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In this study, straw residue (SR) was prepared from corn straw by a combined pre-treatment method that involved both microbial treatment (Myrothecium verrucaria, Aspergillus niger, and Trichoderma reesei) and treatment with ρ-toluenesulfonic acid. After pre-treatment, the cellulose content of the residues reached 79.3 %, 72.1 %, 83.5 %, and 85.2 %, respectively. The results indicated that Aspergillus niger and Trichoderma reesei effectively destroyed the corn stover structure, improving the efficiency of the subsequent treatment. Following carbonation and activation processes, the SRs were converted into a series of biochars (ACCC, ACMC, ACTC, and ACNC) with large specific surface areas (2343, 2219, 2693, 2672 m 2 g -1 ). The prepared biochars demonstrated excellent performance in adsorption tests performed using tetracycline hydrochloride (TC) and sulfadiazine sodium salt (SDZ) as adsorption models. The maximum adsorption capacities recorded for TC (908, 1117, 1216, and 1189 mg/g) and SDZ (930, 965, 1033, and 1083 mg/g) were higher than most of the other adsorbents. Furthermore, the potential adsorption mechanisms included pore filling, π-π interactions, hydrogen bonding, and electrostatic attraction. Even after 5 test cycles, the biochar retained over 75 % of its adsorption performance, highlighting its strong potential for applications in removing antibiotics from water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Contamination of aquatic products with sulfonamide antibiotics poses a threat to consumer health and can lead to the emergence of drug-resistant bacteria. Common methods to detect such compounds are slow and require expensive instruments. We developed a sensitive sulfadiazine (SDZ) detection method based on the photoinduced electron transfer between UCNPs and Cu 2+ . The surface-modified upconversion nanoparticles bind to Cu 2+ by electrostatic adsorption, causing fluorescence quenching. The quenched fluorescence was subsequently recovered by the addition of imidazole and SDZ to the detection system, which formed a complex with Cu 2+ . The sensor showed excellent linearity over a wide concentration range (0.05-1000 ng/mL), had a low limit of detection (0.04 ng/mL), was selective, and was not affected by common substances present in aquatic media. This indicates that the sensor has great potential for application in the detection of SDZ residues in aquatic products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The misuse of antibiotics may contaminate the environment and cause harm to human health. Therefore, rapid and accurate detection of antibiotics is essential. In this study, a novel electrochemiluminescence resonance energy transfer (ECL-RET) pair was designed using a new ECL emitter (CPM, Ce-TBAPy) as the donor and Co-MOF@AuPt as the acceptor. Moreover, a highly sensitive and specific "on-off-on" ECL aptasensor was constructed for detecting sulfadiazine (SDZ). The aptasensor exhibited a broad linear range (from 10.0 fg mL -1 to 100 ng mL -1 ) for the SDZ concentration, with limit of detection and limit of quantification values of 1.14 fg mL -1 and 3.75 fg mL -1 , respectively. The aptasensor achieved good results in spiking experiments with milk and egg samples, and successfully quantified SDZ in fish meal quality control sample. The prepared aptasensor presents great potential for food and environmental safety by detecting antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Heterogeneous catalyst-mediated sulfate radical-based advanced oxidation processes (SR-AOPs) showed excellent performance during antibiotics degradation. Spinel was a promising catalyst for SR-AOPs, but the secondary contamination due to metal ions leaching needed to be addressed. And the destruction of catalyst structure could lead to the reduction of catalytic activity and the difficulty of recovery. Thus, a novel nitrogen-doped carbon (NC)-supported CoFe 2 O 4 (CoFe 2 O 4 @NC) was synthesized as the activator of PMS for sulfadiazine (SDZ) degradation under low Co leaching conditions. The consequences indicated that the CoFe 2 O 4 @NC/PMS system exhibited higher PMS decomposition efficiency and reaction stoichiometry efficiency than the bare CoFe 2 O 4 /PMS systems (CoFe 2 O 4 -180 and CoFe 2 O 4 -800), which in turn demonstrated a better SDZ removal performance. Under the condition of CoFe 2 O 4 @NC dosage 0.1 g/L, PMS concentration 0.5 mM, solution pH 6.8 and temperature 25°C, SDZ (20 mg/L) was almost completely degraded within 60 min. XPS analysis showed that the NC not only protected and stabilized CoFe 2 O 4 , but also provided additional active sites for PMS activation. During SDZ degradation, SO 4 •- , HO • , • O 2 - and 1 O 2 were involved in the reaction, among which SO 4 • and HO • made the main contribution. Meanwhile, CoFe 2 O 4 @NC could be recovered by magnetic separation, and showed great stability (Co leaching 0.852 mg/L) and reusability. In the fifth cycle experiment, 85.02 % SDZ degradation was obtained. Based on the detected intermediates (12 intermediates were identified) and DFT calculations, possible degradation pathways for SDZ in CoFe 2 O 4 @NC/PMS were proposed. The condensed dual descriptor indicated that the N7, N11, and C15 atoms on SDZ molecule were the main sites of electrophilic attack, which was consistent with the detected intermediates. The degradation of SDZ involved hydroxylation of NH 2 , cleavage of S-N and extrusion of SO 2 . This study explored the improvements made in NC support material to catalytic performance and resistance to dissolution of spinel, providing new insights for subsequent researches., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Struvite recovery shows significant potential for simultaneously recovering nitrogen (N) and phosphorus (P) from swine wastewater but is challenged by the occurrence and transformation of antibiotic residuals. Electrochemically mediated struvite precipitation with sacrificial magnesium anode (EMSP-Mg) is promising due to its automation and chemical-free merits. However, the fate of antibiotics remains underexplored. We investigated the behavior of sulfadiazine (SD), an antibiotic frequently detected but less studied than others within the EMSP-Mg system. Significantly less SD (≤ 5%) was co-precipitated with recovered struvite in EMSP-Mg than conventional chemical struvite precipitation (CSP) processes (15.0 to 50.0%). The reduced SD accumulation in struvite recovered via EMSP was associated with increased pH and electric potential differences, which likely enhanced the electrostatic repulsion between SD and struvite. In contrast, the typical strategies used in enhancing P removal in the EMSP-Mg system, including increasing the Mg/P ratio or the Mg-release rates, have shown negligible effects on SD adsorption. Furthermore, typical coexisting ions (Ca 2+ , Cl - , and HCO 3 - ) inhibited SD adsorption onto recovered products. These results provide new insights into the interactions between antibiotics and struvite within the EMSP-Mg system, enhancing our understanding of antibiotic migration pathways and aiding the development of novel EMSP processes for cleaner struvite recovery., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

TiO 2 /expanded graphite (TiO 2 /EG) composite films were applied to water treatment for sulfadiazine (SDZ) degradation in a continuous flat plate photochemical reactor. The films were synthesized by sol-gel method and deposited on borosilicate glass by airbrush spray coating technique, forming a TiO 2 /C heterojunction. Increasing the amount of carbon promoted more efficient photocatalytic removal of SDZ under simulated sunlight, which increased from 9.1% in the absence of carbon to 49.8% for the material containing 7.5% C. From the formation of the TiO 2 /C heterojunction, morphological modifications, changes in the electronic structure and reduction of the band gap energy were observed. Type-II heterojunction formation was observed. Foreground and background irradiation modes were investigated, and a possible photocatalytic mechanism was proposed. TiO 2 /7.5 %-EG exhibited the best photocatalytic performance, with the possibility of reuse. The films showed good reusability in the SDZ degradation over 4 photocatalytic cycles. The influence of irradiation modes and the role of oxidizing species were discussed. The results showed that TiO 2 /EG hybrid films are a promising alternative for practical photocatalytic applications under sunlight., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Pharmaceuticals have been detected at high concentrations in landfill leachate and refuse, which may pose potential long-term environmental impacts. The interaction of pharmaceuticals between leachate and refuse contributes to their retention through in situ sorption, thereby mitigating this impact. However, limited efforts have been made to describe the distribution characteristics of pharmaceuticals in the refuse-leachate phase. In this study, two refuse and three leachate samples were used to obtain partitioning coefficients (K d ) for two typical pharmaceuticals, carbamazepine (CBZ) and sulfadiazine (SD), with campus soil as a comparison. Landfill refuse exhibited higher K d values (12.36 ± 0.90 and 19.76 ± 1.96 mL/g for CBZ and 1.90 ± 0.34 and 6.27 ± 0.58 mL/g for SD in two samples, respectively) than campus soil (3.73 ± 1.31 mL/g for CBZ and 0.81 ± 0.26 mL/g for SD), influenced by refuse properties such as higher organic matter (OM) content and specific surface area (SSA). The influence of leachate pH on K d values depended on the electrostatic interaction between the species of target pollutants and negatively charged refuse. The effect of humic