Ecological Structure Activity Relationships Research Articles

Quantitative and mechanistic elucidation of the reactive oxygen species for effective sulfamethoxazole removal in heterogeneous peroxymonosulfate activated by MOFs-derived cladding structure CoZn/NC@UiO

In cobalt-based catalyst/peroxymonosulfate (PMS) systems, the key issues are the leaching of metals and the stability of catalysts. In this study, a NH2-UiO-66 cladded CoZn/NC catalyst was synthesized for efficient degradation of sulfamethoxazole (SMX) using activated PMS. The removal efficiency of SMX could achieve 100% within 30 min. The leaching of Co2+ was inhibited to 0.05 ppm and the anti-interference and cyclic stability of the catalyst were enhanced by the NH2-UiO-66 shell. In addition, the quenching experiment, electron paramagnetic resonance (EPR) technique and probe experiment were used to analyze the reactive oxygen species (ROSs) qualitatively and quantitatively. The findings demonstrated that singlet oxygen (1O2) had the highest steady-state and cumulative concentration. However, 1O2 could only participate in the degradation of SMX through single electron transfer or addition reaction, resulting in a lower second-order rate constant of the SMX reaction with 1O2. Sulfate radical (SO4·-) contributed the most to the degradation of SMX due to the high reactivity of the sulfonamide structure in SMX to SO4·-. Finally, possible pathways for SMX degradation were proposed. The two primary mechanisms of SMX degradation were S-N cleavage and amino hydroxylation/oxidation. The toxicity of most of the intermediates was less than that of SMX through ecological structure–activity relationship analysis. Overall, a novel approach to synthesize low leaching and efficient cobalt based catalyst was put forward, and the activation mechanism of PMS was also revealed.

Deciphering the degradation of sulfonamides by UV/chlorination in aqueous solution: kinetics, reaction pathways, and toxicological evolution

UV/Cl is a cost-effective process and is often used in municipal water treatment plants as well as in industrial applications. UV/Cl method is found highly effective in degrading contaminants, including pathogens, The conventional methods for water treatment have been proven inefficient for the complete elimination of pollutants and generate harmful by-products in the environment. This study evaluated the efficacy of three different treatment methods, chlorination alone, UV photolysis, and UV/Cl, for the degradation of sulfonamides (SAs) in water. The results highlighted that UV/Cl treatment was an efficient method for enhancing the degradation of sulfisoxazole (SFX), sulfadimethoxine (SAT), and sulfaguanidine (SG), with substrates degrading in 5, 6.5, and 4 min. The study also investigated the reactive species generated in the UV/Cl system and found that ·OH was the species responsible for the elimination of SFX. Additionally, the study explored the intermediate products generated during the degradation of SFX under the UV/Cl system, identifying VI distinct degradation pathways. The presence of ·OH radicals significantly enhanced the degradation of SFX, while some chlorine species also contributed to the degradation. The study predicted the toxicity of degradation products from the UV/Cl system using the ECOSAR (Ecological Structure Activity Relationships) program and found that the final degradation products of SFX were non-toxic, but concerns were raised about acute toxicity.

A novel visible light-driven oxygen doped C3N4/Bi12O17Cl2/ferrate(VI) system for Bisphenol A degradation: Radical and nonradical pathways

In this study, visible light-activated photocatalyst oxygen-doped C3N4@Bi12O17Cl2 (OCN@BOC) and Fe(VI) coupling system was proposed for the efficient degradation of bisphenol A (BPA). The comprehensive characterization of the OCN@BOC photocatalyst revealed its excellent photogenerated carrier separation rate in heterogeneous structures. The OCN@BOC/Fe(VI)/Vis system exhibited a remarkable BPA removal efficiency of over 84% within 5 min. Comparatively, only 37% and 59% of BPA were degraded by single OCN@BOC and Fe(VI) in 5 min, respectively. Reactive species scavenging experiments, phenyl sulfoxide transformation experiments, and electron paramagnetic resonance experiments confirmed the involvement of superoxide radicals (⋅O2−), singlet oxygen (1O2), as well as iron(V)/iron(IV) (Fe(V)/Fe(IV)) species in the degradation process of BPA. Furthermore, density functional theoretical calculations and identification of intermediates provided insights into the potential degradation mechanism of BPA during these reactions. Additionally, simulation evaluations using an ecological structure activity relationship model demonstrated that the toxicity of BPA to the ecological environment was mitigated during its degradation process. This study presented a novel strategy for removing BPA utilizing visible light photocatalysts, highlighting promising applications for practical water environment remediation with the OCN@BOC/Fe(VI)/Vis system.

