Adsorption Of Sulfamethoxazole Research Articles

Multifunctional Copper Sulfide Urchin‐Like Nanostructures for Adsorption and Photocatalysis of Water Contaminants

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

Surface-Adhered Microbubbles Enhance the Resistance of ANAMMOX Granular Sludge to Sulfamethoxazole Stress.

The granule-based anammox process has been reported to be more resistant to the stress of antibiotics; however, the underlying resistance mechanism is still not fully understood. In this study, we found that more microbubbles stably adhered to the surface layer of anammox granular sludge (AnGS, Gs) operating under long-term sulfamethoxazole (SMZ) stress of 2 mg/L, compared to that in the control reactor (Gc). The difference in covering content can be up to over three times (1.0 ± 0.1% vs 0.3 ± 0.0%). Batch tests showed that the coverage ratio of microbubbles on Gs reached approximately 32.5%, which significantly reduced SMZ transfer into AnGS due to the adsorption of SMZ by bubbles, thus alleviating the inhibition of anammox bacterial activity by 36.5%. The adhesion force between the microbubbles and the surface layer of Gs was found to be largely enhanced by 75.0% compared to that of Gc. The increased hydrophobicity of surface layer due to the increased extracellular polymer substance (EPS, mainly proteins) content, and the larger capillary force of surface layer, owing to the unique micronano structure, were identified as key factors responsible for the stable adhesion of microbubbles on the Gs. Consequently, this study demonstrated the vital roles of the surface-adhered microbubbles in resisting the stress of SMZ and shed light on the regulation and development of robust granule-based anammox processes.

Competitive adsorption of oxytetracycline and sulfamethoxazole by nanosized activated carbon in aquatic environments: Experimental analysis and DFT calculations

Nanosized activated carbon (NAC) is an emerging carbonaceous nanomaterial for water treatment, while oxytetracycline (OTC) and sulfamethoxazole (SMX) coexisting in aquatic environments may undergo competitive adsorption to influence its removal efficiency. This study investigated the competitive adsorption of OTC and SMX onto NAC under different interaction sequence, pH, electrolyte, and water matrix conditions, using experimental analysis and density function theory (DFT) calculations. Adsorption kinetics show that increasing concentration of one antibiotic inhibited the adsorption of another. Faster equilibrium was attained in binary systems than single systems due to competitive adsorption, with pseudo-second-order model providing the best fit in both systems. Adsorption isotherms suggest that NAC exhibited stronger affinity towards OTC (395.26 mg/g) than SMX (232.02 mg/g), with Langmuir model showing satisfactory fitting in both single and binary systems. Sequential adsorption of [NAC + OTC] + SMX was more favored than binary adsorption, aligning with the optimum configuration of SMX--[NAC-OTC±] with binding energy of −57.25 kcal/mol from DFT calculations. Competitive adsorption was preferred within pH 3.2–5.6, where electrostatic attraction existed between NAC and cationic antibiotics. Salting-out, charge screening, and complexation effects from Na+ and Ca2+ influenced competitive adsorption. Optimal removal of OTC and SMX by NAC was achieved in wastewater effluent among four water matrices in both single and binary systems. Hydrogen bonding, π − π electron donor–acceptor interactions, electrostatic interactions, and hydrophobic interactions contributed to adsorption. Sequential change in functional groups of NAC followed − OH → C − H → C − O → C = C and C = C → C − O → C − H → − OH in single and binary systems, respectively. The findings provide valuable insights into the competitive adsorption mechanisms of antibiotics on NAC, highlighting its potential for remediating mixtures of antibiotics in complex aquatic environments.

Pyrolytic conversion of cattle manure into value-added products and application of biochar for adsorption of sulfamethoxazole