acid (HA) was related to its binding with target pollutants in solution and its competition with them for sorption sites. Electrostatic repulsion, hydrogen bonding and π-π interaction were the proposed mechanisms in SD sorption on refuse, while hydrogen bonding participated in the sorption of CBZ. The results will help aid the understanding of the distribution of pharmaceuticals in the refuse-leachate system and improve corresponding management strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Waste-derived organics introduced to soils along with pharmaceutical active compounds (PhAC) are a crude mixture of compounds occurring in various size and polarity fractions. They affect the sorption of PhACs to soil; however, the relevant knowledge is still insufficient. The effects of different size and polarity fractions of manure-derived mobile organic matter (<63 µm) on the sorption of sulfadiazine, caffeine and atenolol to five topsoils were investigated. Mobilization of the PhACs was strongest in the presence of dissolved organic matter (mDOM, <0.45 µm), with a reduction of K d of sulfadiazine, caffeine and atenolol by mean factors of 0.66, 0.57 and 0.41, respectively. The mobilizing effects of colloidal organic matter (0.45-10 µm) were slightly smaller. Fine particulate organic matter (10-63 µm) reduced the sorption of the PhACs in slightly acidic soils (pH 6.0), but increased it in strongly acidic soil (pH 4.3). Furthermore, hydrophobic (HO-mDOM) and hydrophilic (HI-mDOM) fractions of mDOM reduced the sorption capacity but increased the sorption nonlinearity of PhACs in soils. Effects of HO-mDOM and HI-mDOM were PhAC specific. It is suggested to consider the varying impacts of mobile fractions in animal manure and/or treated wastewater in evaluating the fate and environmental relevance of associated PhACs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

A novel UV/oxalic acid functionalized corn straw biochar (OCBC)/peroxyacetic acid (PAA) system was built to degrade sulfadiazine from waters. 94.7 % of SDZ was removed within 30 min by UV/OCBC/PAA. The abundant surface functional groups and persistent free radicals (PFRs) on OCBC were responsible for these performances. Cyclic voltammetry (CV) and other characterization analysis revealed, under UV irradiation, the addition of OCBC served as electron donor, which might promote the reaction of electrons with PAA. The quenching and electron paramagnetic resonance (EPR) tests indicated that R-O•, 1 O 2 and •OH were generated. Theoretical calculations indicated sulfonamide bridge was vulnerable under the attacks of reactive species. In addition, high removal effect achieved by 5 reuse cycles and different real waters also suggested the sustainability of UV/OCBC/PAA. Overall, this study provided a feasible approach to remove SDZ with high mineralization efficiency, in addition to a potential strategy for resource utilization of corn straw., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, the absorption and fluorescence characteristics of sulfa drugs, specifically Sulfadiazine (SDZ), Sulfamerazine (SMZ), and Sulfamethazine (STZ), were examined across a pH range of 1-14. The absorption and fluorescence spectra of these sulfa drugs showed significant changes depending on the pH value. Analysis of their pH-dependent absorption and fluorescence properties indicated that these sulfa drugs could used to design molecular logic gates. The absorption and fluorescence behaviors at various wavelength maxima were utilized to design IMPLICATION and Improved-INHIBIT (I-INHIBIT) molecular logic gates., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In this study, the activation of peroxydisulfate (PS) by K 2 FeO 4 -activation biochar (KFeB) and acid-picking K 2 FeO 4 -activation biochar (AKFeB) was investigated to reveal the mechanism differences between iron site and graphitic structure in sulfadiazine (SDZ) degradation and ARB inactivation, respectively. KFeB/PS and AKFeB/PS systems had similar degradation property towards SDZ, but only KFeB/PS system showed excellent bactericidal property. The mechanism study demonstrated that dissolved SDZ was degraded through electron transfer pathway mediated by graphitic structure, while suspended ARB was inactivated through free radicals generated by iron-activated PS, accompanied by excellent removal on antibiotic resistance genes (ARGs). The significant decrease in conjugative transfer frequency indicated the reduced horizontal gene transfer risk of ARGs after treatment with KFeB/PS system. Transcriptome data suggested that membrane protein channel disruption and adenosine triphosphate synthesis inhibition were key reasons for conjugative transfer frequency reduction. Continuous flow reactor of KFeB/PS system can efficiently remove antibiotics and ARB, implying the potential application in practical wastewater purification. In conclusion, this study provides novel insights for classified and collaborative control of antibiotics and ARB by carbon-based catalysts driven persulfate advanced oxidation technology., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The development of a natural pyrite/peroxymonosulfate (PMS) system for the removal of antibiotic contamination from water represented an economic and green sustainable strategy. Yet, a noteworthy knowledge gap remained considering the underlying reaction mechanism of the system, particularly in relation to its pH sensitivity. Herein, this paper investigated the impacts of critical reaction parameters and initial pH levels on the degradation of sulfadiazine (SDZ, 3 mg/L) in the pyrite/PMS system, and elucidated the pH dependence of the reaction mechanism. Results showed that under optimal conditions, SDZ could be completely degraded within 5 min at a broad pH range of 3.0-9.0, with a pseudo-first-order reaction rate of >1.0 min -1 . The low or high PMS doses could lower degradation rates of SDZ through the decreased levels of active species, while the amount of pyrite was positively correlated with the removal rate of SDZ. The diminutive concentrations of anions exerted minor impacts on the decomposition of SDZ within the pyrite PMS system. Mechanistic results demonstrated that the augmentation of pH levels facilitated the transition from the non-radical to the radical pathway within the natural pyrite/PMS system, while concurrently amplifying the role of •OH in the degradation process of SDZ. This could be attributed to the change in interface electrostatic repulsion induced by pH fluctuations, as well as the mutual transformation between active species. The stable presence of the relative content of Fe(II) in the used pyrite was ensured owing to the reduced sulfur species acting as electron donors, providing the pyrite/PMS system excellent reusability. This paper sheds light on the mechanism regulation of efficient removal of organic pollutants through pyrite PMS systems, contributing to practical application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, magnetic coconut shell biochar loaded with spherical Fe 3 O 4 and γ-Fe 2 O 3 particles was successfully synthesized using a chemical coprecipitation method. The magnetic biochar exhibited a good magnetic separability and environmental security. The maximum sulfadiazine (SDZ) and norfloxacin (NOR) removal efficiencies were 94.8% and 92.3% at pH 4 and 25 °C with adsorbent dosage of 2.5 g/L, respectively. When antibiotic concentrations ranged from 5 to 50 mg/L, the theoretical maximum adsorption capacities of SDZ and NOR were 16.7 mg/g and 25.8 mg/g, respectively. The Langmuir isotherm and pseudo-second-order kinetic models could better describe the adsorption process of both antibiotics, implying the monolayer chemical adsorption. The thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. The ionic strength had no significant effect on the adsorption behavior of either antibiotic. Combined with BET, FTIR, and XPS results, the dominant mechanisms for SDZ and NOR adsorption were pore filling, π-π electron-donor-acceptor interaction, hydrogen bonds and surface complexation. Moreover, Lewis acid-base interaction also contributed to SDZ adsorption., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Sulfonamides can be effectively removed from wastewater through a photocatalytic process. However, the mineralization achieved by this method is a long-term and expensive process. The effect of shortening the photocatalytic process is the partial degradation and formation of intermediates. The purpose of this study was to evaluate the sensitivity and transformation of photocatalytic reaction intermediates in aerobic biological processes. Sulfadiazine and sulfamethoxazole solutions were used in the study, which were irradiated in the presence of a TiO 2 -P25 catalyst. The resulting solutions were then aerated after the addition of river water or activated sludge suspension from a commercial wastewater treatment plant. The reaction kinetics were determined and fifteen products of photocatalytic degradation of sulfonamides were identified. Most of these products were further transformed in the presence of activated sludge suspension or in water taken from the river. They may have been decomposed into other organic and inorganic compounds. The formation of biologically inactive acyl derivatives was observed in the biological process. However, compounds that are more toxic to aquatic organisms than the initial drugs can also be formed. After 28 days, the sulfamethoxazole concentration in the presence of activated sludge was reduced by 66 ± 7%. Sulfadiazine was practically non-biodegradable under the conditions used. The presented results confirm the advisability of using photocatalysis as a process preceding biodegradation.