Assessing ecotoxicity, removal efficiency, and molecular response of freshwater microalgae to bisphenol AP

Bisphenol AP (BPAP), an analog of BPA and endocrine disrupter, is increasingly being detected in water, signaling its rise as an environmental contaminant similar to BPA, which is known for its health implications. This study investigated the ecotoxicity of BPAP in four freshwater microalgae (Chlorella sorokiniana, Chlamydomonas mexicana, Scenedesmus obliquus, and Chlorella vulgaris), along with their removal potential and biotransformation. This was followed by de novo transcriptomic analysis to elucidate the molecular response after BPAP exposure. The toxicity (120 h-EC50) of BPAP for microalgal species ranged from 1.509 mg L−1 to 6.509 mg L−1. C. mexicana exhibited the highest removal efficiency of 86.5 % after 12 days, followed by C. vulgaris (86.0 %), S. obliquus (78.9 %), and C. Sorokiniana (56.5 %) at 1 mg L−1. Eight biotransformed BPAP products were analyzed, and their toxicity was predicted to be lower than that of BPAP using the Ecological Structure Activity Relationships software. Transcriptomic analysis of C. mexicana revealed the differential expression of 4611 genes in processes related to metabolism, cellular activities, and stress responses. Genes encoding methyltransferases, glycosyltransferases, and various oxidoreductases, including electron-transferring flavoprotein dehydrogenase and glutaredoxin, were significantly upregulated in algal cells exposed to BPAP, suggesting the potential of C. mexicana for BPAP detoxification via glycosylation and transmethylation. These results offer novel insights into the ecotoxicity, removal potential, and biotransformation of BPAP in freshwater microalgae, with transcriptomic analysis, elucidating the molecular mechanisms of BPAP detoxification for effective environmental remediation.

Degradation of Isotianil in Water and Soil: Kinetics, Degradation Pathways, Mechanisms, and Ecotoxicity Assessments.

Pesticides are transported and transformed in soil and can enter surface water through various pathways. They undergo hydrolysis, oxidation, and photoconversion in surface water. Isotianil is a new fungicide that effectively controls rice blast. However, there are limited reports on its degradation. Herein, the hydrolysis and photolysis of isotianil in water and its degradation in soil samples from five provinces of China were investigated. The degradation products of isotianil were identified using ultrahigh-performance liquid chromatography-Q exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry, and four compounds were discovered for the first time. The degradation pathways of isotianil were inferred, and the reaction active site and degradation mechanism of isotianil were clarified based on density functional theory calculations. The ecotoxicity of the degradation product M118 (aminobenzonitrile) was found to be moderate toward Daphnia magna, which was predicted and confirmed by Ecological Structure Activity Relationships and the experiment, respectively. The results of this study will contribute to a better understanding of the fate of isotianil in the environment.

Percarbonate mediated advanced oxidation of irbesartan: A suitable alternative to chlorination?

