Sulfamethoxazole Concentration Research Articles

Simultaneous electrochemical removal of three microcystin congeners and sulfamethoxazole in natural water

Microcystins (MCs), frequently detected in freshwater ecosystems, have raised significant human health and ecological concerns. New approaches are being developed to control and remove MCs. In this study, we examined factors influencing the efficacy of electrochemical oxidation as a means of control. Anode material (Pt/Ti, Ta2O5-IrO2/Ti, SnO2-SbO2/Ti, boron-doped diamond (BDD)/Si), anode surface area ratios and solution volumes, initial pollutant concentrations, and the co-existing antibiotic sulfamethoxazole (SMX) were investigated. MCs and SMX were dissolved in filtered Taihu Lake water to simulate the natural aquatic environment. The results showed that non-active anodes, lower initial concentration of MC, larger surface area ratio of anode to cathode, and smaller ratio of reaction solution volume to anode surface area could promote the degradation target pollutants. Under optimal conditions in this study, the degradation rates of MC-LR, MC-YR, MC-RR, and SMX each reached more than 90% within 6 hours, and the removal efficiency of MC-YR was the highest among three congeners. The effect of SMX on the degradation of MC congeners depended mainly on their concentration differences, such that when the initial concentration of SMX was one to two orders of magnitude lower than microcystin, the presence of SMX would promote the degradation of MCs. In contrast, when the initial concentration of SMX was higher than that of microcystin by approximately an order of magnitude, sulfamethoxazole would inhibit the degradation of MCs by between 4.6% and 24.5%. Ultra-high-performance liquid chromatography tandem mass spectrometry analysis revealed that the three MC congeners were electrochemically degraded through aromatic ring oxidation, alkene oxidation, and bond cleavage on the ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) side chain. Notably, the removal of MCs was accompanied by a decline in the hardness of the reaction water. This study provided insights into electrochemical degradation of microcystins and antibiotics in natural water, offering suggestions for its practical application.

Effects of nanoparticles on the anaerobic digestion properties of sulfamethoxazole-containing chicken manure and analysis of bio-enzymes

Abstract Medium-temperature anaerobic digestion experiments lasting for 55 days were conducted using sulfamethoxazole (SMX)-containing chicken manure in sequential batch reactors added with nano-Fe2O3 at a concentration of 300 mg·kg−1·TS or nano-C60 at a concentration of 100 mg·kg−1·TS. The effects of nanoparticles on the anaerobic digestion properties of SMX-containing chicken manure were assessed by measuring the following indicators: biogas production by anaerobic digestion, chemical parameters, enzyme concentrations, and bacterial diversity and changes in antibiotic concentrations over time. The law of bacterial degradation of SMX was analyzed. The results showed that (1) adding either nano-Fe2O3 or nano-C60 promoted biogas production by anaerobic production from chicken manure containing different concentrations of SMX, and the cumulative biogas production in Fe2O3 and nano-C60 increased by 35.4% and 130.7%, respectively. The final cumulative biogas productions in different groups were as follows: 3,712(CK), 4,281(S1), 3,968(S2), 4,061(S3), 4,498(S4), and 4,639(S5) mL and the final concentration of SMX residues varied between 99.79% and 99.94%; (2) Bacterial abundance at the phylum level: on day 1, Firmicutes and Bacteroidota were the main dominant bacterial phyla, with relative abundances of 45.13–68.53% and 26.12–48.32%, respectively. The addition of nanoparticles increased the abundance of Bacteroidota in S4 and S5 significantly. The abundance of Bacteroidota was slightly higher in the group added with nanoparticles than in S2. On day 50, Firmicutes became the dominant bacterial phylum, and its relative abundance varied little across the groups, ranging from 90.87% to 94.54%; (3) At different stages, the bacterial community structure at the genus level was dramatically affected by substrates. As nutrients were being depleted, some bacterial communities lost their original competitive advantages. On day 5, the relative abundance of Prevotella increased. Especially, the relative abundances of Prevotella in S4 and S5 added with nanoparticles were lower than that in S2 by 8–10%. On day 15, the relative abundance of Prevotella in S2 decreased compared with the control group CK. A decrease was also observed in S4 and S5, although to a smaller extent than in S2.

