Nano-sized magnetic molecularly imprinted polymer solid-phase microextraction for highly selective recognition and enrichment of sulfamethoxazole from spiked water samples.

This research, described ultrasound-assisted dispersive magnetic solid-phase microextraction, which is efficient for the enrichment and determination of sulfamethoxazole, based on magnetic molecularly imprinted polymer (USA-DMSPME-MIP). Meanwhile, the initial characterization of Fe3O4-MIP was completed by conventional methods and well-known protocols to obtain recognition and adsorbing performance at pre-specified optimum conditions. Fe3O4-MIP exhibited information regarding its selective recognition pattern towards sulfamethoxazole. The USA-DMSPME-MIP parameters were optimized by response surface methodology, and based on optimum conditions, this efficient method for the extraction and enrichment of sulfamethoxazole from spiked water samples and quantification by HPLC-UV was used. The enhanced technique indicates the limit of detection is 2 ng mL-1 for sulfamethoxazole, along with excellent linear range with coefficients of determination >0.99 and good recoveries for spiked water samples (94.2 and 98.2 %) with RSDs less than 3.5 %.

Preliminary insights on the development of a continuous-flow solar system for the photocatalytic degradation of contaminants of emerging concern in water.

The ubiquity and impact of pharmaceuticals and pesticides, as well as their residues in environmental compartments, particularly in water, have raised human and environmental health concerns. This emphasizes the need of developing sustainable methods for their removal. Solar-driven photocatalytic degradation has emerged as a promising approach for the chemical decontamination of water, sparking intensive scientific research in this field. Advancements in photocatalytic materials have driven the need for solar reactors that efficiently integrate photocatalysts for real-world water treatment. This study reports preliminary results from the development and evaluation of a solar system for TiO2-based photocatalytic degradation of intermittently flowing water contaminated with doxycycline (DXC), sulfamethoxazole (SMX), dexamethasone (DXM), and carbendazim (CBZ). The system consisted of a Fresnel-type UV solar concentrator that focused on the opening and focal point of a parabolic trough concentrator, within which tubular quartz glass reactors were fixed. Concentric springs coated with TiO2, arranged one inside the other, were fixed inside the quartz reactors. The reactors are connected to a raw water tank at the inlet and a check valve at the outlet. Rotating wheels at the collector base enable solar tracking in two axes. The substances (SMX, DXC, and CBZ) were dissolved in dechlorinated tap water at a concentration of 1.0 mg/L, except DXM (0.8 mg/L). The water underwent sequential batch (~ 3 L each, without recirculation) processing with retention times of 15, 30, 60, 90, and 120 min. After 15 min, the degradation rates were as follows: DXC 87%, SMX 35.5%, DXM 32%, and CBZ 31.8%. The system processed 101 L of water daily, simultaneously removing 870, 355, 256, and 318 µg/L of DXC, SMX, DXM, and CBZ, respectively, showcasing its potential for real-world chemical water decontamination application. Further enhancements that enable continuous-flow operation and integrate highly effective adsorbents and photocatalytic materials can significantly enhance system performance.

Transport of Carbamazepine, Ciprofloxacin and Sulfamethoxazole in Activated Carbon: Solubility and Relationships between Structure and Diffusional Parameters.

The transport of carbamazepine, ciprofloxacin and sulfamethoxazole in the different pores of activated carbon in an aqueous solution is a dynamic process that is entirely dependent on the intrinsic parameters of these molecules and of the adsorbent. The macroscopic processes that take place are analyzed by interfacial diffusion and reaction models. Modeling of the experimental kinetic curves obtained following batch treatment of each solute at 2 µg/L in tap water showed (i) that the transport and sorption rates were controlled by external diffusion and intraparticle diffusion and (ii) that the effective diffusion coefficient for each solute, with the surface and pore diffusion coefficients, were linked by a linear relationship. A statistical analysis of the experimental data established correlations between the diffusional parameters and some geometrical parameters of these three molecules. Given the major discontinuities observed in the adsorption kinetics, the modeling of the experimental data required the use of traditional kinetic models, as well as a new kinetic model composed of the pseudo first or second order model and a sigmoidal expression. The predictions of this model were excellent. The solubility of each molecule below 60 °C was formulated by an empirical expression.