This study aims to investigate the environmental fate of irbesartan when subjected to activated percarbonate treatment. The investigation delves into the formation of disinfection byproducts (DBPs) and evaluates their toxicity, and it seeks to draw comparisons with outcomes from treatment with sodium hypochlorite, already characterized in previous findings. The proposed treatment indicates the formation of at least 11 DBPs - eight identified for the first time - which have been isolated by various chromatographic techniques, identified by Nuclear Magnetic Resonance and Mass Spectrometry studies and for which a mechanism has been proposed to elucidate their formation. To evaluate irbesartan's biological impact during treatment with sodium percarbonate (SPC), a toxicity study of the DBPs was conducted using Daphnia magna, Aliivibrio fischeri, and Raphidocelis subcapitata, three model organisms. The ecotoxicity was evaluated using the Ecological Structure-Activity Relationships (ECOSAR) computer program and compared with experimental results. Compared to chlorination treatment, a lower mineralization percentage (−43 %) and amount of DBPs at least twice higher were observed. Toxicity assessment highlighted that DBPs formed during SPC treatment were more toxic than those from chlorination. ECOSAR predicted toxicity aligned with experimental findings. Additionally, the DBPs exhibited varying levels of toxicity, primarily attributable to the presence of aromatic and hydroxyl groups in their chemical structure, indicating that SPC treatment is not suitable for treatment of irbesartan polluted waters.

BiVO4-Driven photocatalytic degradation of pharmaceutical in Slurry Bubble Column Reactor: Influencing factors and toxicological profiling

As the pursuit for sustainable and effective solutions to address environmental pollution intensifies, a comprehensive approach in photocatalysis has become a subject of increasing interest. In this study, BiVO4 photocatalyst synthesized through a pH-controlled hydrothermal method was used for the degradation of tetracycline (TET), a prevalent pharmaceutical pollutant. Optimal conditions, particularly a pH of 9 and enriched dissolved oxygen (DO), significantly improve TET removal, achieving a 96 % degradation efficiency with a rate constant of k = 0.1069 min−1. The investigation revealed that the degradation predominantly involves the generation of reactive oxygen species (ROS), notably O2•−, which play a crucial role in the degradation of TET. Using the “ecological structure–activity relationships” (ECOSAR) program, the toxicity of the intermediates was assessed, highlighting the environmental implications of the photocatalytic process. In addressing the scalability for industrial applications, a Slurry Bubble Column Reactor (SBCR) was employed, and separation-stability tests of the photocatalyst were conducted. These tests confirmed the photocatalyst’s long-term effectiveness and stability, underscoring its potential for repeated use in large-scale applications. This comprehensive research not only underscores the potential of BiVO4 in removing environmental contaminants but also provides vital insights into ecological safety.

Effects of ball milling on hydrochar for integrated adsorption and photocatalysis performance

In this study, hydrochar (HC) was firstly treated by ball milling for methylene blue (MB) removal through combined adsorption-photodegradation. The ball-milled bamboo hydrochar (BM-HC) exhibited a maximum adsorption capacity of 49.522 mg/g and a synergistic adsorption-photodegradation removal rate of 95.22% within 30 min, which was superior to those of pristine HC (20.530 mg/g, 79.47%). Compared with HC, BM-HC had smaller particle size, increased quantities of polyfuran rings, enhanced adsorption of visible light, which were favorable for the enhancement of adsorption capacity and photodegradation rate. The effect of the catalyst dosage, MB concentration, water matrix, pH, coexisting ions on MB photodegradation were examined. The possible synergistic adsorption and photodegradation mechanism of MB was illustrated. The foremost active specie in the synergistic removal of MB was h+. In addition, the possible degradation pathways of MB were proposed depending on the intermediates detected by Liquid chromatography-mass spectrometry (LC-MS), and the biotoxicity of MB and its intermediates was evaluated by Ecological Structure-Activity Relationship (ECOSAR) program. This work confirms that ball-milled hydrochar could be used as a potential catalyst for pollutants removal in water via synergistic adsorption and photocatalysis.