Sulfadiazine (SDZ), a widely used effective antibiotic, is resistant to conventional biological treatment, which is concerning since untreated SDZ discharge can pose a significant environmental risk. Electro-Fenton (EF) technology is a promising advanced oxidation technology for efficiently removing SDZ. However, due to the limitations of traditional experimental methods, there is a lack of in-depth study on the mechanism of ·OH-dominated SDZ degradation in EF process. In this study, an EF system was established for SDZ degradation and the transformation products (TPs) were detected by mass spectrometry. Dynamic thermodynamic, kinetic and wave function analysis of reactants, transition states and intermediates were proposed by density functional theory calculations, which was applied to elucidate the underlying mechanism of SDZ degradation. Experimental results showed that amino, benzene, and pyrimidine sites in SDZ were oxidized by ·OH, producing TPs through hydrogen abstraction and addition reactions. ·OH was kinetically more likely to attack SDZ - than SDZ. Fe(IV) dominated the single-electron transfer oxidation reaction of SDZ, and the formed organic radicals can spontaneously generate the de-SO 2 product via Smiles rearrangement. Toxicity experiments showed the toxicity of SDZ and TPs can be greatly reduced. The results of this study promote the understanding of SDZ degradation mechanism in-depth. ENVIRONMENTAL IMPLICATION: Sulfadiazine (SDZ) is one of the antibiotics widely used around the world. However, it has posed a significant environmental risk due to its overuse and cannot be efficiently removed by traditional treatment methods. The lack of in-depth study on SDZ degradation mechanism under reactive species limits the improvement of SDZ degradation efficiency. Therefore, this work focused on SDZ degradation mechanism in-depth under electro-Fenton system through reactive species investigation, mass spectrometry analysis, and theoretical calculation. The results in this study can provide a theoretical basis for improving the SDZ degradation efficiency which will contribute to solving SDZ pollution problems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sulfadiazine (SDZ) as a typical sulfonamide antibiotic is commonly detected in wastewater, and its removal mechanism and transformation pathways in microalgae-mediated system remain unclear. In this study, the SDZ removal through hydrolysis, photodegradation, and biodegradation by Chlorella pyrenoidosa was investigated. Higher superoxide dismutase activity and biochemical components accumulation were obtained under SDZ stress. The SDZ removal efficiencies at different initial concentrations were 65.9-67.6%, and the removal rate followed pseudo first-order kinetic model. Batch tests and HPLC-MS/MS analyses suggested that biodegradation and photodegradation through the reactions of amine group oxidation, ring opening, hydroxylation, and the cleavage of S-N, C-N, C-S bond were dominant removal mechanisms and pathways. Characteristics of transformation products were evaluated to analyze their environmental impacts. High-value products of lipid, carbohydrate, and protein in microalgae biomass presented economic potential of microalgae-mediated metabolism for SDZ removal. The findings of this study broadened the knowledge for the microalgae self-protection from SDZ stress and provided a deep insight into SDZ removal mechanism and transformation pathways., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Combining piezoelectric effect and persulfate (PS) activation is a newly developed strategy for refractory emerging contaminants removal. In this work, borate SrBi 2 B 2 O 7 (SBBO) is firstly developed as a piezoelectric material to piezo-assisted activation of PS for the removal of sulfadiazine (SDZ) under ultrasonic irradiation (US). SDZ could be efficiently degraded by 85.61 % in the system of PS/SBBO/US with a pseudo-first-order rate constant of 0.0520 min -1 , which is faster than that in the systems of PS/SBBO (0.0210 min -1 ), SBBO/US (0.0041 min -1 ), PS/US (0.0074 min -1 ), and PS/BaTiO 3 /US (0.0120 min -1 ). The excellent degradation performance of the PS/SBBO/US system is mainly attributed to the piezoelectric effect of the SBBO which plays an important role in PS activation and accelerating reaction. Two oxidation processes, radical process (•O 2 - and •SO 4 - ) and non-radical process ( 1 O 2 and electron transfer), exist during the SDZ degradation. The system of PS/SBBO/US also attains excellent removal efficiency in different SDZ contained water bodies. The possible degradation pathways mainly include cleavage of bonds, ring-opening, and hydroxylation process, and the toxicity of intermediates was predicted by T.E.S.T. software. This study provides new insight into piezoelectric catalysis associated with PS activation for SDZ removal., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In this work, sulfide-modified zero-valent iron (S-Fe 0 ) was used to activate periodate (IO 4 - , PI) for sulfadiazine (SDZ) removal. 60 μM SDZ could be completely removed within only 1 min by S-Fe 0 /PI process. Compared with other oxidants including H 2 O 2 , peroxymonosulfate (PMS), peroxydisulfate (PDS), S-Fe 0 activated PI exhibited better performance for SDZ removal but with lower Fe leaching. Compared with Fe 0 /PI process, S-Fe 0 /PI process could reduce more than 80% Fe 0 and PI dosage. Inorganic ions and nature organic matters had negligible effect on SDZ removal in S-Fe 0 /PI system inducing its good SDZ removal efficiency in natural fresh water. 80.2% SDZ still could be removed within 2 min after 7th run. S-Fe 0 /PI process also exhibited 2.5 - 20.1 folds enhancement for various pollutants removal compared with Fe 0 /PI process. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical tests, and density functional theory (DFT) calculation were conducted to confirm the presence of sulfurs could enhance the reactivity of S-Fe 0 thus increased the efficiency of PI activation for antibiotics removal. Electron paramagnetic resonance spectroscopy (EPR) tests, radical quenching experiments, quantitative detection and DFT calculation were performed to illustrate the role of multiple reactive species in SDZ removal and the dominant pathway of multiple reactive species production. IO 3 · , · OH, O 2 -· , 1 O 2 , Fe IV , and SO 4 ·- all participated in SDZ removal. · OH played the major role in SDZ removal and the dominant routine of · OH production was IO 4 -  → O 2 -·  → H 2 O 2  →  · OH. Meanwhile, S-Fe 0 /PI process could efficiently mineralize SDZ and reduce the toxicity. Comparison with other PI activation approaches and SDZ treatment techniques further demonstrated S-Fe 0 was an efficient catalyst for PI activation and present study process was a promising approach for antibiotics removal., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A Fe-Cu bimetal catalyst (FCHS) was synthesized by depositing Fe 3 O 4 on the shell of CuO x hollow spheres, which were prepared via a soft template method. Several characterization methods, including XRD, SEM-EDS&mapping, TEM, FTIR, and XPS, were used to reveal the morphology and surface properties of FCHS. The characterization results demonstrated that the double-shell hollow structure is formed with a dense coating of Fe 3 O 4 nanoparticles on the surface of CuO x hollow spheres. FCHS can exhibit excellent catalytic activity to degrade sulfadiazine (SDZ) with the oxidant of persulfate (PS). The optimal SDZ removal performance was explored by adjusting reaction parameters, including catalyst dosage, oxidant dosage, and solution pH. The SDZ removal efficiency in the FCHS + PS system could reach 95% at the optimal reaction condition ([catalyst] 0  = 0.2 g/L, [PS] 0  = 2 mM, pH = 7.0) with 5 mg/L of SDZ. Meanwhile, the degradation efficiency decreased with the coexistence of phosphate or carbonate anions. According to the results of radicals scavenging experiments and the electron paramagnetic resonance analysis, the radicals of SO 4 · - , O 2 · - and ·OH generated in the FCHS + PS system contribute to the degradation of SDZ. Moreover, the results of XPS revealed that the solid-state charge-transfer redox couple of Fe(III)/Fe(II) and Cu(I)/Cu(II) can promote the activation of PS. It means that the cooperation effect between Cu oxides and Fe oxides in the double-shell structure is beneficial to the catalytic degradation of SDZ. Furthermore, four possible pathways for SDZ degradation were proposed according to the analysis of intermediate products detected by the LCMS-IT-TOF., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Sorption onto clays (montmorillonite and kaolinite), oxidation and sorption by manganese oxides (synthesized MnO and natural MnO), and coupled sorption-oxidation experiments were conducted for the removal of antibiotics sulfadiazine (SDZ) and ciprofloxacin (CIP) at pH 5 and 8. Individual sorption and oxidation modelling were carried out using the first-order kinetic model. A coupled sorption-oxidation kinetic model was developed to predict the simultaneous sorption and oxidation process. The coupled sorption-oxidation enhanced the antibiotic sorption, with the first-order sorption rate constants in the simultaneous presence of clays and manganese oxides (k sorp ) being higher than those with clays only (k sorp 0 ). In contrast, a depression was observed; the first-order oxidation and sorption combination rate constants in the simultaneous presence of manganese oxides and clays (k MnO ) were lower than those with manganese oxides only (k MnO 0 ). In the coupled sorption-oxidation reaction, 13.5-62.5% of SDZ and CIP removal was attributed to the sorption. The SDZ and CIP species distributions at pH 5 affected the coupled sorption and oxidation systems more than those at pH 8. The best removal efficiency was achieved by the montmorillonite-synthesized MnO combination, mainly due to the higher surface area (A BET ) and pore size of montmorillonite and synthesized MnO combination compared to other clays and manganese oxides combinations., Competing Interests: Declaration of competing interest The authors have no conflict of interest to declare., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

