Sulfamethazine Concentration Research Articles

Enhanced release of volatile halocarbons of microalgae in response to antibiotic-induced stress: Based on laboratory and ship-field experiments

This study investigated the impacts of sulfamethazine (SMZ) and oxytetracycline (OTC) antibiotics on the marine microalgae Nitzschia closterium and its release of volatile halocarbons (VHCs), which contribute to ozone depletion and climate change. High concentrations of SMZ and OTC suppressed cell density, reduced chlorophyll a content, and hindered Fv/Fm elevation in N. closterium, indicating its growth was inhibited. The exposure of N. closterium to antibiotics led to increased reactive oxygen species (ROS), reduced soluble protein content, and heightened catalase (CAT) activity, indicative of increased oxidative stress. This stress increased the release of three VHCs (CHBrCl2, CHBr2Cl, and CHBr3). Ship-borne experiments showed that high phytoplankton biomass was linked to high VHC release. Notably, the production and release of VHCs were significantly higher in the high-concentration antibiotic group (100 μg/L) than the low-concentration group (0.1 μg/L). These findings suggested that antibiotics induce excess ROS in algal cells, stimulating VHC production and release.

Effects of sulfamethazine and tetracycline at molecular, cellular and tissue levels in Eisenia fetida earthworms

Soil contamination by antibiotics is a global issue of great concern that contributes to the rise of bacterial antibiotic resistance and can have toxic effects on non-target organisms. This study evaluated the variations of molecular, cellular, and histological parameters in Eisenia fetida earthworms exposed to sulfamethazine (SMZ) and tetracycline (TC), two antibiotics commonly found in agricultural soils. The earthworms were exposed for 14 days to a series of concentrations (0, 10, 100, and 1000 mg/kg) of both antibiotics. SMZ and TC did not affect the survival of E. fetida, however, other effects at different levels of biological complexity were detected. The two highest concentrations of SMZ reduced the viability of coelomocytes. At the highest TC concentration, there was a noticeable decline in cell viability, acetylcholinesterase activity (neurotoxicity), and the relative presence of mucopolysaccharides in the epidermis (mucous production). Glutathione S-transferase activity decreased in all TC treatments and at the highest SMZ concentration. However, levels of malondialdehyde and protein carbonyls did not change, suggesting an absence of oxidative stress. Tetracycline was neurotoxic to E. fetida and changed the integrity of the epidermis. Both antibiotics altered the intestinal microbiota of E. fetida, leading to a reduction in the relative abundance of bacteria from the phyla Proteobacteria and Bacteroidetes, while causing an increase in the phylum Actinobacteroidota. All observed changes indicate that both SMZ and TC can disrupt the earthworms' immune system and gut microbiome, while fostering the growth of bacteria that harbour antibiotic resistance genes. Finally, both antibiotics exerted additional metabolic and physiological effects that increased the vulnerability of E. fetida to pathogens.

Fluoranthene slow down sulfamethazine migration in soil via π-π interaction to increase the abundance of antibiotic resistance genes

Sulfonamide antibiotics and polycyclic aromatic hydrocarbons (PAHs) often coexist in soil, leading to compound pollution through various pathways. This study focuses on sulfamethazine (SMZ) and PAHs (fluoranthene) as the subject for compound pollution research. Using a soil-groundwater simulation system, we investigated the migration characteristics of SMZ under coexistence with fluoranthene (Fla) and observed variations in the abundance of antibiotic resistance genes (ARGs). Through molecular docking simulations and isothermal adsorption experiments, we discovered that Fla bound with SMZ via π−π interactions, resulting in a 20.9% increase in the SMZ soil-water partition coefficient. Under compound conditions, the concentration of SMZ in surface soil could reach 1.4 times that of SMZ added alone, with an 13.4% extension in SMZ half-life. The deceleration of SMZ's vertical migration rate placed additional stress on surface soil microbiota, leading to a proliferation of ARGs by 66.3%–125.8%. Moreover, under compound pollution, certain potential hosts like Comamonadaceae and Gemmatimonas exhibited a significant positive correlation with resistance genes such as sul 1 and sul 2. These findings shed light on the impact of PAHs on sulfonamide antibiotic migration and the abundance of ARGs. They also provide theoretical insights for the development of technologies aimed at mitigating compound pollution in soil.