Elucidating the photodegradation mechanism of octylisothiazolinone and dichlorooctylisothiazolinone in surface water: An in-depth comprehensive analysis

Octylisothiazolinone (OIT) and Dichlorooctylisothiazolinone (DCOIT), widely used antibacterial agents in coatings, have seen a sharp increase in use in response to the Coronavirus disease 2019 (Covid-19) pandemic, ultimately leading to their increase in the aquatic environment. However, their photodegradation process in surface water is still unclear. The purpose of this study is to investigate the photodegradation kinetics and mechanisms of OIT and DCOIT in natural water environments. Under simulated solar irradiation, they undergo direct photolysis in both natural freshwater and seawater mainly via their excited singlet states, while no self-sensitization photolysis was observed. The direct photolysis rate constants of OIT and DCOIT were 1.19 ± 0.07 and 0.57 ± 0.03 h−1, respectively. In addition, dissolved organic matter (DOM), NO3− and Cl− in natural waters did not contribute significantly to the photodegradation, and the light screening effect of DOM was identified as the main inhibiting factor. The photodegradation half-life of OIT was estimated to be 0.66 to 1.69 days, while the half-life of DCOIT was as high as 20.9 days during winter in surface water at 30°N latitude. Ring opening of the N-S bond and covalent bond breaking between CN are the main pathways for the photodegradation of OIT and DCOIT, which is verified by density-functional theory calculations. Ecological Structure Activity Relationships (ECOSAR) results indicate that OIT and DCOIT have “Very Toxic” biological toxicity, and the acute toxicity of their products is significantly reduced. It is noteworthy that the toxicity of the products of DCOIT is generally higher than that of OIT, and the chronic toxicity of most of the products is still above the “Toxic” level. Therefore, an in-depth understanding of the photodegradation mechanisms of OIT and DCOIT in aqueous environments is crucial for accurately assessing their ecological risks in natural water environments.

Insights into the photodegradation of decamethylammonium bromide (DDAB) under UV/H2O2 system: Photodegradation kinetic modeling, degradation mechanism and toxicity evaluation

Decamethonium bromide (DDAB), as a class of quaternary ammonium-based disinfectants (QACs), was widely used during the COVID-19 outbreak. The abuse of DDAB is harmful to the health of aquatic organisms. The UV/H2O2 process is popularly utilized for the removal of trace contaminants from aqueous environments. Thus, in this paper, DDAB was selected as the model of QACs, and the degradation kinetics were simulated by Kintecus software. It was indicated that the effect of the degradation efficiency of DDAB was dominated by [·OH]ss. The degradation efficiency of DDAB was greater than 95 % when [·OH]ss was higher than 1.04×10−12 M. The high dosages of H2O2 (>100 μM) and the less concentration of pollutants (<10 μM) were more beneficial to the degradation of DDAB. The high dosages of NOM and CO32- in the system scavenged ·OH and thereby inhibited the degradation of DDAB. The interference of Cl- on the degradation efficiency was negligible. Additionally, the optimal pH value for removing DDAB was between 4 and 7. Besides, the degradation pathway of DDAB was inferred by Density Functional Theory (DFT) and Ultra-high Performance Liquid Chromatography-tandem Mass Spectrometry (UPLC-MS/MS). The results showed that the degradation of DDAB began with C-N bond breaking, then generated aldehydes, underwent demethylation reaction, and finally converted to low molecule weight molecules. The results of Ecological Structure Activity Relationships (ECOSAR) toxicity assessment demonstrated that the toxicity of all the degradation products was significantly low. Overall, this study provides theoretical basis for the removal of QACs in the aqueous environment.

Laser-induced growth of metal oxide films on quartz tubes for photocatalytic water treatments