For the effective treatment of bacterial infection, it is essential to find a new strategy to deliver antibacterial agents. In the present study, the co-delivery of superfine nano-silver with solubilized sulfadiazine (SD) using cyclodextrin metal-organic frameworks (CD-MOF) as a carrier exhibited superior antibacterial efficacy to insoluble silver sulfadiazine. The abundant hydroxyl moieties in CD-MOF were utilized to reduce Ag precursor into silver nanoparticles (Ag NPs) of 4-5 nm and immobilized within the nano-sized cavities. Microporous CD-MOF facilitated the inclusion of SD molecules in the hydrophobic cavities of γ-cyclodextrin (γ-CD) molecular pairs. The hydrophilic CD-MOF can easily dissolve within exudates at the wound region to release the drug. This approach improved the aqueous solubility of SD by 50 folds which subsequently enhanced SD release and their antibacterial activity. The CD framework also prevented the aggregation of nano-silver particles, stabilizing the particle size and enhancing the curative effects. Hence, the incorporation of superfine nano-silver with solubilized SD using CD-MOF could be an alternate strategy to co-deliver silver and SD with higher efficacy., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the present work, laboratory column experiments were carried out to study the effect of pine bark amendment (at doses of 0, 12, 48 and 96 Mg ha -1 ) on the transport of three sulfonamide antibiotics (sulfadiazine -SDZ-, sulfamethazine -SMT-, and sulfachloropyridazine -SCP-) through two crop soils. All three sulfonamides showed high mobility in the unamend soils, with absence of retention in most cases. However, some differences were detected regarding the degree of interactions between sulfonamides and soils, being higher for soil 1, which was attributed to its higher organic carbon content. For both soils, interactions with the antibiotics studied followed the sequence SDZ < SMT < SCP, indicating an increase as a function of the hydrophobicity of sulfonamides. Pine bark amendment significantly increased the retention of the three sulfonamides in both soils. Specifically, in the case of soil 1, the incorporation of the highest dose of pine bark (96 Mg ha -1 ) caused that retention increased from 0% to 70.3% for SDZ, from 2.7% to 71.3% for SMT, and from 0% to 85.4% for SCP. This effect of pine bark is mainly attributed to its high organic carbon content (48.6%), including substances with potential to interact and retain antibiotics, as well as to its acidic pH (4.5). Therefore, pine bark amendment would be an effective alternative to reduce the transport of sulfonamides in soils and, thus, decrease risks of passing to other environmental compartments, as well as harmful effects on the environment and public health., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this work, ozone has been used to study the transformation of the antibiotic sulfadiazine (SDZ). SDZ and its transformation products was investigated using liquid chromatography coupled to mass spectrometry and using NMR. The results revealed that 6% of SDZ is transformed into 2-aminopyrimidine. A significant amount of SDZ undergoes a rearrangement reaction followed by ring-closing reactions. One of these products, SDZ-P15, is the main product after 240 min of ozonation. Almost 30% of SDZ transforms into SDZ-P15. SDZ was also transformed via the addition of one or more hydroxyl groups, via the oxidation of an amine group to a nitro group as well as via a bond cleavage reaction. Most of the intermediate products presented in this study have not previously been reported as SDZ transformation products formed using ozonation technology., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The structure of 2,4-(4'-aminobenzenamine)pyrimidine ( 1 ), a pyrimidine alkaloid previously isolated from the bulbs of Scilla madeirensis (Asparagaceae, synonym Autonoë madeirensis ), has been revised. These conclusions were met via comparison of reported NMR and EIMS data with those obtained from synthetic standards. The corrected structure is the antibiotic sulfadiazine ( 2 ), which has likely been isolated as a contaminant from the site of collection. The reported bioactivity of 1 as an α 1 -adrenoceptor antagonist should instead be ascribed to sulfadiazine. Our findings appear to show another example of an anthropogenic contaminant being identified as a natural product and emphasize the importance of considering the biosynthetic origins of isolated compounds within a phylogenetic context.

The synthesis of environmental-friendly metal-free photocatalysts has great significance in photocatalytic technology. In this work, we firstly report the successful synthesis of in situ epitaxial growth of g-C 3 N 4 on carbon dots through a facile thermal polymerization technique. Characterization and density functional theory (DFT) calculations were conducted to clarify the structure engineering and the electronic/chemical properties of the in-plane interconnected carbon dots/g-C 3 N 4 (C-CN) heterostructures. With the optimal carbon dots content, the C-CN exhibited 3.2 times higher degradation rate for sulfadiazine (SDZ) than that of g-C 3 N 4 . Besides, the C-CN heterostructures displayed excellent stability and reusability in five consecutive cycles. The enhanced photocatalytic activity was related to the narrowed band gap and the local electronic density of valance band and conduction band orbitals of the unique plane heterostructures, corroborated by the spectroscopic characterizations and theoretical calculations. Photogenerated holes dominated the degradation of SDZ, while OH showed a negligible contribution. Moreover, DFT calculation succeeded to predict that the atoms with high Fukin index (f 0 ) on SDZ molecule were more vulnerable to radicals attack. SDZ degradation pathway mainly included smiles-type rearrangement, SO 2 extrusion, ring hydroxylation and SN bond cleavage processes. The eco-toxicity assessment revealed the generation of less toxic intermediates after photocatalysis. Our findings not only afford a new technique for constructing g-C 3 N 4 -based in-plane heterostructures with high and stable photocatalytic efficiency, but also highlight the feasible application of metal-free photocatalysts in environmental remediation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objectives: To determine the physicochemical and microbiological stability of sulfadiazine suspensions (100 mg/mL) in simple syrup (A) and sorbitol (B) formulations prepared from commercially available tablets., Methods: An ultra-performance liquid chromatographic assay was developed and validated to determine the chemical stability of sulfadiazine. Three samples were prepared and stored at 5 and 25 °C and assayed at 0, 7, 14 and 30 days. Physical parameters (appearance, pH, particle size and viscosity) were also monitored. Microbiological examination was performed through the suitable counting method., Results: The formulations presented a sulfadiazine concentration of around 95% at the beginning at both temperatures. There was some variation in pH, viscosity and particle size distribution over time. The samples met the pharmacopoeia criteria of microbiological quality over 30 days, but only sulfadiazine formulated in syrup stored at 25 °C was suitable for use after one week., Conclusion: The sulfadiazine suspension in simple syrup was chosen as the most suitable formulation because it demonstrated stability for 14 days at room temperature, providing an alternative liquid dosage form of sulfadiazine for congenital toxoplasmosis treatment., (© 2019 John Wiley & Sons Ltd.)