Removal of Persistent Sulfamethoxazole and Carbamazepine from Water by Horseradish Peroxidase Encapsulated into Poly(Vinyl Chloride) Electrospun Fibers.

Enzymatic conversion of pharmaceutically active ingredients (API), using immobilized enzymes should be considered as a promising industrial tool due to improved reusability and stability of the biocatalysts at harsh process conditions. Therefore, in this study horseradish peroxidase was immobilized into sodium alginate capsules and then trapped into poly(vinyl chloride) electrospun fibers to provide additional enzyme stabilization and protection against the negative effect of harsh process conditions. Due to encapsulation immobilization, 100% of immobilization yield was achieved leading to loading of 25 µg of enzyme in 1 mg of the support. Immobilized in such a way, enzyme showed over 80% activity retention. Further, only slight changes in kinetic parameters of free (Km = 1.54 mM) and immobilized horseradish peroxidase (Km = 1.83 mM) were noticed, indicating retention of high catalytic properties and high substrate affinity by encapsulated biocatalyst. Encapsulated horseradish peroxidase was tested in biodegradation of two frequently occurring in wastewater API, sulfamethoxazole (antibiotic) and carbamazepine (anticonvulsant). Over 80% of both pharmaceutics was removed by immobilized enzyme after 24 h of the process from the solution at a concentration of 1 mg/L, under optimal conditions, which were found to be pH 7, temperature 25 °C and 2 mM of H2O2. However, even from 10 mg/L solutions, it was possible to remove over 40% of both pharmaceuticals. Finally, the reusability and storage stability study of immobilized horseradish peroxidase showed retention of over 60% of initial activity after 20 days of storage at 4 °C and after 10 repeated catalytic cycles, indicating great practical application potential. By contrast, the free enzyme showed less than 20% of its initial activity after 20 days of storage and exhibited no recycling potential.

Sulfamethoxazole Removal from Drinking Water by Activated Carbon: Kinetics and Diffusion Process.

Sulfamethoxazole (SMX), a pharmaceutical residue, which is persistent and mobile in soils, shows low biodegradability, and is frequently found in the different aquatic compartments, can be found at very low concentrations in water intended for human consumption. In conditions compatible with industrial practices, the kinetic reactivity and performance of tap water purification using activated carbon powder (ACP) are examined here using two extreme mass ratios of SMX to ACP: 2 µg/L and 2 mg/L of SMX for only 10 mg/L of ACP. In response to surface chemistry, ACP texture and the intrinsic properties of SMX in water at a pH of 8.1, four kinetic models, and two monosolute equilibrium models showed a total purification of the 2 µg/L of SMX, the presence of energetic heterogeneity of surface adsorption of ACP, rapid kinetics compatible with the residence times of industrial water treatment processes, and kinetics affected by intraparticle diffusion. The adsorption mechanisms proposed are physical mechanisms based mainly on π-π dispersion interactions and electrostatic interactions by SMX-/Divalent cation/ArO- and SMX-/Divalent cation/ArCOO- bridging. Adsorption in tap water, also an innovative element of this study, shows that ACP is very efficient for the purification of very slightly polluted water.

Magnetically separable Fe-MIL-88B_NH2 carbonaceous nanocomposites for efficient removal of sulfamethoxazole from aqueous solutions.

Extensive exposure to antibiotics could potentially be harmful to the environment and human health. The development of effective and convenient technologies to remove residual antibiotics from water is imperative. Herein, we successfully developed a facile method via pyrolysis of Fe-MIL-88B_NH2 to synthesize magnetic nanocomposites (MNC) as potential adsorbents, which exhibited cluster-shape structure and excellent magnetic response. Magnetic nanocomposites carbonized at 700 °C showed high efficiency for sulfamethoxazole (SMX) adsorption (73.53 mg/g). Some experimental conditions including solution pH, ionic strength, coexisting ions and SMX concentration were systematically investigated. The adsorption isotherm and kinetic followed Langmuir and the pseudo-second-order models, and the adsorption process was dependent on the solution pH. The adsorption mechanism hypothesis was pore filling effect, π-π EDA and electrostatic interactions. Moreover, MNC-700 exhibited good reusability and magnetic separation properties, being reused six times without significant loss in adsorption capacity.