A solid-state pulsed laser technique was developed to in situ grow arbitrary immobilized catalysts (Fe3O4, CeO2, WO3 etc.) on the inner surface of quartz tube with robust adhering strength. In a case study, anatase/rutile hetero-phase TiO2 film was deposited to serve as immobilized photocatalysts for the effective removal of antibiotics from aqueous environment. The X-ray absorption spectroscopy, low temperature electron paramagnetic resonance and the density functional theory simulation directly confirm a defect-assisted type-II band alignment was established to facilitate the charge transfer at the hereto-interphase. In addition, the oxygen vacancy enriched anatase phase with greater binding energy towards the dissolved oxygen facilitated the O2– generation. Meanwhile, the rutile phase enriched with Ti3+ could effectively activate the antibiotics to promote the direct h+ mediated oxidation. Such integration of unique atomic vacancies prevent defects from becoming electron-hole recombination centers and consequently extend the lifetime of the photoexcited charge carrier. The degradation mechanism of oxytetracycline was thoroughly examined by ultra-high resolution electrospray time-of-flight mass spectrometry and Fukui function, while the ecological structure–activity relationships program assessed the toxicity of contaminant to the environment. Milewhile, a continuous water treatment apparatus employing the catalytic tubes as reactors was established and demonstrated a ∼ 95 % OTC degradation under the natural sunlight adopting river water as the background. The experimental studies also claimed that ∼ 90 % of the initial activity could be retained after 100 cycles reuse, which permits their great potential for the applicational scenarios.

Cd2+ enhancing the bromination of bisphenol A in Brassica chinensis L.: Pathways and mechanisms

Traditional heavy metal pollution, such as cadmium, impacts the transformation and risks of bisphenol pollutants (like bisphenol A, BPA), in plants, especially due to the ubiquitous presence of bromide ion. Although it has been discovered that the bromination of phenolic pollutants occurs in plants, thereby increasing the associated risks, the influence and mechanisms of bromination under complex contamination conditions involving both heavy metals and phenolic compounds remain poorly understood. This study addresses the issue by exposing Brassica chinensis L. to cadmium ion (Cd2+, 25–100 μM), with the hydroponic solution containing BPA (15 mg/L) and bromide ion (0.5 mM) in this work. It was observed that Cd2+ primarily enhanced the bromination of BPA by elevating the levels of reactive oxygen species (ROS) and the activity of peroxidase (POD) in Brassica chinensis L. The variety of bromination products within Brassica chinensis L. increased as the concentration of Cd2+ rose from 25 to 100 μM. The substitution positions of bromine were determined using Gaussian calculations and mass spectrometry analysis. The toxicity of bromination products derived from BPA was observed to increase based on Ecological Structure-Activity Relationships analysis and HepG2 cytotoxicity assays. This study provides new insights into the risks and health hazards associated with cadmium pollution, particularly its role in enhancing the bromination of bisphenol pollutants in plants.

Novel indazolylchromones: synthesis, fungicidal evaluation, molecular docking and aquatic toxicity prediction.

Fungal diseases cause substantial loss to agricultural crops, affecting both quantities and quality. Although several methods are used for preventing disease incidence, fungicides remain crucial for higher yields and better quality. But in the past, the efficacy of several fungicides has decreased due to increased cases of fungicide resistant. In our pursuit of new effective fungicides, we synthesised a series of twenty 2-Indazol-1-yl-chromen-4-one derivatives (6a- 6t). The characterization of synthesized compounds was performed by several spectroscopic methods including Infrared, Nuclear Magnetic Resonance (1H and 13C) and HRMS. Out of 20 synthesised compounds, 19 (6b- 6t) were found to be novel. All synthesised indazolylchromones showed very good antifungal activity against Sclerotium rolfsii and Fusarium oxysporum. Among the tested compounds, 6t and 6f exhibited very good fungicidal activity against S. rolfsii with an ED50 of 10.10mgL-1 and 16.18mgL-1, respectively. In case of Fusarium oxysporum compound 6f displayed good' activity with an ED50 value of 27.82mgL-1. Molecular docking study was done to predict the binding sites of most active compounds, 6t and 6f with Cytochrome P450 14alpha -sterol demethylase (CYP51) enzyme using molsoft software. The acute toxicity predictions the of synthesized compounds for fish (LC50,96 Hr), daphnid (LC50, 48 Hr) and green algae (EC50, 96Hr) and the chronic toxicity predictions (ChV) were assessed using Ecological Structure Activity Relationship (ECOSAR) model. As per ECOSAR prediction, all the chemicals are inside AD and not missing predictions.