Sulfamethoxazole removal and ammonium conversion in microalgae consortium: Physiological responses and microbial community changes

Microalgae (Mychonastes sp.) consortium was investigated for nutrient and antibiotics removal and its responses to varying sulfamethoxazole (SMX) concentrations (0–1000 μg/L) in ammonia-rich wastewater. The results showed that the introduction of SMX (100–1000 μg/L) slightly improved ammonium nitrogen removal efficiency instead of inhibition. Swift SMX degradation was observed across all SMX-treated systems, with the highest SMX removal efficiency (96 %) at an SMX concentration of 100 μg/L. Biodegradation remained the dominant SMX removal mechanism, contributing 78 % of SMX removal at an SMX concentration of 800 μg/L, while adsorption and photolysis played minor roles. Addition of SMX augmented biomass and lipid productivity, but decreased chlorophyll contents in the microalgae consortium. Furthermore, extracellular polymeric substance (EPS) production correlated positively with SMX input concentration, with the microalgae consortium exposed to 800 μg/L SMX displaying the most pronounced stimulation of protein production (51.5 ± 2.0 mg/g DCW) and polysaccharides production (74.8 ± 3.9 mg/g DCW). In response to an increase in SMX concentrations, enzyme activities associated with antioxidant defense, such as superoxide dismutase (SOD), peroxidase (POD) and malondialdehyde (MDA) increased, the catalase (CAT) decreased, indicating an initial defense mechanism. Concurrently, the relative abundance of Mychonastes sp. within the consortium rose from 87 % at 300 μg/L SMX to 99.9 % at 800 μg/L SMX. while Shannon indices of the bacterial community increased from 1.415 to 2.867. This shift inhibited the initially dominant Saprospiraceae bacteria, facilitating the profound increase of adapted Aquimonas. These findings demonstrate the feasibility of the simultaneous removal of antibiotics and nutrients from wastewater with a microalgae consortium system.

Assessment of photocatalytic activities of layered double hydroxide@petrochemical sludge biochar for sulfamethoxazole degradation

Layered double hydroxides (LDHs) as one of the popular photocatalysts have the drawbacks of compact structural arrangement and pronounced nano-particle clustering, which affect their photocatalytic performance for the degradation of organic pollutants from water or wastewater. Using biochar as a substrate matrix to support LDHs may be a good way to improve the photocatalytic performance of LDHs by avoiding agglomeration effect, promoting the separation of photogenerated electrons from holes for organics degradation. In this study, the composite of CoFe-LDH and petrochemical sludge biochar (CoFe-LDH@PBC) was fabricated and applied for the first time as photocatalyst for catalytic degradation of sulfamethoxazole (SMX). Results showed CoFe-LDH@PBC800/UV system exhibited excellent photocatalytic activity on SMX degradation than single CoFe-LDH/UV, PBC800/UV, or PBC105/UV system under various reaction conditions (photocatalyst dosage, pH, system speed, and SMX concentration). 100 % of SMX degradation efficiency and 88.98 % mineralization efficiency could be achieved in CoFe-LDH@PBC800/UV system within 100 min. The corresponded pseudo-first-order kinetic rate constant (kobs) of SMX degradation in CoFe-LDH@PBC800/UV system was 0.032 min−1, which was 3.20, 8.00, and 2.46 times higher than that of CoFe-LDH/UV, PBC800/UV, and PBC105/UV, respectively. In photocatalytic process, OH, O2−, and h+ participated in SMX degradation, among which h+ or OH played a major role. The good photocatalytic performance of CoFe-LDH@PBC800 composite was related to its excellent physiochemical properties, such as lower band gap (2.39 eV), high graphitization degree, and high conductivity, enabling efficient e−/h+ separation of photocatalyst for SMX degradation. Four distinct pathways of SMX degradation were proposed based on DFT theoretical calculations and byproducts of SMX degradation identified by LC-MS. Additionally, results from recycling tests suggested CoFe-LDH@PBC800 composite possessed a favorable reusability and could be applied for photocatalytic degradation of SMX at least 3 times. Over all, CoFe-LDH@PBC800 composite was proved to be an efficient photocatalyst for antibiotic degradation in water or wastewater and the reuse of petrochemical wastewater sludge was expected to realize the concept of resourceful and high-value utilization of waste biomass.