Competitive adsorption of tylosin, sulfamethoxazole and Cu(II) on nano-hydroxyapatitemodified biochar in water.

Antibiotics and heavy metals are frequently detected simultaneously in water environment. In this study, the competitive adsorption behavior of tylosin (TYL) and sulfamethoxazole (SMX) on nano-hydroxyapatite modified biochar (nHAP@biochar) in accordance with Cu(II) in single, binary and ternary systems was investigated. The specific surface area of nHAP@biochar was 566.056 m2/g. The adsorption of TYL on nHAP@biochar reduced by 13.36%-41.04% or 9.92%-38.69% with Cu(II) and SMX in the solution, respectively. The suppression of SMX was stronger than Cu(II) on the adsorption of TYL when the SMX or Cu(II) was constant. The adsorption of SMX increased by 2.01-3.56 times in the present of Cu(II), while suppressed by TYL up to 42.30%. Due to the bridging of TYL or SMX between the nHAP@biochar and Cu(II) and destroying of bound water surrounded, the adsorption of Cu(II) increased to a greater extent. Electrostatic interaction and H-bond were the two main interactions between TYL, SMX and Cu(II) and nHAP@biochar. π-π interactions was also interaction between the SMX and nHAP@biochar.

Removal and biotransformation pathway of antibiotic sulfamethoxazole from municipal wastewater treatment by anaerobic membrane bioreactor.

A lab-scale mesophilic anaerobic membrane bioreactor (AnMBR) was used to treat synthetic municipal wastewater with variable concentrations of antibiotic Sulfamethoxazole (SMX) and bulk organics in this study. The removal and biotransformation pathway of SMX in the AnMBR were systematically investigated during a 170 d of operation under hydraulic retention time of 1 d. Average SMX removal was 97.1% under feed SMX of 10-1000 µg/L, decreasing to 91.6 and 88.0% under feed SMX of 10,000 and 100,000 µg/L due to the inhibition effects of high SMX loading rate on anaerobic microorganisms. SMX biotransformation followed pseudo-first order reaction kinetics based on SMX removal independent of feed SMX of 10-1000 µg/L during continuous operation and also in a batch test under initial SMX of 100,000 µg/L. According to the identified 7 transformation products (TPs) by gas chromatography-mass spectrometry, the biotransformation pathway of SMX from municipal wastewater treatment via AnMBR was first proposed to consist of 2 primary routes: 1) Butylbenzenesulfonamide without antibiotic toxicity dominated under feed SMX of 10-100 µg/L; 2) Sulfanilamide with much lower antibiotic toxicity than SMX dominated under feed SMX of 1000-100000 µg/L, further transforming to secondary TPs (4-Aminothiophenol, Aniline, Acetylsulfanilamide) and tertiary TPs (4-Acetylaminothiophenol, Acetylaniline).

Study of the adsorption of endocrine disruptor compounds on typical filter materials using a quartz crystal microbalance.