Effects of four antibiotics on the photosynthetic light reactions in the green alga Chlorella pyrenoidosa

Antibiotics are ubiquitously present in aquatic environments, posing a serious ecological risk to aquatic ecosystems. However, the effects of antibiotics on the photosynthetic light reactions of freshwater algae and the underlying mechanisms are relatively less understood. In this study, the effects of 4 representative antibiotics (clarithromycin, enrofloxacin, tetracycline, and sulfamethazine) on a freshwater alga (Chlorella pyrenoidosa) and the associated mechanisms, primarily focusing on key regulators of the photosynthetic light reactions, were evaluated. Algae were exposed to different concentrations of clarithromycin (0.0–0.3 mg/L), enrofloxacin (0.0–30.0 mg/L), tetracycline (0.0–10.0 mg/L), and sulfamethazine (0.0–50.0 mg/L) for 7 days. The results showed that the 4 antibiotics inhibited the growth, the photosynthetic pigment contents, and the activity of antioxidant enzymes. In addition, exposure to clarithromycin caused a 118.4 % increase in malondialdehyde (MDA) levels at 0.3 mg/L. Furthermore, the transcripts of genes for the adenosine triphosphate (ATP) - dependent chloroplast proteases (ftsH and clpP), genes in photosystem II (psbA, psbB, and psbC), genes related to ATP synthase (atpA, atpB, and atpH), and petA (related to cytochrome b6/f complex) were altered by clarithromycin. This study contributes to a better understanding of the risk of antibiotics on primary producers in aquatic environment.

Voltametric Sensor Based on Magnetic Chitosan Acetylindole-Based Nanocomposite for the Determination of Sulfamethazine.

Sulfamethazine (SMZ), a persistent antibiotic, is frequently detected in drinking water and milk. For this reason, our research aimed to develop a novel electrochemical sensor based on a magnetic nanocomposite supported on chitosan modified by 3-acetylindole through the formation of chitosan acetylindole Schiff base (Chs-Aci). The objective was to detect extremely low concentrations of SMZ in milk. The synthesized nanocomposites were characterized by various techniques, including FT-IR, XRD, EDX, SEM, and TEM. To enhance the electrocatalytic efficiency for sensitive SMZ detection in food samples, a magnetic chitosan acetylindole nanocomposite (M-Chs-Aci) was employed as a modifier for a carbon paste electrode (CPE). The electrochemical measurements revealed that the M-Chs-Aci/CPE exhibits good electrocatalytic performance compared to a bare CPE. Moreover, low detection limit, repeatability, and stability were achieved at 0.021 μM, 3.83%, and 94.87%, respectively. Finally, the proposed M-Chs-Aci/CPE proved to be highly effective in detecting SMZ in milk samples. The obtained findings paved the way for the effective usability of M-Chs-Aci/CPE as a sensor for detecting SMZ in real samples, with acceptable recoveries of 95%-98.87%.

Novel Eu-dipeptide assemblies for a fluorescence sensing strategy to ultrasensitive determine trace sulfamethazine

Self-assembled Eu-dipeptide (tryptophan-phenylalanine) microparticles with multi-emission fluorescence was prepared and modified with a single-stranded DNA corresponding to the sulfamethazine (SMZ) adapter (Eu-PMPs@cDNA). Aptamer-functionalized magnetic Fe3O4 (MNPs@aptamer) was used to specifically bind the target SMZ. Using Eu-PMPs@cDNA as fluorescent signal probe and MNPs@aptamer as catcher, a noncompetitive fluorescence sensing strategy was developed for determination of SMZ with good sensitivity, accuracy, selectivity, and stability. Under the optimized conditions, fluorescence increases linearly in the 0–20 ng/mL SMZ concentration range, and the detection limit is 0.014 ng/mL. The fluorescence sensing method was applied to analysis of water and fish muscle samples, and recoveries ranged from 81.78 to 119.46 % with relative standard deviations below 4.2 %. This study offered a reliable and sensitive fluorescence sensing strategy for SMZ determination in food samples, which owns great potential for wide-ranging application in harmful compounds assay by simply changing the type of aptamer and its complementary single-stranded DNA.

