide (EPS) emerge as a sustainable and ecologically robust approach for wastewater treatment, leveraging their inherent capabilities for the adsorption and efficient removal of pollutants. This study proposes novel microalgae EPS polymerized with alginate to form an adsorbent microsphere that can efficiently remove sulfamethoxazole (SMX) from water. The EPS extracted from Chlorella sp. contains different functional groups like amides and polysaccharides that play a significant role in SMX adsorption. FT-IR and 3D-EEM analysis showed that electrostatic attraction is the primary binding force in the adsorption process. The decrease in both the TOC (total organic carbon) value of the SMX solution and its toxicity confirmed the effective adsorption of SMX. When the pH was 7.0, the composite weight was 30 g, and the SMX concentration was 10 mg/L, over 90% of SMX was removed in 90 min. The batch study showed that the pseudo-first-order kinetics and Langmuir adsorption isotherm model fit best. Column studies also showed the potential for semi-industrial scale-up, achieving 98% removal in 800 min, and fitting well to the Adams-Bohart column kinetic model. These conditional changes increase surface area, porosity, and specific binding affinities, optimizing antibiotic remediation by improving adsorption kinetics and responsiveness to environmental conditions. The EPS-alginate-mediated adsorption process is safe-by-design and economical, making the proposed composite adsorbent material highly efficient.

Insight into the adsorption and co-adsorption of PPCPs on Ti3C2Tx MXene: Behaviors, mechanisms and application potentials

In this study, four pharmaceutical compounds including sulfamethoxazole (SMX), oxytetracycline (OTC), ciprofloxacin (CIP), and ibuprofen (IBU) with different functional groups and pKa, were selected as representative pollutants to systematically investigate the Pharmaceutical and Personal Care Products (PPCPs) adsorption on a nanomaterial Ti3C2Tx MXene in simulated solution and real surface water. The results show that Ti3C2Tx was an excellent PPCPs adsorbent, but the process was affected by the characteristics of pollutants pronouncedly, the obtained maximum adsorption capacity were OTC (210.97 mg/g) > IBU (185.05 mg/g) > CIP (160.60 mg/g) > SMX (68.12 mg/g). Specially, the charge screen effect caused Ti3C2Tx precipitation during CIP adsorption. The response surface methodology analysis indicates that initial solution pH (3–11) had significant effects, while the influence of humic acid (0–10 mg/L) or sodium chloride (0–10 mg/L) was limited, and the interactions between these factors was slight. In the co-adsorption process, the competitive effects reduced the adsorption of SMX and IBU, however, the enhanced positive ionization and the possible electrostatic repulsive interactions promoted that of CIP and OTC. In real surface water, although the influence of natural organic matters was negligible, the preferential adsorption of background metal ions such as aluminum and calcium ions reduced the adsorption capacity of the selected PPCPs by approximately 29.9 % to 88.4 %. Moreover, the adsorbent characterization conjoined with performance examination imply that electrostatic attraction dominated the Ti3C2Tx adsorption of PPCPs, and hydrogen bonding interactions as well as surface complexation might also contributed. These observations suggest that Ti3C2Tx MXene has the potential for use as adsorbent to eliminate aqueous PPCPs, nevertheless, the interference of co-existing metal ions and the stability of adsorbent were also noteworthy.

Efficient removal of antibiotic from aqueous solutions using adsorbent derived from zeolitic imidazolate framework-8

The effective removal of common refractory antibiotics from livestock and poultry farming wastewater has attracted widespread attention. Developing high-performance adsorbents for the removal of antibiotics from wastewater is a highly promising method. Herein, a derivative from zeolitic imidazolate framework-8 (D-ZIF-8) was successfully prepared, characterized, and used for the adsorption of sulfamethoxazole (SMZ). Results showed that the D-ZIF-8 was a superior mesoporous adsorbent for antibiotic removal from wastewater, with a large specific surface area, pore size, and pore volume. Under suitable adsorption conditions, such as pH of 5.5, temperature of 25 ℃, initial concentration of SMZ of 10 mg/L, and D-ZIF-8 dosage of 0.1 g/L, the adsorption of SMZ on D-ZIF-8 could reach equilibrium at 5 h, and the removal efficiency and adsorption capacity of SMZ reached to 95.0% and 95.0 mg/g, respectively. Moreover, the D-ZIF-8 adsorbent also had good reusability. After 4 cycles, the adsorption capacity of SMZ on D-ZIF-8 remained at 93% of the initial adsorption capacity. In addition, the results of kinetic, adsorption isotherm, and thermodynamic analysis indicated that the adsorption of SMZ on D-ZIF-8 belonged to multi-layer chemical adsorption and was a spontaneous exothermic reaction. This investigation could provide an efficient method for the removal of refractory antibiotics from livestock and poultry farm wastewater.