Excessive sulfonamides accumulated in soil and groundwater seriously menace the ecological environment and human health. The performance of a Fenton-like system applying Fe 3+ and calcium peroxide (CaO 2 ) in the presence of l-cysteine(l-cys) for sulfadiazine (SDZ) degradation was investigated. Compared with other chelating agents such as citric acid, butyric acid and Ethylenediaminetetraacetic acid, l-cys could effectively promote the SDZ removal in Fe 3+ /CaO 2 system. With the addition of 0.5 mM l-cys, the SDZ degradation increased from 2.14% to 66.53% in 60 min. High concentration of HCO 3 - inhibited the degradation of SDZ while slightly negative effects on SDZ degradation were observed in the presence of Cl - or humic acid (HA) in l-cys/Fe 3+ /CaO 2 system. Electron paramagnetic resonance (EPR) analysis and radicals scavenge tests affirmed the generation of OH and O 2 - in l-cys/Fe 3+ /CaO 2 system. Possible degradation pathway of SDZ was speculated and the toxicity of SDZ intermediates was further evaluated. l-cys could enhance the reduction of Fe 3+ to Fe 2+ and reduced the Fe 3+ precipitation due to the l-cys could form stable complexes with Fe 3+ . l-cys/Fe 3+ /CaO 2 system exhibited high mineralization ability. Overall, these results indicated that l-cys is a promising chelating agent for sulfadiazine wastewater treatment., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Batch-type experiments were used to study adsorption-desorption of three sulfonamides: sulfadiazine (SDZ) sulfachloropyridazine (SCP), and sulfamethazine (SMT), in five crop soils, whereas laboratory soil column experiments were employed to obtain data on transport processes. Adsorption results were satisfactorily adjusted to Linear and Feundlich equations, with R 2 values above 0.95. Adsorption followed the sequence SDZ < SMT < SCP, showing higher values for soils with higher levels of organic carbon (OC) content. Conversely, desorption was higher in soils with less OC, and lower in soils with higher OC contents. The temporal moment analysis method gave values for the transport parameters τ and R which were significantly correlated with soil parameters related to organic matter, specifically OC and N concentrations. The higher retention of the three sulfonamides in soils with high organic matter content is a relevant fact, with value when programming management practices in agricultural soils, and specifically in relation to the spreading of animal manures, slurries, or waste containing these emerging pollutants., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Recent findings on the biological activity of thiazolidin-4-ones and taking into account the lack of effective drugs used in the treatment of toxoplasmosis, their numerous side effects, as well as the problem of drug resistance of parasites prompted us to look for new agents. We designed and synthesized a series of new thiazolidin-4-one derivatives through a two-step reaction between 4-substituted thiosemicarbazides with hydroxybenzaldehydes followed by the treatment with ethyl bromoacetate; maleic anhydride and dimethyl acetylenedicarboxylate afforded target compounds. The thiazolidin-4-one derivatives were used to assess the inhibition of Toxoplasma gondii growth in vitro. All active thiazolidine-4-one derivatives (12 compounds) inhibited T. gondii proliferation in vitro much better than used references drugs both sulfadiazine as well as the synergistic effect of sulfadiazine + trimethoprim (weight ratio 5:1). Most active among them derivatives 94 and 95 showed inhibition of proliferation at about 392-fold better than sulfadiazine and 18-fold better than sulfadiazine with trimethoprim. All active compounds ( 82 - 88 and 91 - 95 ) against T. gondii represent values from 1.75 to 15.86 (CC 30 /IC 50 ) lower than no cytotoxic value (CC 30 ).

This work present aims to evaluate the effect of a conventional wastewater treatment process on the number of nanoparticles, and the role of nanoparticles as a carrier of antibiotics. A set of methods based on asymmetrical flow field flow fractionation coupled with multi-angle light scattering to separate and quantify nanoparticles in real wastewater was established. The characterization of nanoparticles was conducted by transmission electron microscopy, energy dispersive spectrometer, UV-visible spectrophotometer and three-dimensional excitation-emission matrix fluorescence spectroscopy. The adsorption of different sizes of nanoparticles separated from the real wastewater for four targeted antibiotics (sulfadiazine, ofloxacin, tylosin and tetracycline) was studied. The results show that the number of nanoparticles were increased in the wastewater treatment process and the size range between 60 and 80 nm was predominant in wastewater samples. The nanoparticles were mainly composed of O, Si, Al and Ca elements and organic components were in the size range of 0-10 nm. Targeted antibiotics were dominantly adsorbed onto nanoparticles with 60-80 nm size range at each stage. The concentrations of tetracycline adsorbed on nanoparticles were surprisingly increased in the end of the treatment process, while ofloxacin and tylosin had the completely opposite phenomenon to tetracycline. The pH and ionic strength definitely affected the aggregation of nanoparticles and interaction with the antibiotics. It is of great significance to give insights into nanoparticle-antibiotic assemblages for the effective treatment and avoiding the water risks due to nanoparticles' ubiquitous and their risks of carrying antibiotics., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Conventionally the deep treatment and disinfection are fulfilled by different processes for municipal wastewater treatment, this work verified a breakthrough by one process of novel flow-through electro-Fenton (EF) with graphene-modified cathode, which is usually seemed to be ineffective. This process was firstly confirmed to be cost-effective for simultaneous sulfadiazines (SDZs) degradation and disinfection from municipal secondary effluent with a very low electrical energy consumption (EEC) of 0.21 kW h/m 3 , attributed to the high H 2 O 2 production of 4.41 mg/h/cm 2 on the novel graphite felt cathode modified by electrochemically exfoliated graphene (EEGr) with a low EEC of 3.08 kW h/(kg H 2 O 2 ). Compared with the ineffective SDZs degradation by the conventional flow EF, this process was more cost-effective and overcame the harsh requirements on electrolyte concentration. It also showed good effectiveness in the degradation of different antibiotics, and the graphene-modified cathode still kept stable performance after eight consecutive runs. Account for the combined action of OH and active chlorine, the formation of hydroxylated and chlorine containing by-products was confirmed, and a possible degradation mechanism for SDZs was proposed. This flow-through EF process provided an alternative method for the disinfection and antibiotics degradation by one process for the treatment and reuse of municipal secondary effluent., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The novel hexagonal boron nitride (BN) bundles, assembled by a plenty of BN fibers with high adsorption capacity and outstanding recyclability, were prepared easily as an efficient adsorbent for antibiotics. It is an excellent substitute for carbonaceous adsorbent to overcome the shortcoming in low adsorption capacity and poor recyclability. Its high surface area can reach up to 871.456 m 2  g -1 . The adsorption capacity and removal percentage to sulfadiazine (SDZ, 0.328 mmol g -1 , 82.192%), oxytetracycline (OTC, 0.202 mmol g -1 , 92.890%) and erythromycin (EM, 0.126 mmol g -1 , 90.140%) are superior compared with activated carbon and graphene nanoplatelets. It is interesting that BN bundles have a better adsorption to small molecules since huge molecules are easily restricted to enter the micropores, which was defined as micropore-filling effect. Moreover, the adsorption isotherms are well fitted by the Langmuir and Tempkin model, while pseudo-second-order model can better describe the adsorption kinetics. The adsorption mechanisms were deduced to be mainly π-π electron-donor-accepter interaction while electrostatic force and hydrophobic interaction played a significant role. The excellent reusability can be seen from the high removal efficiency after five recycles suggesting the BN bundles was a promising adsorbent for the efficient removal of antibiotics pollutants., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Comprehension of the nanomechanical response of crystalline materials requires the understanding of the elastic and plastic deformation mechanisms in terms of the underlying crystal structures. Nanoindentation data were combined with structural and computational inputs to derive a molecular-level understanding of the nanomechanical response in eight prototypical sulfa drug molecular crystals. The magnitude of the modulus, E, was strongly connected to the non-covalent bond features, that is, the bond strength, the relative orientation with the measured crystal facet and their disposition in the crystal lattice. Additional features derived from the current study are the following. Firstly, robust synthons well isolated by weak and dispersive interactions reduce the material stiffness; in contrast, the interweaving of interactions with diverse energetics fortifies the crystal packing. Secondly, mere observation of layered structures with orthogonal distribution of strong and weak interactions is a prerequisite, but inadequate, to attain higher plasticity. Thirdly, interlocked molecular arrangements prevent long-range sliding of molecular planes and, hence, lead to enhanced E values. In a broader perspective, the