Simultaneous removal of As(V) and sulfamethazine from water in FeS2-H2O2 system

Sulfamethazine (SMT) and organic arsenic are usually used as feed additives in animal husbandry and aquaculture, which will produce severe compound pollution after metabolism and discharge. In this work, the FeS2-H2O2 system was used to simultaneously remove As(V) and SMT. Under 0.8 g/L of FeS2, 40 mM of H2O2, the simultaneous removal efficiency of SMT and As(V) was up to 97 %. The initial concentration of As(V) was unfavourable for SMT degradation, while the effect of initial concentration of SMT on As(V) removal could be ignored. Meanwhile, increasing FeS2 and H2O2 dosages enhanced removal efficiency of SMT and As(V). However, excessive FeS2 was detrimental to the removal of As, and the ·OH, ·O2−, and 1O2 were generated to degrade SMT. As was adsorbed on the surface of positively charged FeS2 firstly and then reacted with Fe(III) on the surface of FeS2 or released by Fenton reaction to form FeAsO4. No As(III) was detected during the simultaneous removal process in the FeS2-H2O2 system. This study revealed that SMT and As(V) could be removed simultaneously in the FeS2-H2O2 system, which produced new insight into animal husbandry and aquaculture wastewater treatments.

Antimicrobials in Eisenia fetida earthworms: A comprehensive study from method development to the assessment of uptake and degradation

In this work, an accurate analytical method was developed for the simultaneous analysis of twenty-seven antimicrobials (AMs) in earthworms using liquid chromatography coupled to a triple quadrupole mass spectrometry detector (UHPLC-MS/MS). Adequate apparent recoveries (80–120 %) and limits of quantification (LOQ) (1 μg·kg−1 - 10 μg·kg−1) were obtained, with the exception of norfloxacin (34 μg·kg−1). The method was applied to evaluate the accumulation of sulfamethazine (SMZ) and tetracycline (TC) in earthworms after performing OECD-207 toxicity test, in which Eisenia fetida (E. fetida) organisms were exposed to soils spiked with 10 mg·kg−1, 100 mg·kg−1 or 1000 mg·kg−1 of SMZ and TC, individually. The results confirmed the bioaccumulation of both AMs in the organisms, showing a greater tendency to accumulate SMZ since higher bioconcentration factor values were obtained for this compound at the exposure concentrations tested. In addition, the degradation of both AMs in both matrices, soils and earthworms was studied using liquid chromatography coupled to a q-Orbitrap high resolution mass spectrometry detector. Thirteen transformation products (TPs) were successfully identified, eight of them being identified for the first time in soil/earthworm (such as 4-Amino-3-chloro-n-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide or 4-(dimethylamino)-1,11,12a-trihydroxy-6,6-dimethyl-3,7,10,12-tetraoxo-3,4,4a,5,5a,6,7,10,12,12a-decahydrotetracene-2-carboxamide, among others) and their formation/degradation trend over time was also studied. Regarding the biological effects, only SMZ caused changes in earthworm growth, evidenced by weight loss in earthworms exposed to concentrations of 100 mg·kg−1 and 1000 mg·kg−1. Riboflavin decreased at all concentrations of SMZ, as well as at the highest concentration of TC. This indicates that these antibiotics can potentially alter the immune system of E. fetida. This research represents a significant advance in improving our knowledge about the contamination of soil by AM over time. It investigates the various ways in which earthworms are exposed to AMs, either by skin contact or ingestion. Furthermore, it explores how these substances accumulate in earthworms, the processes by which earthworms break them down or metabolise them, as well as the resulting TPs. Finally, it examines the potential effects of these substances on the environment.

Spinel ZnMn2O4 nanosphere for the efficient Sulfamethazine degradation under visible light irradiation and photoelectrochemical study

This study assessed the efficacy of ZnMn2O4 (ZMO) spinel structure, synthesized via the solvothermal method, as a photocatalyst for the efficient photocatalytic degradation of Sulfamethazine (SMT) under visible light conditions. Comprehensive analyses involving FESEM, TEM, EDX, XRD, Raman, FTIR, XPS, and BET have been conducted, and the results strongly supported the successful preparation of ZMO. The optical characteristics of the as-synthesised sample was assessed using UV–VIS DRS, which indicated a band gap that was conducive to the effective absorption of visible light. Mott-Schottky (M-S) plot, Electrochemical Impedance Spectroscopy (EIS) analysis and photocurrent study have been utilised for knowing the type of semiconductor, kinetic charge transfer and charge separation and transfer within the on and off areas respectively. Degradation of SMT has been done in a suitable photochemical reactor and reaction rate constant has been evaluated. The study employed RSM modelling with Box-Behnken design to optimise various operational parameters in a photocatalytic reaction. These parameters included solution pH, dosage of ZMO, and initial concentration of SMT. Following a duration of 60 minutes under ideal circumstances, the residual concentration of SMZ declined to a level that is no longer detectable. The utilisation of tandem mass spectrometry has been employed to discover the transition products and their existence has been subsequently utilised to propose a degradation pathway.