This study investigated the thermochemical conversion of cattle manure (CM) to propose a sustainable platform for its valorization, and explored the applicability of CM-derived biochar (CMB) as an environmental medium for the adsorptive removal of sulfamethoxazole (SMZ). CM pyrolysis was conducted under two atmospheric conditions (N2 and CO2), and the pyrogenic products were quantified and characterized. Real-time syngas monitoring revealed that CO2 enhanced CO generation from the CM, leading to the formation of a highly porous carbon structure in the produced biochar (CMBCO2). The adsorptive removal of SMZ by CMBCO2 was highly dependent on the pH conditions. The adsorption kinetics of SMZ onto CMBCO2 reached equilibrium within 540min, following a pseudo-second-order model. The SMZ adsorption isotherms fit the Langmuir-Freundlich model, highlighting the importance of chemisorption in the adsorption process. X-ray photoelectron spectroscopy revealed that SMZ was adsorbed by non-electrostatic mechanisms, including hydrogen bonding, Lewis acid-base interactions, surface complexation, and π-π electron-donor acceptor interactions. This study presents an exemplary strategy for converting livestock waste into valuable resources, enabling the harvesting of energy resources and the production of treatment media for environmental remediation.

Investigation of mechanisms of sulfamethoxazole adsorption on novel adsorbents developed from reed canary grass

In this work, reed canary grass and activated carbons developed from this biomass were used as novel adsorbents to remove sulfamethoxazole (SMX) from water. Raw biomass adsorbent with the lowest surface area demonstrated the lowest SMX adoption capacity of 20.2 ± 1.6 mg/g and the activated carbon adsorbent with the highest surface area showed the highest adsorption capacity of 160.5 ± 4.2 mg/g. π-π, hydrogen bonding, Lewis acid base, and hydrophobic interactions are the possible mechanisms that could be responsible for adsorption of SMX on the adsorbents. Methanol, hydrochloric acid solution, sodium hydroxide solution, and deionized water were used to desorb SMX from the adsorbent. The results of using 20 mL of solvent at 35 °C showed that methanol could desorb loaded SMX with a higher desorption efficiency (80.1 ± 2%) than the aqueous solvents (9.5-46.5%). Decreasing the temperature to 25 °C decreased the desorption efficiency of methanol to 58.5 ± 1%. By decreasing the methanol volume to 5 mL, SMX desorption efficiency could remain comparable (59.1 ± 1.2%). Reusing the adsorbent in 4 adsorption desorption cycles showed that SMX adsorption capacity reduced from 124.9 ± 3.8 mg/g in the first adsorption cycle to 82.1 ± 2.2 mg/g in the second adsorption cycle and was stable in the third and fourth cycles.

Adsorption of sulfamethoxazole and ciprofloxacin on chitosan foam: Isotherms modeling and binding mechanisms

The paper investigates the adsorption of two pharmaceutical compounds (PCs) from polluted water, namely sulfamethoxazole (STZ) and ciprofloxacin (CRA), onto a new adsorbent formed by dispersion of chitosan on polyurethane (PU/C). Adsorption isotherms were determined on the investigated adsorbent as a function of temperature, in the range 298–328 K. For each temperature, PU/C showed higher affinity toward STZ with a maximum adsorption capacity at the maximum investigated temperature. A double-layer model was adopted for the interpretation of the entire adsorption data set. The number of adsorbate molecules bound per active site allowed for determining that an aggregation process occurs upon adsorption. The retrieved values for the CRA- PU/C system are 1.37, 1.61, 1.68, and 0.606 at 298, 308, 318, and 328 K, respectively, while for the STZ- PU/C system, the corresponding values are 0.76, 1.07, 1.23 and 1.36 at T = 298, 308, 318 and 328 K respectively. Finally, the values of adsorption energy define the phenomenon under investigation as a physisorption.

Surface coupling of molecularly imprinted polymers as strategy to improve sulfamethoxazole removal from water by carbons produced from spent brewery grain

This work aims to assess the surface coupling of molecularly imprinted polymers (MIP) on carbon adsorbents produced from spent brewery grain, namely biochar (BC) and activated carbon (AC), as a strategy to improve selectivity and the adsorptive removal of the antibiotic sulfamethoxazole (SMX) from water. BC and AC were produced by microwave-assisted pyrolysis, and MIP was obtained by fast bulk polymerization. Two different methodologies were used for the molecular imprinting of BC and AC, the resulting materials being tested for SMX adsorption. Then, after selecting the most favourable molecular imprinting methodology, different mass ratios of MIP:BC or MIP:AC were used to produce and evaluate eight different materials. Molecular imprinting was shown to significantly improve the performance of BC for the target application, and one of the produced composites (MIP1-BC-s(1:3)) was selected for further kinetic and equilibrium studies and comparison with individual MIP and BC. The kinetic behaviour was properly described by both the pseudo-first and pseudo-second order models. Regarding equilibrium isotherms, they fitted the Freundlich and Langmuir models, with MIP1-BC-s(1:3) reaching a maximum adsorption capacity (qm) of 25 ± 1 μmol g-1, 19 % higher than BC. In comparison with other seven pharmaceuticals, the adsorption of SMX onto MIP1-BC-s(1:3) was remarkably higher, as for the specific recognition of this antibiotic by the coupled MIP. The pH study evidenced that SMX removal was higher under acidic conditions. Regeneration experiments showed that MIP1-BC-s(1:3) provided good adsorption performance, which was stable during five regeneration-reutilization cycles. Overall, this study has demonstrated that coupling with MIP may be a suitable strategy to improve the adsorption properties and performance of biochar for antibiotics removal from water, increasing its suitability for practical applications.