observations are remarkable in deriving a molecular basis of the mechanical properties of crystalline solids, which can be exploited through crystal engineering for the purposeful design of materials with specific properties., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Xenobiotic compounds are commonly detected in inland waters. Sunlight-induced photochemical reactions contribute to xenobiotic degradation, but the role of different photoreactions on large geographic scales remains poorly understood. Here, we used a combination of photochemical modelling and large-scale field data from 1020 lakes across Sweden to elucidate the photodegradation kinetics of the commonly used antibiotic sulfadiazine (SDZ) in organic matter-rich lakes. SDZ occurs in two forms, namely acidic HSDZ (pK a  = 6.5) and basic/deprotonated SDZ - . Both species are oxidised fast by the photogenerated triplet states of natural organic matter ( 3 NOM*). However, they also undergo efficient back reactions because the partially oxidised HSDZ (and SDZ - to a larger extent) can be reduced back to the initial compounds by the phenolic moieties contained in NOM. Typical lakes in Sweden are rich in NOM and have low pH, with the consequence that SDZ photochemistry would be dominated by HSDZ. Our simulation results showed that SDZ photodegradation kinetics in Swedish lakes would become significantly slower with increasing water depth and pH, while it depended little on latitude, which affects irradiance, or on organic matter content. As a consequence, SDZ would be particularly persistent in lakewater in some densely populated areas with relatively deep and high-pH lakes such as, most notably, the Stockholm region. Here the surface waters could be more heavily contaminated by pharmaceuticals compared to the scarcely populated regions in the centre-north of the country, where lakewater could otherwise promote an efficient photodegradation of SDZ., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Antibiotics discharged to the environment constitute a main concern for which different treatment alternatives are being studied, some of them based on antibiotics removal or inactivation using by-products with adsorbent capacity, or which can act as catalyst for photo-degradation. But a preliminary step is to determine the general characteristics and magnitude of the degradation process effectively acting on antibiotics. A specific case is that of sulfonamides (SAs), one of the antibiotic groups most widely used in veterinary medicine, and which are considered the most mobile antibiotics, causing that they are frequently detected in both surface- and ground-waters, facilitating their entry in the food chain and causing public health hazards. In this work we investigated abiotic and biotic degradation of three sulfonamides (sulfadiazine -SDZ-, sulfachloropyridazine -SCP-, and sulfamethazine -SMT-) in aqueous media. The results indicated that, in filtered milliQ water and under simulated sunlight, the degradation sequence was: SCP > SDZ ≈ SMT. Furthermore, the rate of degradation clearly increased with the raise of pH: at pH 4.0, half-lives were 1.2, 70.5 and 84.4 h for SCP, SDZ and SMT, respectively, while at pH 7.2 they were 2.3, 9.4 and 13.2 h for SCP, SMT and SDZ. The addition of a culture medium hardly caused any change in degradation rates as compared to experiments performed in milliQ water at the same pH value (7.2), suggesting that in this case sulfonamides degradation rate was not affected by the presence of some chemical elements and compounds, such as sodium, chloride and phosphate. However, the addition of bacterial suspensions extracted from a soil and from poultry manure increased the rate of degradation of these antibiotics. This increase in degradation cannot be attributed to biodegradation, since there was no degradation in the dark during the time of the experiment (72 h). This indicates that photo-degradation constitutes the main removal mechanism for SAs in aqueous media, a mechanism that in this case was favored by humic acids supplied with the extracts from soil and manure. The overall results could contribute to the understanding of the environmental fate of the three sulfonamides studied, aiding to program actions that could favor their inactivation, which is especially relevant since its dissemination can involve serious environmental and public health risks., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The solvate formation of sulfadiazine (SDZ) was systematically studied in the 4 selected solvents with the aids of experiment and simulation methods. The intermolecular interactions between solute and solvent molecules in different solid states were analyzed and compared through their single crystal structures, and the solution behavior of SDZ was discussed using molecular dynamics simulations. The results indicated that SDZ was easy to form solvates with the solvents having strong hydrogen bond acceptor ability, which determined the formation of hydrogen bonding synthon. Furthermore, the SDZ molecules conformation and packing were compared in various crystal structures. In addition, the desolvation processes of SDZ solvates were studied to investigate the role of solvent in different solvate structures., (Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

A new trend describes the development and validation of a simple, sensitive and selective kinetic spectrophotometric methods for the determination of sulfadiazine in pharmaceutical formulations has been conducted. In this paper, sulfadiazine was derivatized as a new organic compound 4(4-sulphophenylazo) pyrogallol, 4-SPAP, by coupling pyrogallol with diazotized sulfadiazine in medium of controlled pH. 4-SPAP was characterized by techniques of FT-IR, H-NMR, GC-Mass, TG and DSC thermal analysis methods. Solvatochromic behavior in solvents of various polarities was also investigated. The determination of sulfadiazine was accomplished by initial rate and fixed time methods. These methods were based on the reaction of the compound containing sulfadiazine, 4-SPAP, with Ca(II) to form colored product with a maximum absorbance at 520 nm. The two methods were adopted for constructing the calibration curves and examined for their suitability for the quantitation of sulfadiazine in pharmaceuticals. The limit of detection (LOD) and limit of quantification (LOQ) were found to be, by initial rate method, 0.35 and 1.05 μg·mL -1 and that by fixed time method were found to be 0.69 and 2.07 μg·mL -1 , respectively. The percent relative standard deviations (%RSD) for the results ranged from 1.04% to 1.76% and 0.85% to 1.42% for the initial rate and fixed time methods of the proposed kinetic spectrophotometric method, respectively. The existence of common excipients in the pharmaceutical formulation did not produce any significant interference. Statistical comparison was reported as indicated from the F- and t-test data of the proposed methods with that of reference method showing excellent agreement and indicating no significant difference in their accuracy and precision., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To seek the new medicinal potential of sulfadiazine drug, the free amino group of sulfadiazine was exploited to obtain acyl/aryl thioureas using simple and straightforward protocol. Acyl/aryl thioureas are well recognized bioactive pharmacophore containing moieties. A new series (4a-4j) of sulfadiazine derived acyl/aryl thioureas was synthesized and characterized through spectroscopic and elemental analysis. The synthesized derivatives 4a-4j were subjected to calf intestinal alkaline phosphatase (CIAP) activity. The derivative 4a-4j showed better inhibition potential compared to standard monopotassium phosphate (MKP). The compound 4c exhibited higher potential in the series with IC 50 0.251 ± 0.012 µM (standard KH 2 PO 4 4.317 ± 0.201 µM). Lineweaver-Burk plots revealed that most potent derivative 4c inhibition CIAP via mixed type pathway. Pharmacological investigations showed that synthesized compounds 4a-4j obey Lipinsk's rule. ADMET parameters evaluation predicted that these molecule show significant lead like properties with minimum possible toxicity and can serve as templates in drug designing. The synthetic compounds show none mutagenic and irritant behavior. Molecular docking analysis showed that compound 4c interacts with Asp273, His317 and Arg166 amino acid residues., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Antibiotics degradation remains a longstanding challenge in wastewater treatment. Towards this objective, we have developed a novel technique combining cavitating jets impingement with multiple synergetic methods, i.e., UV/Fenton, analogous Fenton, and photocatalytic oxidation in the present work. Three kinds of antibiotics namely amoxicillin, doxycycline and sulfadiazine sodium, are selected as model pollutants. Individual application of cavitating jets impingement is firstly conducted to evaluate the effects of jets impinging forms and nozzle inlet pressure. The effects of impingement on promoting antibiotics degradation and weakening the coalescing effects of cavitation bubbles are confirmed. Perpendicular double cavitating jets impingement is proved to be the most effective impinging form and brought a COD (chemical oxidation demand) reduction of 30.04% with the impinging effect index 1.22 at jet inlet pressure 10 MPa. Increasing the jet inlet pressure can improve the COD reduction and the effectiveness of impingement. Subsequently, UV/Fenton process is introduced to intensify the degradation process. The effects of important parameters are investigated by means of orthogonal experiments and the maximum COD reduction is up to 71.16% under the optimum conditions. Then, analogous Fenton process and photocatalytic oxidation are adopted for further enhancing the COD reduction. Different approaches used in the present work are assessed in view of multiple aspects. With COD reduction of 79.92%, the combination of cavitating jets impingement, UV/Fenton, analogous Fenton and photocatalytic oxidation is proved to be optimum method for antibiotic wastewater treatment., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Microplastics and antibiotics are two classes of emerging contaminants with proposed negative impacts to aqueous ecosystems. Adsorption of antibiotics on microplastics may result in their long-range transport and may cause compound combination effects. In this study, we investigated the adsorption of 5 antibiotics [sulfadiazine (SDZ), amoxicillin (AMX), tetracycline (TC), ciprofloxacin (CIP), and trimethoprim (TMP)] on 5 types of microplastics [polyethylene (PE), polystyrene (PS), polypropylene (PP), polyamide (PA), and polyvinyl chloride (PVC)] in the freshwater and seawater systems. Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD) analysis revealed that microplastics have different surface characterizes and various degrees of crystalline. Adsorption isotherms demonstrated that PA had the strongest adsorption capacity for antibiotics with distribution coefficient (K d ) values ranged from 7.36 ± 0.257 to 756 ± 48.0 L kg -1 in the freshwater system, which can be attributed to its porous structure and hydrogen bonding. Relatively low adsorption capacity was observed on other four microplastics. The adsorption amounts of 5 antibiotics on PS, PE, PP, and PVC decreased in the order of CIP > AMX > TMP > SDZ > TC with K f correlated positively with octanol-water partition coefficients (Log K ow ). Comparing to freshwater system, adsorption capacity in seawater decreased significantly and no adsorption was observed for CIP and AMX. Our results indicated that commonly observed polyamide particles can serve as a carrier of antibiotics in the aquatic environment., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The potential of horseradish peroxidase (HRP) to catalyze the removal of sulfonamides from water and the effects of different H 2 O 2 and HRP concentrations were investigated. Six sulfonamides, each with a five- or six-membered heterocyclic group, including sulfamethoxazole (SMX), sulfathiazole (STZ), sulfapyridine (SPD), sulfadiazine (SDZ), sulfamerazine (SMR) and sulfamethoxypyridazine (SMP) were selected as target compounds. All sulfonamides exhibit a pseudo-first-order dependence of the concentration versus the reaction time. The decay rate (k, h -1 ) of the six sulfonamides spiked individually exhibit a trend following the order of STZ > SMP, SPD > SMR > SDZ » SMX. When spiked together, the coexistent sulfonamides might act as mediators for the enhancement of SMX removal and as competitors for the decreased removal of most sulfonamides. Moreover, six transformation products of SDZ are identified by the Thermo Scientific LTQ Orbitrap Elite technique. SDZ transformation involves two steps: one is the Smiles re-arrangement of the structure, and the other is oxidation and sulfur dioxide extrusion. This study is the first to report the removal dynamics of sulfonamides in HRP-catalyzed reactions and the identified products of SDZ., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We propose an in vitro permeability assay by using a modified lipid membrane to predict the in vivo intestinal passive permeability of drugs. Two conditions were tested, one with a gradient pH (pH 5.5 donor/pH 7.4 receptor) and the other with an iso-pH 7.4. The predictability of the method was established by correlating the obtained apparent intestinal permeability coefficients (P app ) and the oral dose fraction absorbed in humans (f a ) of 16 drugs with different absorption properties. The P app values correlated well with the absorption rates under the two conditions, and the method showed high predictability and good reproducibility. On the other hand, with this method, we successfully predicted the transport characteristics of oral sulfadiazine (SDZ). Also, the tradeoff between the increase in the solubility of SDZ by its complex formation with cyclodextrins and/or aminoacids and its oral permeability was assessed. Results suggest that SDZ is transported through the gastrointestinal epithelium by passive diffusion in a pH-dependent manner. These results support the classification of SDZ as a high/low borderline permeability compound and are in agreement with the Biopharmaceutics Classification Systems (BCS). This conclusion is consistent with the in vivo pharmacokinetic properties of SDZ.

Sulfonamides, one of the commonest antibiotics, were widely used on humans and livestock to control pathema and bacterial infections resulting in further environmental risks. The present study evaluated the adsorption and degradation of sulfadiazine (SDZ) and sulfamethoxazole (SMX) in an agricultural soil system under an anaerobic condition. Low sorption coefficients (K d , 1.22 L kg -1 for SDZ and 1.23 L kg -1 for SMX) obtained from Freundlich isotherms experiment indicated that poor sorption of both antibiotics may pose a high risk to environment due to their high mobility and possibility of entering surface and ground water. Degradation occurred at a lower rate under the anaerobic environment, where both two antibiotics had higher persistence in sterile and non-sterile soils with degradation ratio <75% and DT50 > 20 d. Additionally, the addition of manure slightly increased degradation rates of SDZ and SMX, but there were no significant differences between single and repeated manure application at a later stage (p > 0.05), which suggested that the degradation was affected by both biotic and abiotic factors. Degradation rates would be slower at a higher concentration, indicating that degradation kinetics of SDZ and SMX were dependent on initial concentrations. During the degradation period, the antibiotics removal may change temperature, pH, sulfate and nitrate in soil, which suggested that the variation of antibiotics concentrations was related to the changes of soil physicochemical properties. An equation was proposed to elucidate the link between adsorption and degradation under different conditions, and to predict potential environmental risks of antibiotics., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Previous studies have shown that the photodegradation of some pollutants, induced by the excited triplet states of chromophoric dissolved organic matter ( 3 CDOM*), can be inhibited by back-reduction processes carried out by phenolic antioxidants occurring in dissolved organic matter (DOM). Here, for the first time to our knowledge, we included such an inhibition effect into a photochemical model and applied the model predictions to sulfadiazine (SDZ), a sulfonamide antibiotic that occurs in surface waters in two forms, neutral HSDZ and anionic SDZ - (pK a  = 6.5). The input parameters of the photochemical model were obtained by means of dedicated experiments, which showed that the inhibition effect was more marked for SDZ - than for HSDZ. Compared to the behavior of 2,4,6-trimethylphenol, which does not undergo antioxidant inhibition when irradiated in natural water samples, the back-reduction effect on the degradation of SDZ was proportional to the electron-donating capacity of the DOM. According to the model results, direct photolysis and OH reaction would account for the majority of both HSDZ and SDZ - photodegradation in waters having low dissolved organic carbon (DOC < 1 mgC L -1 ). With higher DOC values (>3-4 mgC L -1 ) and despite the back-reduction processes, the 3 CDOM* reactions are expected to account for the majority of HSDZ phototransformation. In the case of SDZ - at high DOC, most of the photodegradation would be accounted for by direct photolysis. The relative importance of the triplet-sensitized phototransformation of both SDZ - and (most importantly) HSDZ is expected to increase with increasing DOC, even in the presence of back reduction. An increase in water pH, favoring the occurrence of SDZ - with respect to HSDZ, would enhance direct photolysis at the expense of triplet sensitization. SDZ should be fairly photolabile under summertime sunlight, with predicted half-lives ranging from a few days to a couple of months depending on water conditions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A novel, efficient, easy to use, environmentally friendly and cost-effective methodology is developed for the indirect spectrophotometric determination of sulfadiazine in different samples. The method is based on the micelle-mediated extraction of silver sulfadiazine and converting the silver content of the resultant surfactant-rich phase to the silver nanoparticles via generation of [Ag(NH 3 ) 2 ] + followed by its chemical reduction using ascorbic acid. The changes in the amplitude of localized surface plasmon resonance peak of silver nanoparticles as a function of sulfadiazine concentration in the sample solution was monitored using fiber optic linear array spectrophotometry at 457nm. The experimental conditions were thoroughly investigated and optimized. Under the optimized condition, the developed procedure showed dynamic linear calibration within the range of 10.0-800.0μgL -1 with a detection limit of 2.8μgL -1 for sulfadiazine. The relative standard deviation of the method for six replicate measurements at 150.0μgL -1 of sulfadiazine was 4.7%. The developed method was successfully applied to the determination of sulfadiazine in different samples including well water, human urine, milk and pharmaceutical formulation., (Copyright © 2017. Published by Elsevier B.V.)