Anaerobic dynamic membrane bioreactor treating sulfamethoxazole wastewater: advantages of dynamic membrane and its fouling mechanism

Discharge of improperly treated sulfamethoxazole (SMX) wastewater seriously threats environmental security and public health. Anaerobic dynamic membrane bioreactors (AnDMBRs) technology would be cost-effective for SMX wastewater treatment, considering its low cost and satisfactory treatment efficiency. The performance of AnDMBR, though demonstrated to be excellent in treating many types of wastewaters, was for the first time investigated for treating SMX wastewater. Particular efforts were devoted to elucidating the advantages of dynamic membrane (DM) and the governing mechanism responsible for DM fouling with the presence of SMX. The threshold SMX concentration for AnDMBR was found to be 90 mg/L and the AnDMBR exhibited excellent removal efficiency of COD (90.91 %) and SMX (88.95 %) as well as satisfactory acute toxicity reduction rate (88.84 %). It was noteworthy that the DM made indispensable contributions to the removal of COD (14.26 %) and SMX (22.20 %) as well as the acute reduction of toxicity (25.81 %). The presence of SMX significantly accelerated DM fouling mainly by increasing its specific resistance, which was attributed to the increased content of small particles, high-valence metal ions and EPS content (mainly hydrophobic proteins), resulting in a denser DM structure with lower porosity. Besides, the biofouling-related bacteria (Firmicutes) was found to be enriched in the DM with the presence of SMX.

Opposite Effects of Planting on Antibiotic Resistomes in Rhizosphere Soil with Different Sulfamethoxazole Levels.

Achieving consensus about the rhizosphere effect on soil antibiotic resistomes is challenging due to the variability in antibiotic concentrations, sources, and the elusory underlying mechanisms. Here, we characterized the antibiotic resistomes in both the rhizosphere and bulk soils of soybean plants grown in environments with varying levels of antibiotic contamination, using sulfamethoxazole (SMX) as a model compound. We also investigated the factors influencing resistome profiles. Soybean cultivation altered the structure of antibiotic-resistant genes (ARGs) and increased their absolute abundance. However, the rhizosphere effect on the relative abundance of ARGs was dependent on SMX concentrations. At low SMX levels, the rhizosphere effect was characterized by the inhibition of antibiotic-resistant bacteria (ARBs) and the promotion of sensitive bacteria. In contrast, at high SMX levels, the rhizosphere promoted the growth of ARBs and facilitated horizontal gene transfer of ARGs. This novel mechanism provides new insights into accurately assessing the rhizosphere effect on soil antibiotic resistomes.

Combined effects of polyamide microplastic and sulfamethoxazole in modulating the growth and transcriptome profile of hydroponically grown rice (Oryza sativa L.)

The use of reclaimed water from wastewater treatment plants for irrigation has a risk of introducing micropollutants such as microplastics (MPs) and antimicrobials (AMs) into the agroecosystem. This study was conducted to investigate the effects of single and combined treatment of 0.1 % polyamide (PA ∼15 μm), and varying sulfamethoxazole (SMX) levels 0, 10, 50, and 150 mg/L on rice seedlings (Oryza sativa L.) for 12 days. The study aimed to assess the impact of these contaminants on the morphological, physiological, and biochemical parameters of the rice plants. The findings revealed that rice seedlings were not sensitive to PA alone. However, SMX alone or in combination with PA, significantly inhibited shoot and root growth, total biomass, and affected photosynthetic pigments. Higher concentrations of SMX increased antioxidant enzyme activity, indicating oxidative stress. The roots had a higher SMX content than the shoots, and the concentration of minerals such as iron, copper, and magnesium were reduced in roots treated with SMX. RNA-seq analysis showed changes in the expression of genes related to stress, metabolism, and transport in response to the micropollutants. Overall, this study provides valuable insights on the combined impacts of MPs and AMs on food crops, the environment, and human health in future risk assessments and management strategies in using reclaimed water.