Evaluation of kinetic constants uncertainty for the metrologically sound comparison of photodegradation efficiency using TiO2 catalysts

The comparison of the efficiency of a pair of catalysts for the photodegradation of a compound in the same irradiation conditions is affected by many independent and correlated random and systematic effects. These comparisons become objective and indisputable if the efficiency difference is estimated with uncertainty, producing an interval encompassing the “true” difference value with a known probability. This work presents a tool for the detailed evaluation of the uncertainty of estimated kinetic constant values and differences by the Monte Carlo Method simulation of all relevant uncertainty components. First-order kinetics were quantified from regression of the concentrations of studied compounds over various degradation times. The efficiency of methylene blue (MB) and sulfamethazine (SMZ) photodegradation using various solid-state catalysts was quantified and compared. Synthesised TiO2 nanoparticles are more efficient than the purchased TiO2 for MB degradation. For SMZ degradation, ruthenium-doped titanate nanowires and ruthenium-doped titanate nanotubes are equally efficient and more efficient than pristine titanate nanowires. The efficiency equivalence can be challenged by quantifying larger and/or less uncertain SMZ concentrations. First-order kinetics was tested by taking the simulated confidence limits of the intercept of the linear regression used to describe this kinetic order. Kinetic constants with asymmetric distribution and a relative expanded uncertainty for a 95 % confidence level between 3.6% and 17% were quantified. Three successively more uncertain procedures for preparing calibrators for the quantification of MB by UV/Vis spectroscopy were tested, concluding that since the same calibration curve is used to quantify all MB solutions, kinetic quantification is not proportionally or significantly affected by this uncertainty component.

Degradation of sulfamethazine in water in thermally activated persulfate process

BackgroundThe thermally activated persulfate (TAP) process was utilized to degrade sulfamethazine in water. MethodsThe effects of temperature, Na2S2O8 dosage, initial concentration of sulfamethazine, and the presence of salt (NaCl and NaNO3) and natural organic matter (humic acid) on the degradation of sulfamethazine in the TAP process were studied. Significant FindingsThe degradation of sulfamethazine in the TAP process was closely fitted by a pseudo-first-order kinetic model. At pH 6, the degree and rate of degradation of sulfamethazine at 70 °C considerably surpassed those at 40 °C with diverse Na2S2O8 dosages. At 70 °C and pH 6, raising the Na2S2O8 dosage from 1 mM to 8 mM increased the degree and rate of degradation of sulfamethazine; but excess Na2S2O8 (16 mM) limited them. However, lower temperatures eliminated this limitation. The degree and rate of degradation of sulfamethazine were higher at 70 °C and pH 6 when the initial concentration of sulfamethazine was lower. The Arrhenius equation was utilized to calculate the apparent activation energy at diverse Na2S2O8 dosages. The apparent activation energy for the degradation of sulfamethazine increased from 91 kJ/mol to 150 kJ/mol as the Na2S2O8 dosage was raised from 1 mM to 8 mM. However, the apparent activation energy for the degradation of sulfamethazine was reduced to 120 kJ/mol as the Na2S2O8 dosage was raised further to 16 mM. Radical quenching tests indicate that the most important radical in the degradation of sulfamethazine at 70 °C and pH 6 was SO4•−. At 70 °C and pH 6, the presence of salt (NaCl and NaNO3) and humic acid (HA) exhibited various influences on the degradation of sulfamethazine. The degree of degradation of sulfamethazine (10 mg/L) in the TAP process (70 °C and pH 6) reached 100% at 3 min at an Na2S2O8 dosage of 8 mM with a corresponding rate constant of 1.4003 min−1. Accordingly, the TAP process can be utilized in the effective treatment of sulfamethazine-contaminated water.