Drinking water containing environmental endocrine disruptor compounds (EDCs) endangers human health, and researching the purification process of drinking water for the effective removal of EDCs is vitally important. Filtering plays a crucial role in the bio-adsorption of EDCs, but the adsorption mechanism that occurs between the EDCs and filters remains unclear. In this study, a quartz crystal microbalance (QCM) was employed to elucidate the adsorption mechanism because QCM is a label-free method that possesses high selectivity, high stability, and high sensitivity. The results indicated that a pseudo-first-order kinetic model best fits the adsorption process of four different EDCs, which included bisphenol A (BPA), estrone (E1), estradiol (E2), and sulfamethoxazole (SMZ), on silica (quartz sand), a typical filter material surface. The order of the amount of individual EDCs absorbed on the silica surface was qE2 > qE1 > qSMZ > qBPA and related to their molecular structure, polarity, and chargeability. As the initial EDC concentration increased, the adsorbed amount of the four EDCs on the silica surface increased; however, the initial concentration had little effect on removal efficiency. The calculated Freundlich exponent (1/n) demonstrated SMZ and BPA showed a greater tendency for adsorption than E1 and E2. The mass response time on the surface of the silica gradually increased as the pH increased (from 5.5 to 8.5), indicating the adsorption rate was inhibited by the increase in pH. The addition of electrolytes shortened the mass response time of EDCs on the QCM chip. The pH and ionic strength produced no significant effects on adsorption because hydrophobicity was the primary contributor to adsorption. This study facilitated a better understanding of the interaction between EDCs and filters in water treatment.

Removal of Sulfamethoxazole, Sulfathiazole and Sulfamethazine in their Mixed Solution by UV/H2O2 Process.

Sulfamethoxazole (SMZ), sulfathiazole (STZ) and sulfamethazine (SMT) are typical sulfonamides, which are widespread in aqueous environments and have aroused great concern in recent years. In this study, the photochemical oxidation of SMZ, STZ and SMT in their mixed solution using UV/H2O2 process was innovatively investigated. The result showed that the sulfonamides could be completely decomposed in the UV/H2O2 system, and each contaminant in the co-existence system fitted the pseudo-first-order kinetic model. The removal of sulfonamides was influenced by the initial concentration of the mixed solution, the intensity of UV light irradiation, the dosage of H2O2 and the initial pH of the solution. The increase of UV light intensity and H2O2 dosage substantially enhanced the decomposition efficiency, while a higher initial concentration of mixed solution heavily suppressed the decomposition rate. The decomposition of SMZ and SMT during the UV/H2O2 process was favorable under neutral and acidic conditions. Moreover, the generated intermediates of SMZ, STZ and SMT during the UV/H2O2 process were identified in depth, and a corresponding degradation pathway was proposed.

Trimethyl Chitosan/Siloxane-Hybrid Coated Fe3O4 Nanoparticles for the Uptake of Sulfamethoxazole from Water.

The presence of several organic contaminants in the environment and aquatic compartments has been a matter of great concern in the recent years. To tackle this problem, new sustainable and cost-effective technologies are needed. Herein we describe magnetic biosorbents prepared from trimethyl chitosan (TMC), which is a quaternary chitosan scarcely studied for environmental applications. Core@shell particles comprising a core of magnetite (Fe3O4) coated with TMC/siloxane hybrid shells (Fe3O4@SiO2/SiTMC) were successfully prepared using a simple one-step coating procedure. Adsorption tests were conducted to investigate the potential of the coated particles for the magnetically assisted removal of the antibiotic sulfamethoxazole (SMX) from aqueous solutions. It was found that TMC-based particles provide higher SMX adsorption capacity than the counterparts prepared using pristine chitosan. Therefore, the type of chemical modification introduced in the chitosan type precursors used in the surface coatings has a dominant effect on the sorption efficiency of the respective final magnetic nanosorbents.

Laccase removal of 2-chlorophenol and sulfamethoxazole in municipal wastewater.

Laccases were studied for their ability to remove two compounds, 2-chlorophenol and sulfamethoxazole, in batch studies, both in buffered solutions and in wastewater samples from different points in a municipal water resource recovery facility. Two enzymes with and without a mediator (acetosyringone) were investigated: a commercial product derived from Myceliphthora thermophile and a laboratory-generated enzyme mix derived from Tramates versicolor. The chlorophenol was removed rapidly by the commercial enzyme in the presence of acetosyringone, but the primary products were coupling complexes of the reactants. Excellent removal was achieved without acetosyringone by the natural enzyme mix. Sulfamethoxazole was poorly removed in all laboratory-generated chemically buffered solutions, but was very well removed, without the addition of mediators, in secondary effluent suspensions from a municipal water resource recovery facility. Mechanistic studies are still required, but the results suggest that treatment via direct addition of enzymes is feasible to remove recalcitrant compounds in municipal wastewater.