Evaluation of different functionalization methodologies for improving the removal of three target antibiotics from wastewater by a brewery waste activated carbon

This work aims to increase the efficiency of an activated carbon produced from brewery waste (AC) in the removal of three target antibiotics (sulfamethoxazole (SMX), trimethoprim (TMP), and ciprofloxacin (CIP)) by surface incorporation of oxygen, nitrogen or sulfur groups. AC was produced using spent brewery grains (the most abundant waste from the brewing industry) as raw material, K2CO3 as activating agent and microwave energy for pyrolysis. Then, seven different functionalized AC were prepared, characterized for their physicochemical properties, and tested for adsorption (%) of SMX, TMP and CIP from three different matrices (ultrapure water (pH ~5–6), buffered ultrapure water (pH 8), and effluent from a municipal wastewater treatment plant (WWTP effluent (pH 8)), under batch operation. Based on the obtained results, an oxygen functionalized AC was selected for further characterization and studies on the adsorption of the target antibiotics from the WWTP effluent. Kinetic results fitted the pseudo-second order model and the equilibrium isotherms were adequately described by the Langmuir model, reaching maximum adsorption capacities (qm) of 124 ± 1 μmol g−1, 315 ± 2 μmol g−1 and 201 ± 5 μmol g−1 for SMX, TMP and CIP, respectively. The selected functionalization increased qm by up to 58 % in comparison with the non-functionalized AC. The oxygen modified AC produced from a biomass waste remarkably improved its performance for an efficient application in the removal of antibiotics from wastewater.

Facile synthesis of ball milling and magnetization co-modified sludge-derived biochar for efficient adsorbing environmental concentration sulfamethoxazole from various waters: Performance and mechanism

The overuse of sulfamethoxazole (SMX) has caused serious damage to aquatic ecosystem and human health even at environmental concentration. In this study, various iron salts were used to functionalize sludge-derived biochar (SBC) to simultaneously boost its adsorption ability for SMX and magnetic collection performance. Afterward, ball milling was further employed to treat optimal iron salt (FeCl3▪6H2O) functionalized SBC (MSBC) for enlarging its external-internal surface area, pore volume and exposing its functional groups. Ball milling coupled FeCl3▪6H2O co-modified SBC (BMSBC) showed the desirable adsorption performance for SMX, and it was remarkably higher than those of SBC, ball milled SBC (BSBC), MSBC and other magnetization functionalized SBC. The maximum adsorption capacity of BMSBC calculated by Langmuir model was 2.24 × 104 μg/g, and it showed the optimum adsorption performance at pH = 3 and 5. The multiple physicochemical forces including π-π conjugation, pore filling, H-bonding (dipole–dipole and Yoshida), Fe-O complexation and electrostatic interactions were confirmed as the dominant driving mechanism controlling SMX adsorption onto BMSBC by adsorption models fitting, water chemistry effect experiments, characterization analysis and DFT calculation. The greater magnetic sensitivity guaranteed it was easily collected within 1 min, also was beneficial for its reuse by NaOH regeneration. The favorable adsorption ability for SMX in actual waters and good environmental safety of BMSBC allowed it to be a viable adsorbent, in addition to the disposal approach for sludge.