Construction of novel S-defects rich ZnCdS nanoparticles for synergistic visible light assisted photocatalytic degradation of rhodamine B: Insights into mechanism, pathway and by-products toxicity evaluation

The contamination of wastewater by azo dyes indicates serious environmental risks. Currently, industries worldwide use approximately 700,000 tons of these dyes annually, making their removal a significant challenge. In photocatalysis research, a prominent area of dedication to the advancement of visible light photocatalysis aims to achieve superior performance in overall activity. In this study, we fabricated ZnCdS nanoparticles (NPs) via a simple co-precipitation strategy, and sulphur (S)-defect-rich ZnCdS NPs (D-ZnCdS) were created through the ball milling method. These S-defect nanoparticle (NPs) catalysts were utilized for rhodamine B (RhB) dye photocatalytic degradation experiment. (XRD) X-ray diffractometer, X-ray photoelectron spectroscopy (XPS), surface-enhanced Raman spectroscopy, and photoluminescence (PL) spectroscopy characterization studies explained the induced S-defect rich in D-ZnCdS NPs. Further, the morphological, band gap determination, and photogenerated charge carrier recombination efficiency were studied using different analytical and spectroscopic characterization techniques. The Brunauer-emmett-teller (BET) results indicate the increased surface area of D-ZnCdS NPs thereby providing more active sites. The photocatalytic degrading efficiency of D-ZnCdS over RhB explains the complete degradation of pollutants within 260 min. This enhancement in the catalytic process is attributed to the increased absorption of photon energy from the visible light and large defect-rich active sites. Further, the involvement of hydroxyl (*OH) and superoxide radicals (O2*-) in the degradation of RhB along with the presence of sulphur defects, significantly improves the charge transfer in ZnCdS NPs. The involvement of certain factors like pH, ions, NCs catalyst and different RhB concentrations on RhB degradation was investigated. Additionally, D-ZnCdS NPs showed stable degrading capability even after six consecutive cycles of catalytic RhB degradation. The by products formed during the RhB photodegradation experiment were identified using Gas chromatography-mass spectrometer (GC-MS) analysis, and toxicity in fish, daphnia, and algae was examined using the Ecological structure-activity relationships (ECOSAR) program. From the above findings, the current research work provides a new strategy for utilizing defect-engineered D-ZnCdS NPs as a promising catalyst for various environmental remediation applications and paves a ways for manufacturing innovation.

Robust advantage of MXene/g-C3N4 loaded on Fe2WO6/BiIO4 nano-platform for chemo-peroxidase colorimetric detection of uranyl ions, antifungal properties, photocatalytic degradation of p-chlorophenol, and eco-toxicity studies

In this study, we have designed a nanocomposites based on MXene/g-C3N4 (MX/CN) loaded on Fe2WO6/BiIO4 (FWO/BIO) for different applications. The nanocomposites were identified by using the structural and morphological studies including XRD, FESEM, EDS, DLS, TGA, BET, UV–vis, XPS techniques. The average sizes of BIO, FWO/BIO, and MX/CN/FWO/BIO were 44, 46, and 58 nm, respectively. The synthesized MX/CN/FWO/BIO nanocomposites was utilized for the peroxidase colorimetric identification of uranyl ions (UO22+) with the excellent selectivity and sensitivity properties (LOD: 3.21 nM). The antifungal efficiency of the as-fabricated nanomaterials was investigated and the inhibition zone at high concentration 2.5 mg/mL of MX/CN/FWO/BIO nanocomposites were 19.74, 17.91, 24.25, and 21.32 mm against Aspergillus spp., Penicillum spp., Candida spp. and Fusarium spp., respectively. The MX/CN/FWO/BIO nanocomposites was utilized in photocatalysis process for decomposition of p-chlorophenol under visible light lamp. The findings showed that the MX/CN/FWO/BIO nanocomposites can be degrade p-chlorophenol (100.0 %) under visible light irradiation (80 min). The photocatalytic response was decreased about 2 % after 5th cycle times, and showed the best stability of the MX/CN/FWO/BIO nanocomposites. The quenching test shows the mechanism of p-chlorophenol degradation was conducted by •O2−, and •OH species. Additionally, the ecological structure activity relationships ECOSAR software was utilized to evaluate the toxicity of the p-chlorophenol and the intermediates produced. This work can lead for manufacturing innovation in near future.