Coadsorption mechanisms of copper and sulfamethoxazole by functionalized cellulose: A kinetic and DFT study

In order to address the issue of compound pollution from heavy metals and antibiotics in aquatic environments, multibranched functionalized cellulose materials (DACS) with abundant adsorption affinity groups (such as amino, carboxyl and imine groups) were prepared by oxidation, etherification and grafting. The maximum adsorption capacities of DACS for copper (Cu) and sulfamethoxazole (SMZ) were 42.27 and 117.92 mg/g, respectively. In addition, its excellent pH buffering capacity, resistance to coexisting interfering substances and great regeneration performance of up to 91 % after 5 cycles. In the coadsorption experiment, the multibranched structure strengthened the bridge effect during the coadsorption process, and weakened the inhibition of SMZ adsorption caused by competition. Kinetic models and error functions analysis showed that PNO model and F&S model were the most consistent with the adsorption process, and the limiting step of adsorption was the external diffusion of Cu and SMZ around the surface of DACS. Moreover, the density functional theory (DFT) was used to quantitatively calculate the adsorption binding energy of multiple sites on DACS, and clarified the adsorption tendency of DACS as electron donors for Cu and as acceptor for SMZ. In addition, the binding energy of sequential adsorption was greater than that of single and binary adsorption, and the binding stability of SMZ was significantly increased in sequential adsorption for the increasing of binding energy. The electron exchange process in the adsorption showed that SMZ played a bridging role in the binary adsorption, while Cu was the main reaction part of the complex adsorption.

Prosopis juliflora biochar for adsorption of sulfamethoxazole and ciprofloxacin from pharmaceutical wastewater

This study aimed to synthesize the biochar of Prosopis juliflora (PJ) and apply it to the adsorption of antibiotic residues sulfamethoxazole (SMZ) and ciprofloxacin (CIX) from pharmaceutical industry wastewater. The PJ biochar was synthesized using the pyrolysis method and characterized by proximate analysis, TGA, SEM-EDX, FTIR, XRD, and BET methods. The moisture content, volatile matter, ash content, and fixed carbon were found to be 6.4 %, 72.3 %, 3.0 %, and 18.3 %, respectively. Moreover, biochar characteristics were described by a high BET surface area of 875 m2/g, various FTIR peaks with different functional groups, high TGA thermal stability at increasing temperature, amorphous XRD structure, and high SEM surface morphology, and major EDX carbon compositions of 97 %. These analysis results demonstrated insights into the potential and nature of biochar adsorbent. The maximum adsorption of SMZ and CIX was found to be 98.7 % and 97.8 %, respectively, at a contact time of 120 min, initial concentration of 50 mg/L, pH (5 for CIX and 8 for SMZ), and adsorbent dose of 1 g/L for a synthetic solution. On the other hand, COD and TOC of real wastewater were reduced from 2498 to 514 mg/L and 1050 to 124 mg/L during the real wastewater treatment. Target pollutants concentration in real wastewater was found to be 8.29 and 5.3 mg/L for CIX and SMZ and their removal efficiency was obtained as 80.4 % and 76.7 % respectively. The obtained experimental data were best fitted with the Langmuir isothermal model at R2 = 0.999, implying the adsorbent surface is homogeneous and monolayer. Similarly, the adsorption kinetics process was well described by a pseudo-second-order kinetics model for both SMZ and CIX at R² = 0.999. Finally, the non-linear intra-particle diffusion graphs suggest that chemical adsorption is the main influencing factor for overall kinetics. In conclusion, using PJ biochar is a promising precursor in advancing adsorbents for removing contaminants from industrial wastewater to address environmental pollution challenges.