Preparation of phenyl-boronic acid polymer monolith by initiator-free ring-opening polymerization for microextraction of sulfamethoxazole and trimethoprim from animal-originated foodstuffs.

Boronate affinity materials are usually used for selective enrichment of cis-diol-containing compounds, mainly based on formation of pH-dependent cyclic ester between cis-diol and boronic acid. Recently, B-N coordination, or combined with hydrogen-bonding interaction, was employed as primary interaction for the extraction of nitrogen-containing compounds. However, there are no reports about the combination of hydrophobic (or π-π) interaction and B-N coordination for the extraction. Here, we prepared a novel hydrophobic phenyl-boronic acid polymer (PBAP) through initiator-free ring-opening polymerization. The adsorption experiment indicated that the PBAP could combine hydrophobic (or π-π) interaction and B-N coordination to enhance their adsorption capacity toward hydrophobic and nitrogen-containing compounds, for example sulfamethoxazole (SMX) and trimethoprim (TMP). In addition, the PBAP monolith synthesized in pipette tip was used as solid phase microextraction (SPME) sorbent with combination of ultra high performance liquid chromatography to extract and monitor SMX and TMP from animal-originated foodstuffs. The proposed method exhibited low limit of quantitation as 5.0 and 1.0 ng mL-1 for SMX and TMP, respectively. The recoveries at three spiked levels were between 92.4% to 100.5% for SMX, and 92.7% to 102.6% for TMP, with intra-day and inter-day relative standard deviations no more than 5.3% and 8.6%, respectively. These results well demonstrated that the combination of hydrophobic (or π-π) interaction and B-N coordination played an important role in the extraction of hydrophobic and nitrogen-containing compounds.

Effects of pyrolysis temperature on the physicochemical properties of alfalfa-derived biochar for the adsorption of bisphenol A and sulfamethoxazole in water.

The present study reports alfalfa (one of most abundant hays in U.S)-derived biochar for effective removal of emerging contaminants in water for the first time. The physicochemical properties of alfalfa-derived biochar (AF-BC) made at various pyrolysis temperatures were investigated, and correlated with the adsorption of bisphenol A (BPA) and sulfamethoxazole (SMX) in water. The increase in pyrolysis temperatures from 350 °C to 650 °C for the pyrolysis of AF led to a drastic increase in surface area and carbonization with the loss of functional groups. The AF-derived biochar made at 650 °C showed much higher adsorption capacities for BPA and SMX than those made at 350-550 °C, mainly owing to the hydrophobic and π-π interactions supported by its high surface area and degree of carbonization. The adsorption isotherms fitted the Freundlich for BPA and Temkin models for SMX well, respectively. The adsorption capacities of AF 650 for BPA and SMX were higher than those of other biochars but lower than those of commercial activated carbon. The pH-dependent desorption for AF 650 showed high efficiency for SMX, but low efficiency for BPA indicating needs for alternative regeneration methods for BPA.

Hierarchical magnetic petal-like Fe3O4-ZnO@g-C3N4 for removal of sulfamethoxazole, suppression of photocorrosion, by-products identification and toxicity assessment.

Herein, a petal-like photocatalyst, Fe3O4-ZnO@g-C3N4 (FZG) with different g-C3N4 to ZnO ratios was synthesized with hierarchical structure. The FZG1 photocatalyst, having the weight ratio of 1:1 for the initial urea and Fe3O4-ZnO (Fe-ZnO), presented the highest sulfamethoxazole (SMX) degradation rate of 0.0351 (min-1), which was 2.6 times higher than that of pristine ZnO. Besides the facile separation, the performance of photocatalyst was improved due to the function of iron oxide as an electron acceptor that reduced the electron/hole recombination rate. The coating of g-C3N4 on the Fe-ZnO surface not only acted as a protective layer for ZnO against photocorrosion, but it also enhanced the photocatalytic activity of the catalyst for SMX degradation through the heterojunction mechanism. By using the FZG1 photocatalyst, 95% SMX removal was obtained after 90 min reaction, while 47% COD and 30% TOC removal were achieved after 60 min treatment under a low energy-consuming UV lamp (10 W). Moreover, a substantial reduction in the solution toxicity was shown after the treatment, as compared with the SMX solution before treatment. The LC-HR-MS/MS analysis results showed that the concentration of most detected by-products produced after 90 min reaction by FZG1 was considerably lower than those obtained using other synthesized photocatalysts. By performing radical scavenging experiments, OH° radical was found to be the major reactive species. The FZG1 photocatalyst also displayed excellent reusability in five cycles and the leaching of zinc and iron ions was reduced by 54% and ∼100%, respectively, after coating Fe-ZnO with g-C3N4.