Photocatalytic Degradation of the Antibiotic Sulfamethazine Using Decatungstate Anions in an Aqueous Solution: Mechanistic Approach

The aim of this study is to propose a successful method for the treatment of water contaminated by pharmaceutical pollutants through homogeneous photocatalysis in the presence of decatungstate ions (W10O324−). Sulfamethazine (SMZ), a sulfonamide antibiotic, was used as a model molecule. The results showed that SMZ could be effectively degraded with this process under simulated solar irradiation. SMZ degradation kinetics were studied with different dioxygen and SMZ concentrations, pH values, and photocatalyst masses. Optimal conditions were determined to be pH 7, [Na4W10O32] = 0.33 g/L, and [SMZ] = 13.9 mg/L under the aerated condition, resulting in 85% SMZ degradation in 240 min, using a 36W-UVA/UVB light source. Hydroxyl radicals were identified as the major contributors to SMZ elimination. Four photoproducts identified with high-performance liquid chromatography coupled with mass spectrometry were formed by the cleavage of the sulfonamide bond and the hydroxylation of both the aromatic ring and pyrimidine moiety. SMZ was completely mineralized after 90 h of irradiation in the presence of decatungstate anions. These results provided a mechanism for the photocatalytic degradation of SMZ in an aqueous solution. To sustain this mechanism, theoretical studies were carried out using density functional theory calculations. This involved Fukui functional analyses, including ring hydroxylation, C-S bond cleavage, and molecular rearrangement processes.

Adsorption of antibiotics onto low-grade charcoal in the presence of organic matter: Batch and column tests

Antibiotics contaminate diverse ecosystems and threaten human health. In ecosystems including water, sediment, and soil, the amount of antibiotics present is tiny compared to the amount of natural organic matter. However, most studies have ignored the co-presence of natural organic matter in the adsorption of target antibiotics. In this study, we quantitatively evaluated the effect of co-presenting natural organic matter on the adsorption of sulfamethazine (SMZ) through batch and column experiments using low-grade charcoal, an industrial by-product. SMZ was used as a model antibiotic compound and humic acid (HA) was used to represent natural organic matter. The co-presence of 2000 mg/L HA (400 times the concentration of SMZ) lowered the adsorption rate of SMZ from 0.023 g/mg·min to 0.007 g/mg·min, and the maximum adsorption capacity from 39.8 mg/g to 15.6 mg/g. HA blocked the charcoal's pores and covered its surface adsorption sites, which dramatically lowered its capacity to adsorb SMZ. Similar results were obtained in the flow-through column experiments, where the co-presence of natural organic matter shortened the lifetime of the charcoal. As a result, the co-presence of a relatively high concentration of natural organic matter can inhibit the adsorption of SMZ and likely other antibiotic compounds, and thus the presence of natural organic matter should be accounted for in the design of adsorption processes to treat antibiotics in water.

Photoelectrocatalytic Oxidation of Sulfamethazine on TiO2 Electrodes

The photoelectrocatalytic degradation and mineralization of sulfamethazine (SMT), a sulfonamide drug, were explored in aqueous solution. Working electrodes with TiO2 coatings on Ti substrates (TiO2/Ti) were used, which were produced by the dip coating method. TiO2 film electrodes were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) following annealing at 500 °C for 1.5 h. To photoelectrochemically characterize them, photocurrents vs. applied potential curves were used. The photoelectrocatalytic efficiency (PEC) of the TiO2/Ti electrodes regarding the oxidation of SMT has been assessed with reference to degradation and mineralization under different experimental conditions. The selected drug molecule was effectively degraded following the Langmuir–Hinshelwood (L-H) kinetic model. The degradation efficiency was shown to increase with increasing applied potential bias up to +1.5 V vs. Ag/AgCl. It was found to be more favorable in acidic environments compared to alkaline ones. A decrease in the destruction rate constant was recorded when the pH was increased from 3 to 5.6 (natural pH) and 9. The decomposition rate was shown to first increase and subsequently reach a saturation value at high concentrations of SMT, indicating that the degradation also depends on other parameters (e.g., the rate of the charge or the mass transfer on the electrode double layer). The results of the photoelectrocatalytic experiments were compared to those of electrochemical (EC) and photocatalytic (PC) degradation of SMT. A significant enhancement was recorded in the case of the PEC degradation, leading at +1.5 V to an increase of the apparent rate constants of degradation, k, and mineralization, kTOC, of 153 and 298%, respectively, compared to the simple photocatalytic process.