Evaluation and analysis of the adsorption mechanism of three emerging pharmaceutical pollutants on a phosphorised carbon-based adsorbent: Application of advanced analytical models to overcome the limitation of classical models

The double layer adsorption of sulfamethoxazole, ketoprofen and carbamazepine on a phosphorus carbon-based adsorbent was analyzed using statistical physics models. The objective of this research was to provide a physicochemical analysis of the adsorption mechanism of these organic compounds via the calculation of both steric and energetic parameters. Results showed that the adsorption mechanism of these pharmaceuticals was multimolecular where the presence of molecular aggregates (mainly dimers) could be expected in the aqueous solution. This adsorbent showed adsorption capacities at saturation from 15 to 36 mg/g for tested pharmaceutical molecules. The ketoprofen adsorption was exothermic, while the adsorption of sulfamethoxazole and carbamazepine was endothermic. The adsorption mechanism of these molecules involved physical interaction forces with interaction energies from 5.95 to 19.66 kJ/mol. These results contribute with insights on the adsorption mechanisms of pharmaceutical pollutants. The identification of molecular aggregates, the calculation of maximum adsorption capacities and the characterization of thermodynamic behavior provide crucial information for the understanding of these adsorption systems and to optimize their removal operating conditions. These findings have direct implications for wastewater treatment and environmental remediation associated with pharmaceutical pollution where advanced adsorption technologies are required.

Preparation of iota-carrageenan@bentonite@4-phenyl-3-thiosemicarbazide ternary hydrogel for adsorption of Losartan potassium and sulfamethoxazole

A rising quantity of drugs has been discharged into the aquatic environment, posing a substantial hazard to public health. In the current work, a novel hydrogel (i.Carr@Bent@PTC), comprised of iota-carrageenan, bentonite, and 4-phenyl-3-thiosemicarbazide, was successfully prepared. The introduction of 4-phenyl-3-thiosemicarbazide and bentonite in iota-carrageenan significantly increased the mechanical strength of iota-carrageenan hydrogel and improved its degree of swelling, which can be attributed to the hydrophilic properties of PTC and Bent. The recorded contact angle was 70.8°, 59.1°, 53.9°, and 34.6° for pristine i.Carr, i.Carr@Bent, and i.Carr@Bent@PTC, respectively. The low contact angle measurement of the Bent and PTC loaded-i.Carr hydrogel was attributed to the hydrophilic Bent and PTC. The ternary i.Carr@Bent@PTC hydrogel demonstrated broad pH adaptability and excellent adsorption capacities for sulfamethoxazole (SMX) and losartan potassium (LP), i.e., 467.61 mg. g−1 and 274.43 mg. g−1 at 298.15 K, respectively. The pseudo-first-order (PSO) model provided a better fit for the adsorption kinetics. The adsorption of SMX and LP can be better explained by employing the Sips and Langmuir isotherm models. As revealed by XPS and FTIR investigations, π-π stacking, complexation, electrostatic interaction, and hydrogen bonding were primarily involved in the adsorption mechanisms.

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.

Valorization of agricultural olive waste as an activated carbon adsorbent for the remediation of water sources contaminated with pharmaceuticals

The present study investigates the performance of activated carbon from olive pomace (ACOP) in the removal of hydrophilic organic pharmaceutical micropollutants such as the antibiotic sulfamethoxazole (SMX) from water. The adsorption behavior of two chemically modified ACOP was investigated considering their interesting textural properties, relevant surface functions and charges. The performances in terms of adsorption capacity were investigated and optimized with respect to the main operating conditions. Comparison of SMX adsorption capacities on ACOP with commercial powdered activated carbon and nanoporous carbonaceous materials prepared from argan shells revealed that ACOP enabled the highest adsorption capacities (39.68 mg g−1). The adsorption behavior was attributed not only to the textural properties, such as the large surface area (1857 m2 g−1) and porosity, but also to the charge and functional groups of the surface.

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 10 wt% 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 (46.69 mg.g−1) and for SDM in non-saline water (107.69 mg.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.

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.