Periodate activation by MnFe2O4 spinel for sulfamethoxazole degradation: Iodate radical dominance, degradation pathway, DFT calculation and toxicity assessment

This study synthesized spinel MnFe2O4 at different temperatures, which was applied to activate periodate (PI) for sulfamethoxazole (SMX) degradation. It was found that the 500-MFO (MnFe2O4 calcined at 500 ℃) demonstrated superior activity in PI activation, with notable sustainability but strong substrate selectivity. Furthermore, a comprehensive analysis, including quenching experiment, electron paramagnetic resonance (EPR) technique, X-ray photoelectron spectroscopy (XPS) analysis, metal ions leaching detection, homogeneous PI activation, and methyl phenyl sulfoxide (PMSO) probe test, revealed that homo- and heterogeneous pathways as well as free and non-free radical routes coexisted in the 500-MFO/PI system. Multiple active species, including iodate radical (IO3•), hydroxyl radical (•OH), superoxide radical (O2•-), singlet oxygen (1O2), and Mn(IV) were identified, with IO3• from heterogeneous activation being the primary species. When PMSO and SMX coexisted, PMSO could react with Mn(IV), promoting the regeneration of Mn reaction sites and the production of IO3•, thereby being beneficial for the degradation of SMX. The degradation pathways of SMX were elucidated through high-performance liquid chromatography-mass spectrometry (HPLC-MS) and density functional theory (DFT) calculation. The acute and chronic toxicity of thirteen by-products to aquatic organisms were predicted using the Ecological Structure Activity Relationships (ECOSAR) software, with the corresponding results revealing that although the toxicity of intermediates fluctuated, the final products were environmentally benign. Therefore, this investigation provides a viable method for SMX degradation in wastewater treatment.

Enhanced peroxymonosulfate activation for degradation of iodinated contrast media by microwave-induced bimetallic carbon-based catalysts: Insight into the synergistic mechanism between microwaves and bimetallic sites

Microwave-assisted catalytic oxidation process was a promising wastewater treatment technology for the disposal of refractory organic contaminants. Nevertheless, its practical implementation was limited by the high energy consumption of microwaves and the poor sustainable reactivity of catalysts. To address these issues, the microwave-assisted dielectric-activation double-responsive Co/Fe carbon-based catalyst (CoFe/NC-3) was used to activate peroxymonosulfate (PMS) for oxidative degradation of refractory diatrizoate (DTZ). The results showed that the DTZ was completely degraded within 6 min in the MW/CoFe/NC-3/PMS reaction system, and the degradation efficiency increased by 82.38% compared with the MW/Fe/NC/PMS system. It was attributed to the enriched active sites and prolonged redox cycling capability of the bimetallic catalysts. Moreover, microwave enhanced electron migration ability to accelerate the circulation of Fe3+/Fe2+/Fe0 and Co3+/Co2+ and generate more reactive oxygen species (ROSs) for the high-efficiency degradation of DTZ. The degradation pathways of DTZ were elucidated by LC-MS in combination with DFT calculation and the product toxicity was evaluated using ecological structure-activity relationship software (ECOSAR). The results showed that the majority of intermediate degradation products were not acute or chronic toxicity to fish, daphnia, and green algae. Overall, these results revealed that the MW/CoFe/NC-3/PMS system was a cost-effective and stable method for wastewater treatment.