Simultaneous removal of ciprofloxacin, norfloxacin, sulfamethoxazole by co-producing oxidative enzymes system of Phanerochaete chrysosporium and Pycnoporus sanguineus.

Pycnoporus sanguineus could remove 98.5% ciprofloxacin (CIP), 96.4% norfloxacin (NOR), 100% sulfamethoxazole (SMX), and 100% their mixture through biotransformation within 2 d, while Phanerochaete chrysosporium could only remove 64.5% CIP, 73.2% NOR, and 63.3% SMX through biosorption and biotransformation within 8 d, respectively. The efficiencies of antibiotic bioremoval under co-culture were more than that under the pure culture of P. chrysosporium but less than that under the pure culture of P. sanguineus. However, only 2% CIP and 3% NOR under co-culture were detected in the mycelia. In vitro enzymatic degradation and in vivo cytochrome P450 inhibition experiments revealed that laccase and cytochrome P450 could play roles in the removal of above all antibiotics, while manganese peroxidase could only play role in SMX removal. Transformation products of CIP and NOR under the pure culture of P. chrysosporium could be assigned to three different reaction pathways: (i) defluorination or dehydration, (ii) decarboxylation, and (iii) oxidation of the piperazinyl substituent. Additionally, other pathways, (iv) monohydroxylation, and (v) demethylation or deethylation at position N1 also occurred under the co-culture and pure culture of P. sanguineus. Antibacterial activity of antibiotics could be eliminated after treatments with pure and co-culture of P. chrysosporium and P. sanguineus. The cytotoxicity of the metabolites of SMX and NOR under co-culture was lower than that under the pure culture of P. sanguineus, indicating co-culture is a more environmentally friendly strategy to eliminate SMX and NOR.

Development of a soft extraction method for sulfamethoxazole and transformation products from agricultural soils: Effects of organic matter co-extraction on the environmental availability assessment.

The recycling of biosolids and livestock manure in agriculture may lead to the introduction of antibiotic residues, i.e., parent molecule and transformation products, into amended soils. Their fate in soils can be approached through the assessment of their environmental availability. In this work, the environmental availability of sulfamethoxazole (SMX) and three transformation products (N4-acetyl-SMX, 3-amino-5-methylisoxazole, aniline) was assessed in soils amended with sludge compost or cow manure throughout a three-month incubation, using soft extractions with CaCl2, EDTA or cyclodextrin solutions. First, the freeze-storage of soil samples was shown to decrease the SMX extractability. The SMX extractability depended on the initial concentration, the amendment type and the extracting solution at day 0. From 1.9% up to 63% of the SMX total content was initially extractable. The lowest fractions were quantified in EDTA extracts in which the dissolved organic matter was the most complex and responsible for high matrix effects in mass spectrometry compared to CaCl2 extracts. The purification of cyclodextrin extracts highly reduced the matrix effects, but CaCl2 was considered as the most suitable extractant. SMX extractability strongly decreased after the first 8days of incubation to finally reach 0.4-0.8% after 84days, whatever the initial conditions. This high decrease could be related to humification observed through the increasing complexity of extracted dissolved organic matter. Very low levels of transformation products were quantified throughout the incubation period. The low environmental availability of SMX was mainly due to its sorption on soil organic matter and resulted in its low biotransformation in these amended soils.