The adsorption of sulfadiazine from water by expanded graphite (EG), a low cost and environmental-friendly adsorbent, was investigated. Several adsorption parameters (including the initial sulfadiazine concentration, contact time, pH of solution, ionic strength and temperature) were studied. Results of equilibrium experiments indicated that adsorption of sulfadiazine onto EG were better described by the Langmuir and Tempkin models than by the Freundlich model. The maximum adsorption capacity is calculated to be 16.586 mg/g at 298 K. The kinetic data were analyzed by pseudo-first-order, pseudo-second-order and intraparticle models. The results indicated that the adsorption process followed pseudo-second-order kinetics and may be controlled by two steps. Moreover, the pH significantly influenced the adsorption process, with the relatively high adsorption capacity at pH 2-10. The electrostatic and hydrophobic interactions are manifested to be two main mechanisms for sulfadiazine adsorption of EG. Meanwhile, the ionic concentration of Cl - slightly impacted the removal of sulfadiazine. Results of thermodynamics analysis showed spontaneous and exothermic nature of sulfadiazine adsorption on EG. In addition, regeneration experiments imply that the saturated EG could be reused for sulfadiazine removal by immersing sodium hydroxide.

Bacterial infection is one of the vital reasons of morbidity and mortality, especially in developing countries. It appears silently without bothering the geological borders and imposes a grave threat to humanity. Nuclear medicine technique has an important role in helping early diagnosis of deep-seated infections. The aim of this study was to develop a new radiopharmaceutical 99m Tc-labeling sulfadiazine as an infection imaging agent. Radiolabeling of sulfadiazine with technetium-99m ( 99m Tc) was carried out using stannous tartrate as a reducing agent in the presence of gentistic acid at pH = 5. The quality control tests revealed ~98% labeling efficiency. Paper chromatographic (PC) and instant thin-layer chromatographic (ITLC) techniques were used to analyze radiochemical yield. Biodistribution and infection specificity of the radiotracer were performed with Escherichia coli (E. coli) infection-induced rats. Scintigraphy and glomerular filtration rate (GFR) study was performed in E. coli-infected rabbits. Scintigraphy indicated E. coli infection targeting potential of 99m Tc-SDZ, while biodistribution study showed minimal uptake of 99m Tc-SDZ in non-targeted tissues. The uptake in the kidneys was found 2.56 ± 0.06, 2.09 ± 0.10, and 1.68 ± 0.09% at 30 min, 1 h, and 4 h, respectively. The infected muscle (target) to non-infected muscle (non-target) ratio (T/NT) was found 4.49 ± 0.04, 6.78 ± 0.07, and 5.59 ± 0.08 at 30 min, 1 h, and 4 h, respectively.

Trimethoprim is a diaminopyrimidine antibacterial agent that, like sulfonamides, inhibits bacterial folic acid synthesis, but at a different stage in the metabolic pathway. It has a similar spectrum of activity to the sulfonamides and is given by mouth or by injection, either alone or in conjunction with a sulfonamide, such as sulfadiazine. Sulfadiazine is a bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. The combination of the two drugs produces a synergistic effect against both Gram-positive and Gram-negative aerobic bacteria, by inhibiting enzymes in the folic acid pathways, which in turn inhibits bacterial thymidine synthesis. There are no published studies of the stability of the combination of trimethoprim and sulfadiazine in a liquid dosage form. An extemporaneously compounded suspension from pure drug powders or commercial tablets would provide an alternative option to meet unique patient needs. The purpose of this study was to determine the physicochemical stability of trimethoprim combined with sulfadiazine in PCCA base SuspendIt. PCCA base SuspendIt is a sugar-free, paraben-free, dye-free, and gluten-free thixotropic vehicle containing a natural sweetener obtained from the monk fruit. It thickens upon standing to minimize settling of any insoluble drug particles and becomes fluid upon shaking to allow convenient pouring during administration to the patient. A robust stability-indicating high-performance liquid chromatographic assay for the simultaneous determination of trimethoprim and sulfadiazine in SuspendIt was developed and validated. This assay was used to determine the chemical stability of both drugs in SuspendIt. Samples were prepared and stored under three different temperature conditions (5°C, 25°C, 40°C), and assayed using the high-performance liquid chromatographic assay at pre-determined intervals over an extended period of time as follows: 0, 7, 14, 30, 45, 60, 91, 120, and 182 days at each designated temperature. Physical data such as pH, viscosity, appearance, and average particle size were also monitored. The study showed that drug concentration did not go below 90% of the label claim (initial drug concentration) at room temperature and in the refrigerator. The pH values also did not change significantly. There was some variability in viscosity and average particle size. This study demonstrates that trimethoprim and sulfadiazine are physically and chemically stable in combination in SuspendIt for 182 days at room temperature and in the refrigerator, thus providing a viable, compounded alternative for both drugs in a liquid dosage form, with an extended beyond-use-date to meet patient needs., (Copyright© by International Journal of Pharmaceutical Compounding, Inc.)

Sulfonamide derivatives serve as an important building blocks in the drug design discovery and development (4D) process. Ciprofloxacin-, sulfadiazine- and amantadine-based sulfonamides were synthesized as potent inhibitors of jack bean urease and free radical scavengers. Molecular diversity was explored and electronic factors were also examined. All 24 synthesized compounds exhibited excellent potential against urease enzyme. Compound 3e (IC 50 = 0.081 ± 0.003 µM), 6a (IC 50 = 0.0022 ± 0.0002 µM), 9e (IC 50 = 0.0250 ± 0.0007 µM) and 12d (IC 50 = 0.0266 ± 0.0021 µM) were found to be the lead compounds compared to standard (thiourea, IC 50 = 17.814 ± 0.096 µM). Molecular docking studies were performed to delineate the binding affinity of the molecules and a kinetic mechanism of enzyme inhibition was propounded. Compounds 3e , 6a and 12d exhibited a mixed type of inhibition, while derivative 9e revealed a non-competitive mode of inhibition. Compounds 12a , 12b , 12d , 12e and 12f showed excellent radical scavenging potency in comparison to the reference drug vitamin C., Competing Interests: The authors declare no conflict of interest.

Batch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14 C-labeled contaminants, the hydrophobic chlordecone (CLD) and the sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). The transport behaviors of CLD, SDZ, and MWCNTs were studied at environmentally relevant concentrations (0.1-10 mg L -1 ) and they were applied in the column studies at different times. The breakthrough curves and retention profiles were simulated using a numerical model that accounted for the advective-dispersive transport of all compounds, attachment/detachment of MWCNTs, equilibrium and kinetic sorption of contaminants, and co-transport of contaminants with MWCNTs. The experimental results indicated that the presence of mobile MWCNTs facilitated remobilization of previously deposited CLD and its co-transport into deeper soil layers, while retained MWCNTs enhanced SDZ deposition in the topsoil layers due to the increased adsorption capacity of the soil. The modeling results then demonstrated that the mobility of engineered nanoparticles (ENPs) in the environment and the high affinity and entrapment of contaminants to ENPs were the main reasons for ENP-facilitated contaminant transport. On the other hand, immobile MWCNTs had a less significant impact on the contaminant transport, even though they were still able to enhance the adsorption capacity of the soil., (Copyright © 2016 Elsevier Ltd. All rights reserved.)