The effects of carbon nitrogen ratio and salinity on the treatment of swine digestion effluent simultaneously producing bioenergy by microalgae biofilm

In order to remove high concentrations of ammonia nitrogen (NH4+-N) and refractory sulfamethazine (SM2) from swine digestion effluent, different carbon/nitrogen (C/N) ratios and salinity were used to determine the effects of pollutants removal in the microalgae biofilm system. Microalgae biofilm treatment under optimal environmental conditions in synthetic swine digestion effluent were C/N ratio of 20 and salinity of 140 mM. In order to make the actual swine digestion effluent discharge up to the standard, three different two-cycle treatments (suspended microalgae, microalgae biofilm, microalgae biofilm under the optimal conditions) were studied. The results showed that after two-cycle treatment with microalgae biofilm under the optimal conditions, the actual swine digestion effluent levels of total nitrogen (TN), NH4+-N, total phosphorus (TP), chemical oxygen demand (COD), SM2 were 22.65, 9.32, 4.11, 367.28, and 0.99 mg L−1, respectively, which could satisfy the discharge standards for livestock and poultry wastewater in China. At the same time, first-order kinetic simulation equations suggested a degradation half-life of 4.85 d for SM2 under optimal conditions in microalgae biofilm, and microbial community analysis indicated that the dominant genus was Halomonas. Furthermore, 35.66% of lipid, 32.56% of protein and 18.44% of polysaccharides were harvested after two-cycle in microalgae biofilm treatment under optimal environmental conditions. These results indicated that the regulation of C/N and salinity in microalgae biofilm for the treatment of swine digestion effluent was a high-efficiency strategy to simultaneously achieve wastewater treatment and bioenergy production.

Effect of subtherapeutic and therapeutic sulfamethazine concentrations on transcribed genes and translated proteins involved in Microbacterium sp. C448 resistance and degradation.

Microbacterium sp. C448, isolated from a soil regularly exposed to sulfamethazine (SMZ), can use various sulphonamide antibiotics as the sole carbon source for growth. The basis for the regulation of genes encoding the sulphonamide metabolism pathway, the dihydropteroate synthase sulphonamide target (folP), and the sulphonamide resistance (sul1) genes is unknown in this organism. In the present study, the response of the transcriptome and proteome of Microbacterium sp. C448 following exposure to subtherapeutic (33 µM) or therapeutic (832 µM) SMZ concentrations was evaluated. Therapeutic concentration induced the highest sad expression and Sad production, consistent with the activity of SMZ degradation observed in cellulo. Following complete SMZ degradation, Sad production tended to return to the basal level observed prior to SMZ exposure. Transcriptomic and proteomic kinetics were concomitant for the resistance genes and proteins. The abundance of Sul1 protein, 100-fold more abundant than FolP protein, did not change in response to SMZ exposure. Moreover, non-targeted analyses highlighted the increase of a deaminase RidA and a putative sulphate exporter expression and production. These two novel factors involved in the 4-aminophenol metabolite degradation and the export of sulphate residues formed during SMZ degradation, respectively, provided new insights into the Microbacterium sp. C448 SMZ detoxification process.

Surface-enhanced Raman scattering based determination on sulfamethazine using molecularly imprinted polymers decorated with silver nanoparticles.

Molecularly imprinted polymers (MIPs) were combined with surface-enhanced Raman scattering (SERS) and AgNPs were prepared by in situ reduction within the MIP for selective and sensitive detection of sulfamethazine (SMZ). The MIP@AgNPs composites were characterized in detail by several analytical techniques, showing the generation of polymers and the formation of AgNPs hot spots. The specific affinity and rapid adsorption equilibrium rates of MIP@AgNPs composites were verified by static and kinetic adsorptionstudies. The MIP@AgNPs with high selectivity and excellent sensitivity were used as SERS substrates to detect SMZ. A good linear correlation (R2 = 0.996) in rang of 10-10-10-6mol L-1 was observed between the Raman signal (1596cm-1) and the concentration of SMZ. Thelimit of detection (LOD) was as low as 8.10 × 10-11mol L-1 with relative standard deviations (RSD) of 6.32%. Thegood stability and reproducibility are also fully reflected in the SERS detection based on MIP@AgNPs. The method was successfully applied to the analysis of lake water samples, with recoveries in the range 85.1% to 102.5%. In summary, SERS detection based on MIP@AgNPs can be developed for a wider and broader range of practical applications. Schematic illustration of MIP@AgNPs sensor for the SERS detection of sulfamethazine.