Myricetin Inhibits Photodegradation of Profenofos in Water: Pathways and Mechanisms

Profenofos is a detectable insecticide in the environment with strong toxicity to non-targeted organisms. Photodegradation is a main transformation of profenofos in the environment. Myricetin is a flavonoid that strongly scavenges free radicals. The effect of myricetin on the photodegradation of profenofos was studied. The half-lives (T1/2) of profenofos were 1.7–7.0 and 90 h under artificial light and sunlight. The photolysis rate of profenofos decreased by 1.87–4.72 and 7.62 times with the addition of 20 ratios of myricetin. Free radicals reacting with profenofos were •OH and 1O2, and the key free radical was •OH. Myricetin strongly scavenged •OH and 1O2 which rapidly reacted with profenofos. O-(2-Chlorophenyl)-O-ethyl-S-propyl phosphorothioate (M3) and O-(2-chlorophenyl)-O-ethyl phosphorothioate (M4) were major and new photoproducts of profenofos. According to the Ecological Structure Activity Relationships, photodegradation of profenofos was a detoxification process, but myricetin inhibited the photodegradation of profenofos and its photoproducts. These results highlight the implication of myricetin on the fate and potential risk of profenofos in the environment.

Green synthesis of Mn2O3 activated PDS to degrade estriol in medical wastewater and its degradation pathway

While green synthesized Mn2O3 has been used to activate peroxydisulfate (PDS) to degrade estrogens, effective application in real wastewater is less common due to variation in environmental matrices in wastewater. Here, green synthesized Mn2O3 was used as a Fenton-like catalyst to activate PDS for estriol (E3) degradation in wastewater. The results show that the high concentration of K+ and humic acid in wastewater could inhibit the activation process of the Mn2O3/PDS system, resulting in low removal efficiency of E3 in wastewater. However, when the concentration of PDS was increased to 15 mM, the removal efficiency of E3 in medical wastewater can reach 100 %, because the high PDS concentration increases the main reactive oxygen species singlet oxygen (1O2) in medical wastewater. XRD and SEM-EDS analysis indicate that the crystal structure of Mn2O3 is stable, with a consistent rice grain-like morphology before and after reaction. XPS results show no obvious changes in the percentages of Mn(II), Mn(III) and Mn(IV) before and after reaction, indicating that Mn2O3 has good stability when degrading E3 in medical wastewater. Based on density functional theory (DFT) calculations, liquid chromatography-mass spectrometry (LC-MS), and ecological structure–activity relationship (ECOSAR) modeling data analysis, the reactive oxygen species produced by the Mn2O3/PDS system mainly attack the benzene ring structure of E3, where the toxicity of its intermediate products declines significantly after breaking the benzene ring structure. Overall, this work provides greater understanding of the E3 degradation pathway and the toxicity of its degradation products.

Predicting environmental risks of pharmaceutical residues by wastewater surveillance: An analysis based on pharmaceutical sales and their excretion data

Pharmaceutical residues are increasingly becoming a significant source of environmental water pollution and ecological risk. This study, leveraging official national pharmaceutical sales statistics, predicts the environmental concentrations of 33 typical pharmaceuticals in the Tianjin area. The results show that 52 % of the drugs have a PEC/MEC (Predicted Environmental Concentration/Measured Environmental Concentration) ratio within the acceptable range of 0.5–2, including atenolol (1.21), carbamazepine (1.22), and sulfamethoxazole (0.91). Among the selected drugs, tetracycline, ciprofloxacin, and acetaminophen had the highest predicted concentrations. The EPI (Estimation Programs Interface) biodegradation model, a tool from the US Environmental Protection Agency, is used to predict the removal efficiency of compounds in wastewater treatment plants. The results indicate that the EPI predictions are acceptable for macrolide antibiotics and β-blockers, with removal rates of roxithromycin, spiramycin, acetaminophen, and carbamazepine being 14.1 %, 61.2 %, 75.1 %, and 44.5 %, respectively. However, the model proved to be less effective for fluoroquinolone antibiotics. The ECOSAR (Ecological Structure-Activity Relationships) model was used to supplement the assessment of the potential impacts of drugs on aquatic ecosystems, further refining the analysis of pharmaceutical environmental risks. By combining the concentration and detection frequency of pharmaceutical wastewater, this study identified 9 drugs with significant toxicological risks and marked another 24 drugs as substances of potential concern. Additionally, this study provides data support for addressing pharmaceutical residues of priority concern in subsequent research.