Environmental micro-molar H2O2 reduces the efficiency of glyphosate biodegradation in soil.

Glyphosate is one of the most widely used pesticides globally. The environmental micro-molar hydrogen peroxide (H2O2)-driven Fenton reaction has been reported to degrade herbicides in natural water. However, the impact of micro-molar H2O2 (50 µM) on the degradation of glyphosate in soil and glyphosate-degrading bacteria remains unclear. In this study, degradation of glyphosate in the sterilized and unsterilized soil system and MSM medium under micro-molar H2O2 was investigated; bacterial diversity, enzyme activity and gene abundance in the soil following micro-molar H2O2 addition were also investigated. The results indicated that the addition of micro-molar H2O2 facilitated the degradation of glyphosate in a sterilized environment, resulting in a 76.30% decrease in glyphosate within 30 days. The degradation of glyphosate increased by 52.32% compared to the control treatment. However, in an unsterilized environment, the addition of micro-molar H2O2 leads to a reduction in the biodegradation efficiency of glyphosate. Bacteria, enzymes and specific genes were found to be affected to varying degrees. Firstly, micro-molar H2O2 affects the relative abundance of functional bacteria related to glyphosate degradation, such as Afipia, Microcoleus and Pseudomonas. Secondly, micro-molar H2O2 resulted in a decrease in soil phosphatase activity. Thirdly, the expression of resistance genes was affected, particularly the glyphosate resistance gene aroA. The findings presented a novel research perspective on the degradation of soil glyphosate by micro-molar H2O2.

Occurrence and health risks of multiple emerging bisphenol S analogues in pregnant women from South China.

Recently, there has been increasing concern regarding the emergence of bisphenol S analogues (BPSs) due to their potential toxicity. However, their exposure levels and associated health risks in susceptible populations remain unknown. In our study, we analyzed bisphenol A (BPA), along with 11 common BPA analogues (BPAs), and nine emerging BPSs in urine samples collected from 381 pregnant women in South China. All nine BPSs were first detected in pregnant women's urine. In addition to BPA, two BPAs, three BPSs including Diphenylsulfone (DPS), Bis(phenylsulfonyl)phenol (DBSP) and Bis(3-allyl-4-hydroxyphenyl)sulfone (TGSA), were identified as the predominant bisphenols, with detection frequencies ranging from 53-100 %. BPA still exhibited the highest median concentration at 0.624 ng/mL, followed by DPS (0.169 ng/mL), BPS (0.063 ng/mL) and DBSP (0.023 ng/mL). Importantly, mothers with higher levels of BPA, DBSP, DPS, and TGSA in their urine are statistically more likely to give birth to premature infants with shorter lengths at birth or smaller head circumference (p < 0.05). Although the median exposure to 21 bisphenols did not exceed the tolerable daily intake (TDI) of BPA, it did surpass the recently proposed BPA TDI (0.2 ng/kg bw/day) by a factor ranging from 1.1-99 times. This study signifies the first report unveiling the prevalence of multiple bisphenols, particularly emerging BPSs, in the urine of pregnant women in South China.

Co-exposure of parabens, benzophenones, triclosan, and triclocarban in human urine from children and adults in South China.

Endocrine-disrupting chemicals (EDCs) are pervasive in the environment, prompting significant public concern regarding human exposure to these pollutants. In this study, we analyzed the levels of various endocrine-disrupting compounds, including parabens (PBs), benzophenones (BzPs), triclocarban (TCC) and triclosan (TCS), across 565 urine samples collected from residents of South China. All 11 target chemicals were detected at relatively high frequencies (41-100%), with the most prevalent ones being 3,4-dihydroxybenzoic acid (5.39 ng/mL), methyl-paraben (5.12 ng/mL), ethyl-paraben (3.11 ng/mL) and triclosan (0.978 ng/mL). PBs emerged as the most predominant group with a median concentration of 32.2 ng/mL, followed by TCs (sum of TCC and TCS, 0.998 ng/mL) and BzPs (0.211 ng/mL). Notably, urinary concentrations of PBs in adults were significantly higher (p < 0.01) compared to children, while BzPs and TCs were elevated in children (p < 0.001). The increased presence of BzPs and TCs in children is a cause for concern, given their heightened sensitivity and vulnerability to chemicals. Significant correlations were found between urinary target compounds and demographic factors, including gender, age and body mass index. Specifically, females, younger adults (18 ≤ age ≤ 35) and individuals with under/normal weight (16 ≤ BMI ≤ 23.9) were found to have higher exposure levels to EDCs, as indicated by the median values of their estimated daily intakes. Despite these higher levels still being lower than the acceptable daily intake thresholds, the health risks stemming from simultaneous exposure to these EDCs must not be overlooked.

Aged polystyrene microplastics exposure affects apoptosis via inducing mitochondrial dysfunction and oxidative stress in early life of zebrafish.