Sulfamethoxazole exposure shifts partial denitrification to complete denitrification: Reactor performance and microbial community

This study elucidated the influence on a partial denitrification (PD) system under 0–1 mg/L sulfamethoxazole (SMX) stress in a sequencing batch reactor. The results showed that the nitrite accumulation rate (NAR) significantly (P ≤ 0.01) decreased from 68.68 ± 9.00% to 49.05 ± 11.68%, while the total nitrogen removal efficiency significantly (P ≤ 0.001) increased from 23.19 ± 4.42% to 31.36 ± 2.73% in presence of SMX. The results indicated that SMX exposure switched the PD process to complete denitrification through the deterioration of the nitrite accumulation and the promotion of further nitrite reduction. The SMX removal loading rate increased from 0.21 ± 0.04 to 5.03 ± 0.77 mg-SMX/(g-MLVSS·d) with the extended reactor operation under SMX stress. Low SMX concentration exposure increased extracellular polymeric substances (EPS) content from 107.69 ± 20.78 mg/g-MLVSS (0.05 mg-SMX/L) to 123.64 ± 9.66 mg/g-MLVSS (0.5 mg-SMX/L), while EPS secretion was inhibited under high SMX concentration exposure (i.e., 1 mg-SMX/L). Moreover, SMX exposure promoted the synthesis of aromatic protein-like compounds and changed the functional groups as revealed by EEM and FTIR analysis. Additionally, SMX exposure significantly shifted the microbial community structures at both phylum and genus levels. Particularly, the abundance of Thauera, i.e., functional bacteria related to PD, considerably decreased from 41.69% to 11.62% after SMX exposure, whereas the abundances of Denitratisoma and SM1A02 significantly rose under different SMX concentrations. These outcomes hinted that the addition of SMX resulted in the shifting of partial denitrification to complete denitrification.

Highly sensitive chemiluminescent sensor for detecting o-toluenesulfonamide and sulfamethoxazole using Cu-doped carbon dots

In this study, Cu doped carbon dots (Cu-CDs) of uniform particle size and good water solubility was synthesized using Angelica Sinensis Radix as precursor materials through a one-step hydrothermal. The Lucigenin-(Cu-CDs) chemiluminescence sensor allows the simultaneous determination of o-toluenesulfonamide (TFA) and sulfamethoxazole (STZ) concentrations. Under optimal conditions, the sensor demonstrates the capability to detect TFA and STZ within the ranges of 50 μM–800 μM and 15 μM–120 μM, respectively. The limits of detection (LOD) for TFA and STZ are determined as 0.09 μM and 0.05 μM, respectively. While the limits of quantification (LOQ) are established at 0.3 μM and 0.17 μM, respectively. The feasibility of the method for determining TFA and STZ content in chicken samples was substantiated, demonstrating spiked recovery rates ranging from 97.5% to 102.3 % and 97.5%–99.8 %, respectively. The possible reaction mechanism was clarified based on chemiluminescence, UV–vis measurement and free radical analysis results. The newly established system is characterized by stability, convenience, and robust anti-interference capabilities, thus expanding the application of carbon dots and offering a promising strategy for the detection of TFA and STZ.

CdSe nanoflower as a new near infrared-activated photocatalyst for remediation of pharmaceutical wastewaters