TiO2 supported on reed straw biochar as an adsorptive and photocatalytic composite for the efficient degradation of sulfamethoxazole in aqueous matrices.

Heterogeneous photocatalysis namely titanium dioxide supported on reed straw biochar (acid pre-treated) (TiO2/pBC) was synthesized by sol-gel method. The morphology, surface area and structure of TiO2/pBC were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD). Low calcination condition maintained the structure of biochar completely and prevented the agglomeration of TiO2 particles. Due to the combination of adsorption and photocatalysis, TiO2/pBC performed higher removal efficiency of sulfamethoxazole (SMX) than pure TiO2 powder under UV light irradiation. The photocatalytic degradation (PCD) of SMX was also studied with the water collected from the Yellow River. Three high concentration inorganic anions (Cl-, NO3-, SO42-) of the river exerted certain degree of detrimental effects on the contaminant degradation. TiO2/pBC showed stable photocatalytic activity after five sequential PCD cycles. The biochar was able to promote further PCD on TiO2 by adsorbing SMX and intermediates thereby prolonging the separation lifetime of electrons (e-) and valence band hole (h+). The transformation intermediates of SMX were identified and three possible degradation reactions of hydroxylation, opening of isoxazole ring and cleavage of SN bond might occur during the PCD of SMX.

Synthesis of magnetic biochar from pine sawdust via oxidative hydrolysis of FeCl2 for the removal sulfamethoxazole from aqueous solution.

Magnetisation of carbonaceous adsorbent using iron oxide (FexOy) has potential to decrease the recovery cost of spent adsorbent because it could be separated magnetically. However, formation of various phases of FexOy and iron hydroxide (Fex(OH)y) during synthesis particularly the non-magnetic phases are difficult to control and could significantly reduce the magnetic saturation of the adsorbent. Hence, formation of the most magnetic FexOy, Fe3O4, on biochar via oxidative hydrolysis of FeCl2 under alkaline media was performed to synthesise magnetic adsorbent using pine sawdust biochar (magnetic pine sawdust biochar: MPSB). The Fe3O4 nanoparticles on the surface of biochar contributed to high saturation magnetisation of MPSB, 47.8Am2/kg, enabling it to be separated from aqueous solution using a magnet. MPSB were examined physically and chemically using various techniques. Sorbent-stability, parametric, kinetics, isotherm, thermodynamic and sorbent-regeneration studies were performed to comprehend the potential of MPSB as adsorbent to remove an emerging contaminant, sulfamethoxazole (SMX) from aqueous solution. Results showed that MPSB was stable within solution pH 4-9. Adsorption of SMX onto MPSB was favourable at low pH, fast and best described by Redlich-Peterson model. Adsorption was exothermic with physisorption possibly due to hydrophobic interaction and spent adsorbent could be regenerated by organic solvents.

Effect of humic monomers on the adsorption of sulfamethoxazole sulfonamide antibiotic into a high silica zeolite Y: An interdisciplinary study.

The adsorption efficiency of a high silica zeolite Y towards sulfamethoxazole, a sulfonamide antibiotic, was evaluated in the presence of two humic monomers, vanillin and caffeic acid, representative of phenolic compounds usually occurring in water bodies, owing their dimension comparable to those of the zeolite microporosity. In the entire range of investigated pH (5-8), adsorption of vanillin, as a single component, was reversible whereas it was irreversible for sulfamethoxazole. In equimolar ternary mixtures, vanillin coadsorbed with sulfamethoxazole, conversely to what observed for caffeic acid, accordingly to their adsorption kinetics and pKa values. Lower and higher adsorptions were observed for sulfamethoxazole and vanillin, respectively, than what it was observed as single components, clearly revealing guest-guest interactions. An adduct formed through H-bonding between the carbonyl oxygen of vanillin and the heterocycle NH of sulfamethoxazole in amide form was observed in the zeolite pore by combined FTIR and Rietveld analysis, in agreement with Density Functional Theory calculations of the adduct stabilization energies. The formation of similar adducts, able to stabilize other naturally occurring phenolic compounds in the microporosities of hydrophobic sorbents, was proposed.