Physicochemical and adsorptive properties of biochar derived from municipal sludge: sulfamethoxazole adsorption and underlying mechanism

Municipal sludge waste could be transformed into useful biochar through pyrolysis process. In this study, municipal sludge-derived biochar (SBC) was successfully synthesized via the one-pot pyrolysis method, and the yield of sludge biochar gradually decreased with the pyrolysis temperature increased from 300°C to 800°C. The sludge biochar exhibited an alkaline surface due to the gradual accumulation of ash and the formation of carbonate and organic anion during high-temperature pyrolysis process. Moreover, the prepared samples were analyzed by different characterization techniques including BET, SEM, and XPS. Adsorption experiments using the optimized biochar sample of SBC800 resulted in a 95% sulfamethoxazole (SMX) removal efficiency and the maximum adsorption capacity of 7033.4 mg/kg, which was 47.5 times higher than that of SBC300. The adsorption process of SBC800 for SMX was more in line with the Freundlich and D-A isotherm model, the whole process was an exothermic reaction. SBC800 could effectively remove SMX through pore filling effect, electrostatic attraction, hydrogen bonding, hydrophobic effect, and π-π EDA interaction. Site energy distribution analysis showed that SMX preferentially occupied the high-energy adsorption site of SBC800, and then gradually diffused to the low-energy adsorption site. This study proposed a sustainable method for recycling municipal sludge for organic pollutant removal.

The fate of sulfamethoxazole and trimethoprim in a micro-aerated anaerobic membrane bioreactor and the occurrence of antibiotic resistance in the permeate.

This study investigates the effects, conversions, and resistance induction, following the addition of 150 μg·L-1 of two antibiotics, sulfamethoxazole (SMX) and trimethoprim (TMP), in a laboratory-scale micro-aerated anaerobic membrane bioreactor (MA-AnMBR). TMP and SMX were removed at 97 and 86%, indicating that micro-aeration did not hamper their removal. These antibiotics only affected the pH and biogas composition of the process, with a significant change in pH from 7.8 to 7.5, and a decrease in biogas methane content from 84 to 78%. TMP was rapidly adsorbed onto the sludge and subsequently degraded during the long solids retention time of 27 days. SMX adsorption was minimal, but the applied hydraulic retention time of 2.6 days was sufficiently long to biodegrade SMX. The levels of three antibiotic-resistant genes (ARGs) (sul1, sul2, and dfrA1) and one mobile genetic element biomarker (intI1) were analyzed by qPCR. Additions of the antibiotics increased the relative abundances of all ARGs and intI1 in the MA-AnMBR sludge, with the sul2 gene folding 15 times after 310 days of operation. The MA-AnMBR was able to reduce the concentration of antibiotic-resistant bacteria (ARB) in the permeate by 3 log.

The role of biochar and green compost amendments in the adsorption, leaching, and degradation of sulfamethoxazole in basic soil

The fate of the antibiotic sulfamethoxazole in amended soils remains unclear, moreover in basic soils. This work aimed to assess the adsorption, leaching, and biodegradation of sulfamethoxazole in unamended and biochar from holm oak pruning (BC)- and green compost from urban pruning (CG)-amended basic soil. Adsorption properties of the organic amendments and soil were determined by adsorption isotherms of sulfamethoxazole. The leachability of this antibiotic from unamended (Soil) and BC- (Soil + BC) and GC- (Soil + GC) amended soil was determined by leaching columns using water as solvent up to 250 mL. Finally, Soil, Soil + BC, and Soil + GC were spiked with sulfamethoxazole and incubated for 42 days. The degradation rate and microbial activity were periodically monitored. Adsorption isotherms showed poor adsorption of sulfamethoxazole in unamended basic soil. BC and CG showed good adsorption capacity. Soil + BC and Soil + GC increased the sulfamethoxazole adsorption capacity of the soil. The low sulfamethoxazole adsorption of Soil produced quick and intense sulfamethoxazole leaching. Soil + BC reduced the sulfamethoxazole leaching, unlike to Soil + GC which enhanced it concerning Soil. The pH of adsorption isotherms and leachates indicate that the anion of sulfamethoxazole was the major specie in unamended and amended soil. CG enhanced the microbial activity of the soil and promoted the degradability of sulfamethoxazole. In contrast, the high adsorption and low biostimulation effect of BC in soil reduced the degradation of sulfamethoxazole. The half-life of sulfamethoxazole was 2.6, 6.9, and 11.9 days for Soil + GC, Soil, and Soil + BC, respectively. This work shows the benefits and risks of two organic amendments, BC and GC, for the environmental fate of sulfamethoxazole. The different nature of the organic carbon of the amendments was responsible for the different effects on the soil.