Photocatalysis using Near Infrared (NIR) light is a promising method for a wide range of applications from environmental remediation. For this purpose, a flower-like cadmium selenide (CdSe nanoflower), as a new promising NIR-activated photocatalyst, was synthesized through a hydrothermal process and characterized using various spectroscopic and microscopic analytical techniques. The characterization results indicated that CdSe nanoflower is classified as an n-type semiconductor with a direct band gap of 1.7 eV (i.e., ECB = −0.7 V and EVB = 1 V indicated by Mott-Schottky analysis), and crystallite size and strain of 9.17 nm and 2.14, respectively. In the presence of various scavengers, the production of reactive oxygen species decreases, resulting in lower degradation efficiency. To investigate the photocatalytic efficacy, sulfamethoxazole (SMX) was used as a model pollutant drug molecule. The optimization of the process revealed that over 98% of SMX could be degraded under NIR irradiation and optimal conditions (pH = 7, photocatalyst dosage = 0.1 g, SMX concentration = 40 mg/L, time = 60 min), where Lagergren model with a correlation coefficient of 0.9765 was the best kinetic model describing the empirical results. The study indicates that CdSe nanoflower can be reused and regenerated up to 7 times with a 12% decrease in performance and after 60 min of degradation, the TOC concentration decreased by 81% in the best conditions. Additionally, CdSe nanoflower showed photodynamic microbial inactivation efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under NIR light irradiation, where almost 95 and 99 % of bacteria was reduced in 20 min. The results of this work show CdSe nanoflower has great potential as a photocatalytic material with antimicrobial properties in the context of wastewater treatment and the management of microbial infections.

Population Pharmacokinetics of Trimethoprim/Sulfamethoxazole: Dosage Optimization for Patients with Renal Insufficiency or Receiving Continuous Renal Replacement Therapy.

The goal of the study was to describe the population pharmacokinetics of trimethoprim, sulfamethoxazole, and N-acetyl sulfamethoxazole in hospitalized patients. Furthermore, this study used the model to optimize dosing regimens of cotrimoxazole for Pneumocystis jirovecii pneumonia and in patients with renal insufficiency or with continuous renal replacement therapy (CRRT). This was a retrospective multicenter observational cohort study based on therapeutic drug monitoring (TDM) data from hospitalized patients treated with cotrimoxazole. We developed two population pharmacokinetic (POPPK) models: a model of trimethoprim and an integrated model with both sulfamethoxazole and N-acetyl sulfamethoxazole concentrations. Monte Carlo simulations were performed to determine the optimal dosing regimen. A total of 348 measurements from 168 patients were available. The estimated glomerular filtration rate (eGFR) and CRRT were included as covariates on the clearance of all three compounds. Cotrimoxazole TID 1,920 mg and b.i.d. 2,400 mg led to sufficient exposure for infections with P. jirovecii in patients without renal insufficiency. To reach equivalent exposure, a dose reduction of 33.3% is needed in patients with an eGFR of 10 mL/minute/1.73 m2 and of 16.7% for an eGFR of 30 mL/minute/1.73 m2. N-acetyl sulfamethoxazole accumulates in patients with a reduced eGFR. CRRT increased the clearance of sulfamethoxazole, but not trimethoprim or N-acetyl sulfamethoxazole, compared with the median clearance in the population. Doubling the sulfamethoxazole dose is needed for patients on CRRT to reach equivalent exposure.

Catalytic micro-structured ceramic beads and efficacy evaluation through SMX degradation in PMS-activated systems

This study tackles the challenge of applying fine and nano-catalyst particles in Advanced Oxidation Processes (AOPs), primarily due to the complexities of nanoparticle removal from treated water to prevent secondary nano-hazards. We propose an innovative solution: micro-structured ceramic beads (MSCBs, approximately 3 mm in diameter) with a unique anisotropic pore structure. For the first time, we prepared MSCBs impregnated with cobalt oxide (Co/MSCBs) using a phase-inversion and sintering-assisted process. The Co/MSCBs were investigated for the degradation of sulfamethoxazole (SMX) in the peroxymonosulfate (PMS) induced AOPs system under mild reaction conditions. The effects of operating parameters (e.g., SMX concentration, reaction temperature, and catalyst dosage) in the Co/MSCBs|PMS system were studied on three different types of catalytic ceramic beads: 2Co/MSCB0 (beads with a common isotropic pore structure), 2Co/MSCB1 (beads with radial finger-like microstructures and a denser outer skin-layer), and 2Co/MSCB2 (beads with finger-like microstructures and no outer skin layer). At 20 °C, 2Co/MSCB2 (59.1 %) demonstrated a higher degradation efficiency for 40 mg/L SMX in comparison to 2Co/MSCB1 (54.9 %) and 2Co/MSCB0 (49.6 %). Additionally, it is noteworthy that the sample 2Co/MSCB2, after being used and regenerated, exhibited significantly a higher catalytic performance (70.83 % removal in 20 min during the 16th run) than the fresh one (70.47 % removal in 120 min). After reactions, Co/MSCBs can be readily separated from the bulk solution and used for the next run, making them ideal for practical applications. Furthermore, a radical quenching experiment was conducted, and a plausible catalytic mechanism was proposed. This research presents a new approach for the fabrication of micro-structured ceramic beads that are capable of effectively overcoming the diffusion limitations encountered in both heterogeneous reactions and adsorption processes.