Ti3+ self-doped and nitrogen-annealed TiO2 nanocone arrays photoanode for efficient visible-LED-light-driven photoelectrocatalytic degradation of sulfamethazine

Developing efficient, durable and visible-light-driven photoanode with excellent environmental adaptability is of great significance for photoelectrocatalytic (PEC) degradation of organic pollutants. In this work, a novel Ti3+ self-doped and nitrogen-annealed TiO2 nanocone arrays (Ti3+-TiO2NCs(N2)) photoanode was prepared for efficiently photoelectrocatalytic degradation of sulfamethazine (SMT) under visible light emitting diode (LED) irradiation, which obtained 98.68% removal for initial SMT concentration of 10 mg/L within 60 min. The visible light harvesting and charge transfer of TiO2NCs were significantly improved after nitrogen annealing treatment. Additionally, the introduction of moderate Ti3+ sites further lowered charge transport resistance and introduced a new impurity energy level, which efficiently accelerated the transmission of photogenerated carriers and then generated more h+ and active species to degrade pollutants. After 15 recycling degradation experiments, Ti3+-TiO2NCs(N2) still obtained more than 97% SMT removal, demonstrating highly durable. Also, it exhibited promising application prospect for treatment of real wastewaters (secondary effluent, pharmaceutical wastewater and mariculture wastewater).

Green valorization of end-of-life toner powder to iron oxide-nanographene nanohybrid as a recyclable persulfate activator for degrading emerging micropollutants

The sustainable management of toner waste (T–raw) was performed via carbonization at 500 °C (T-500) and 600 °C (T–600) to produce iron oxide-nanographene nanohybrid (FeO-NG) for activating persulfate (PS) to efficiently degrade dyes (methylene blue, MB), antibiotics (sulfamethazine, SMZ), and pesticides (diazinon, DZN). Morphology, crystallinity, chemical structure, chemical composition, surface area, and pore size distribution of the synthesized materials were investigated using various analyses. High degradation ratios of MB were attained over a wide pH range (2–7), and the optimum operating conditions were determined. The FeO-NG/PS system was tested in different water matrices. MB degradation efficiency dropped from 80.13% to 78.56% after five succeeding experiments, proving the high stability of T–500. Trapping experiments proved the major role of sulfate radicals and the minor contribution of singlet oxygen. The toxicity evaluation of the treated and untreated MB solutions was conducted via measuring the cell viability, showing an increase in cell viability ratio after the degradation of MB. The degradation efficiencies of DZN and SMZ were 97.54% and 83.7%, respectively and the mineralization ratios were 74.08% and 60.37% at initial concentrations of sulfamethazine and diazinon of 50 and 100 mg/L, respectively. The high degradation efficiency of emerging micropollutants as well as the inexpensiveness, and facile synthesis of the catalyst boost the prospect of applying the proposed system on an industrial scale.

Efficient Bias-Free Degradation of Sulfamethazine by TiO2 Nanoneedle Arrays Photoanode and Co3O4 Photocathode System under LED-Light Irradiation

Solving high electrical-energy input for pollutants degradation is one of the core requirements for the practical application of photoelectrocatalytic (PEC) technology. Herein, we developed a self-driven dual-photoelectrode PEC system (TiO2 NNs-Co3O4) composed of a TiO2 nanoneedle arrays (TiO2 NNs) photoanode and Co3O4 photocathode for the first time. Under light-emitting-diode (LED) illumination, the bias-free TiO2 NNs-Co3O4 PEC system exhibited excellent PEC performance, with an internal bias as high as 0.19 V, achieving near complete degradation (99.62%) of sulfamethazine (SMT) with a pseudo-first-order rate constant of 0.042 min−1. The influences of solution pH, typical inorganic anions, natural organic matter, and initial SMT concentration on the PEC performance were investigated. Moreover, the main reactive oxygen species (h+, •OH, •O2−) in the dual-photoelectrode PEC system for SMT decomposition were elaborated. The practical application feasibility for efficient water purification of this unbiased PEC system was evaluated. It was proved that the TiO2 NNs photoanode provided a negative bias while the Co3O4 photocathode provided a positive bias for the photoanode, which made this system operate without external bias. This work elucidated the cooperative mechanism of photoelectrodes, providing guidance to develop a sustainable, efficient, and energy-saving PEC system for wastewater treatment.