Phytoremediation of diclofenac and sulfamethoxazole in Arabidopsis thaliana cells and seedlings

Diclofenac (DLF), a widely recognized non-steroidal anti-inflammatory drug (NSAID), and sulfamethoxazole (SMX), a broad-spectrum sulfonamide antibiotic, are commonly prescribed medications that have raised concerns as significant contributors to pharmaceutical pollution in natural ecosystems despite their clinical effectiveness. This study investigates the potential phytoremediation pathways for these two drugs in plant systems by tracking and quantifying the fate of the parent compounds and their metabolites in Arabidopsis thaliana using cell and seedling cultures. Results indicated significant differences in the dissipation of DLF according to the treatment and time interaction within the cell cultures. Viable plant cells showed complete dissipation of DLF from an initial concentration of 2758 ng/mL in 96 h, whereas non-viable cells and blank solutions remained stable. The dissipation of SMX was comparable across viable, non-viable, and blanks, showing a minor decrease from 842 to 799 ng/mL over 120 h following the treatment of viable cells. DLF metabolites including 4′-hydroxy-diclofenac, 5-hydroxy-diclofenac, acyl-glutamatyl-diclofenac, 1-(2,6-dichlorophenyl)-5-hydroxy-2-indolinone, 5-sulfooxy-diclofenac, 5-glucopyranosyloxy-diclofenac, 1-(2,6-dichloro-4-hydroxyphenyl)-2-indolinone, and 4′-glucopyranosyloxy-diclofenac were recognized, likely formed through acylation, glutamyl conjugation, hydroxylation, dehydration, cyclization, sulfonation, and glucosidation. While for SMX, metabolites including sulfamethoxazole-glucuronide, nitroso-sulfamethoxazole, N4-acetylsulfamethoxazole, and N4-acetyl-5-OH-sulfamethoxazole were identified, potentially produced through glucuronidation, nitrosation, acetylation, and hydroxylation. Phase I metabolite concentrations of DLF and SMX peaked earlier than those of phase II metabolites. Hydroponic A. thaliana demonstrated comparable efficiencies in the phytoremediation of DLF and SMX, with concentrations varying from 1 mg/L to 10 mg/L. Detectable levels of both parent compounds and their metabolites confirmed successful absorption and metabolism within the plant system. This study provides valuable insights into the potential of phytoremediation as a sustainable approach for reducing the environmental toxicity of DLF and SMX and suggests comparable metabolic efficiency. These findings contribute to the growing body of knowledge on phytoremediation and its application in addressing pollution from pharmaceuticals and personal care products.

Hydroxylamine-induced activation of permanganate for enhanced oxidation of sulfamethoxazole: Mechanism and products

Recently, many reagents have been introduced to accelerate the formation of highly reactive intermediate Mn species from permanganate (KMnO4), thereby improving the oxidation activity of KMnO4 towards pollutants. However, most studies have mainly focused on sulfur-containing reducing agents (e.g., bisulfite and sodium sulfite), with little attention paid to nitrogen-containing reducing agents. This study found that hydroxylamine (HA) and hydroxylamine derivatives (HAs) can facilitate KMnO4 in pollutant removal. Taking sulfamethoxazole (SMX) as a target contaminant, the effect of pH, SMX concentration, KMnO4 and HA dosages, and the molar ratio of HA and KMnO4 on the degradation of SMX in the KMnO4/HA process was systematically investigated. Quenching experiments and probe analysis revealed MnO2-catalyzed KMnO4 oxidation, Mn(III) and reactive nitrogen species as the primary active species responsible for SMX oxidation in the KMnO4/HA system. Proposed transformation pathways of SMX in the KMnO4/HA system mainly involve hydroxylation and cleavage reactions. The KMnO4/HA system was more conducive to selective oxidation of SMX, 2,4-dichlorophenol, and several other pollutants, but reluctant to bisphenol S (BPS). Overall, this study proposed an effective system for eliminating pollutants, while providing mechanistic insight into HA-driven KMnO4 activation for environmental remediation.

Are pharmaceutical residues in crops a threat to human health?

ABSTRACT The application of biosolids, manure, and slurry onto agricultural soils and the growing use of treated wastewater in agriculture result in the introduction of human and veterinary pharmaceuticals to the environment. Once in the soil environment, pharmaceuticals may be taken up by crops, resulting in consequent human exposure to pharmaceutical residues. The potential side effects of pharmaceuticals administered in human medicine are widely documented; however, far less is known regarding the risks that arise from incidental dietary exposure. The aim of this study was to evaluate human exposure to pharmaceutical residues in crops and assess the associated risk to health for a range of pharmaceuticals frequently detected in soils. Estimated concentrations of carbamazepine, oxytetracycline, sulfamethoxazole, trimethoprim, and tetracycline in soil were used in conjunction with plant uptake and crop consumption data to estimate daily exposures to each compound. Exposure concentrations were compared to Acceptable Daily Intakes (ADIs) to determine the level of risk. Generally, exposure concentrations were lower than ADIs. The exceptions were carbamazepine, and trimethoprim and sulfamethoxazole under conservative, worst-case scenarios, where a potential risk to human health was predicted. Future research therefore needs to prioritize investigation into the health effects following exposure to these compounds from consumption of contaminated crops.

Application of Membrane Bioreactor (MBR) for Antibiotic Elimination From Wastewater

In this study, a membrane bioreactor – MBR system at laboratory-scale was designed to remove sulfamethoxazole (SMX) in water. The system consists of a 8-liter aerobic tank combined with a hollow fiber micro filtration membrane (MF). Influent flow rate of wastewater was 15,84 L/day. Affecting factors to treatment efficiencies (organic pollutants and antibiotics) such as contact time and initial antibiotic concentration were investigated. Experimental results indicated that wastewater with initial parameters COD, NH4+, NO3-, PO43- were respectively 240, 9,4, 37,5, 6,3 mg/L, the treatment efficiencies achieved were respectively at 63,4, 89,7, 78,1, and 79,8%. The removal efficiencies of the wastewater containing SMX (concentrations range from 0,052 to 0,268 mg/L) for COD and NH4+ decreased by 4,2 and10,9% respectively, and for NO3- and PO43- increased by about 4,5 and 7,9%, correspondingly. Overall SMX elimination performance is about 49,7%.

Biodegradation of Photocatalytic Degradation Products of Sulfonamides: Kinetics and Identification of Intermediates.

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 TiO2-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.

S-scheme Bi/Bi2WO6/TiO2 nanofiber photocatalyst for efficient degradation of sulfamethoxazole

Improving the efficiency of photogenerated carrier separation by designing heterojunction photocatalysts remains an important challenge. In this study, TiO2 nanofibers were prepared by electrospinning, Bi/Bi2WO6/TiO2 heterojunctions were constructed by hydrothermal method, and verified by characterization techniques. The heterojunction had good photodegradation activity to sulfamethoxazole (SMX) under ultraviolet and visible light irradiation (96.4 % within 60 min). The enhanced photodegradation activity of Bi/Bi2WO6/TiO2 nanocomposites can be attributed to the synergistic effect of S-Scheme mechanism and Bi metal plasma action. In addition, Bi metals can generate a large number of electron-hole pairs under the action of surface plasmon resonance (SPR). In addition, the influence factors such as pH, SMX concentration and catalyst loading were studied. According to the detected intermediates, the photocatalytic degradation pathway of SMX was studied. The results of free radical capture experiment and ESR show that ·O2– and h+ free radicals play an important role in the decomposition of SMX. The cyclic experiments show that Bi/Bi2WO6/TiO2 nanocomposites have excellent stability and reuse characteristics. Finally, the mechanism of photocatalytic degradation of SMX was described. This study provides a promising perspective for the preparation and development of S-Scheme heterojunction photocatalysts based on Bi2WO6.

Cellulose-based Co[sbnd]Fe LDH composite as a nano-adsorbent for sulfamethoxazole and cefixime residues: Evaluation of performance, green metrics and cytotoxicity

The increase in antibiotic residues poses a serious threat to ecological and aquatic environments, necessitating the development of cost-effective, convenient, and recyclable adsorbents. In our study, we used cellulose-based layered double hydroxide (LDH) as an efficient adsorbent and nanocarrier for both sulfamethoxazole (SMX) and cefixime (CFX) residues due to their biodegradability and biocompatibility. Chemical processes are measured according to green chemistry metrics to identify which features adhere to the principles. A GREEnness Assessment (ESA), Analytical GREEnness Preparation (AGREEprep), and Analytical Eco-Scale Assessments (ESA) were used to assess the suitability of the proposed analytical method. We extensively analyzed the synthesized CoFe LDH/cellulose before and after the adsorption processes using XRD, FTIR, and SEM. We investigated the factors affecting the adsorption process, such as pH, adsorbent dose, concentrations of SMX and CFX and time. We studied six nonlinear adsorption isotherm models at pH 5 using CoFe LDH, which showed maximum adsorption capacities (qmax) of 272.13 mg/g for SMX and 208.00 mg/g for CFX. Kinetic studies were also conducted. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed on Vero cells in direct contact with LDH nanocomposites to evaluate the cytotoxicity and side effects of cellulose-based CoFe LDH. The cellulose-based CoFe LDH nanocomposite demonstrated excellent cytocompatibility and less cytotoxic effects on the tested cell line. These results validate the potential use of these unique LDH-based cellulose cytocompatible biomaterials for water treatment applications. The cost of the prepared adsorbents was investigated.

Synthesis, characterization, and electrochemical application of novel poly(Cu2P4BCl4) based glassy carbon electrodes for determination of sulfamethoxazole in pharmaceutical serum and urine samples and Cow’s milk

The synthesis of the novel complex, [Cu2P4B]Cl4·H2O (in short Cu2P4BCL4), was confirmed by UV–Vis and FT-IR data after a straightforward ion exchange reaction. The electrochemical fabrication of the Nobel Cu2P4BCl4-based GCE was done potentiodynamically by scanning the potential of the glassy carbon electrode on the buffer solution containing 1.0 mM Cu2P4BCl4. EIS and CV were employed to characterize the surface of the developed sensor. The electroactive area and charge transfer capacity of the modified electrode were improved by about 2.5-fold area and 100-fold double-layer capacitor, respectively. The electrochemical activity of the Sulfamethoxazole (SMX) on the developed electrode was improved at around 3.1-fold peak intensities. The poly(Cu2P4BCl4)/GCE showed a wide linear range of the concentration of SMX from 0.1 to 200 µM at pH 6.5. The LOD and LOQ of the developed sensor were 0.112 nM and 0.375 nM, respectively, with the associated %RSD of 0.26 % (for n = 7). The validation of the real application of the fabricated electrode for the determination of SMX was investigated by detecting the cow’s milk sample, serum, and urine samples with spike recovery in the range of 97.5–103 %. The selectivity of the developed sensor towards SMX in the presence of potential interferants revealed an excellent recovery percentage in the range of 98.66–102.7 % in the presence of 50 to 200 % of potential interferents indicating an excellent accuracy and selectivity of the sensor. The stability and reproducibility of the Nobel sensor were investigated and revealed the best means for electrochemical determination of SMX from real cow’s milk, serum, and urine samples.