In recent years, the toxic effects of microplastics (MPs) on aquatic organisms have been increasingly recognized. However, the developmental toxicity and underlying mechanisms of photoaged MPs at environmental concentrations remain unclear. Therefore, the photodegradation of pristine polystyrene (P-PS) under UV irradiation was used to investigate, as well as the developmental toxicity and underlying mechanisms of zebrafish (Danio rerio) exposed to P-PS and aged polystyrene (A-PS) at environmentally relevant concentrations (0.1-100 µg/L). Mortality, heart rate, body length, and tail coiling frequency of zebrafish larvae were the developmental toxicity endpoints. A-PS had increased crystallinity, the introduction of new functional groups, and higher oxygen content after UV-photoaging. The toxicity results showed that exposure to A-PS resulted in more adverse developmental toxicity than exposure to P-PS. Exposure to A-PS induced oxidative damage, as evidenced by elevated production of reactive oxygen species (ROS) and DNA damage, and led to decreased mitochondrial membrane potential (MMP) and causes the release of cytochrome c (cyt c) from the mitochondria. The caspase-3/-9 activation signaling pathways may cause developmental toxicity via mitochondrial apoptosis. Significant changes in the expression of genes were further explored linking with oxidative stress, mitochondria dysfunctions and apoptosis pathways following A-PS exposure. These findings underscore the importance of addressing the environmental applications of aged MPs and call for further research to mitigate their potential risks on aquatic ecosystems and human health.

Neonicotinoid insecticides and metabolites levels in neonatal first urine from southern China: Exploring links to preterm birth.

Neonicotinoids (NEOs) have indeed become the most widely used insecticides worldwide. Concerns have been raised about their potential impact on newborns due to maternal exposure and their unique neurotoxic mode of action. However, it is still poorly understood whether in utero exposure of pregnant women to environmental NEOs and their metabolites can cause carryover effects on vulnerable newborns and subsequent health consequences. In this study, we determined the concentrations of 13 NEOs and their metabolites in the first urine collected from 92 newborns, both preterm and full-term, in southern China during 2020 and 2021. NEOs and their metabolites were identified in 91 urine samples, with over 93% of samples containing a cocktail of these compounds, confirming their maternal-fetal transfer. N-desmethyl-acetamiprid, imidaclothiz, clothianidin and flonicamid were the most commonly detected analytes, with detection frequencies of 59-87% and medians of 0.024-0.291 ng/mL in the urine. The relative abundance of imidaclothiz was significantly higher in preterm newborns, those with head circumferences below 33 cm, birth lengths less than 47 cm, and weights below 2500 g (p < 0.05). When comparing newborns in the 2nd quartile of imidaclothiz concentrations with those in the 1st quartile, we observed a significant increase in the odds of preterm outcomes in the unadjusted model (odds ratio = 3.24, 95% confidence interval = 1.02-10.3). These results suggest that exposure to elevated concentrations of imidaclothiz may be associated with preterm birth.

Biomonitoring of glyphosate and aminomethylphosphonic acid: Current insights and future perspectives.

Glyphosate is one of the most widely used herbicides globally, raising concerns about its potential impact on human health. Biomonitoring studies play a crucial role in assessing human exposure to glyphosate and providing valuable insights into its distribution and metabolism in the body. This review aims to summarize the current trends and future perspectives in biomonitoring of glyphosate and its major degradation product of aminomethylphosphonic acid (AMPA). A comprehensive literature search was conducted, focusing on studies published between January 2000 and December 2022. The findings demonstrated that glyphosate and AMPA have been reported in different human specimens with urine as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with liquid/gas chromatography-tandem mass spectrometry have achieved matrix elimination and accurate analysis. We also examined and compared the exposure characteristics of these compounds among different regions and various populations, with significantly higher levels of glyphosate and AMPA observed in Asian populations and among occupational groups. The median urinary concentration of glyphosate in children was 0.54 ng/mL, which was relatively higher than those in women (0.28 ng/mL) and adults (0.12 ng/mL). It is worth noting that children may exhibit increased susceptibility to glyphosate exposure or have different exposure patterns compared to women and adults. A number of important perspectives were proposed in order to further facilitate the understanding of health effects of glyphosate and AMPA, which include, but are not limited to, method standardization, combined exposure assessment, attention for vulnerable populations, long-term exposure effects and risk communication and public awareness.

A salting-out assisted liquid-liquid extraction method for 25 emerging pesticides in follicular fluid.

Emerging pesticides of neonicotinoids (NEOs) and "Universal Pesticides" (UPs) are a growing global concern due to their growing commercial importance and potential risks to human health. The currently available analytical methods for these pesticides in biomonitoring were usually tailored for limited number of analytes, or were time consuming and costly. In this study, an efficient and sensitive method for the analysis of 16 NEOs and nine UPs in human follicular fluid (FF) was developed by using a salting-out assisted liquid-liquid extraction (SALLE) method and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method performance was evaluated by calibration linearity (r > 0.99), sensitivity at limits of quantification (0.01-0.50 ng/mL), accuracy at relative recoveries (81-117%) and precision at relative standard deviations (≤16%). The developed method was further validated by analyzing 21 human FF samples that were collected from a hospital in Guangzhou, China. Among the 25 study analytes, two NEOs and six UPs had their detection rates over 85% and medians at 0.048-0.808 ng/mL in the FF samples. Considering the well-known toxicity of these pesticides and their metabolites, it is urgent to figure out exposure profiles of study pesticides and potential reproductive risk for women. To the best of our knowledge, this study is the first to develop and apply the SALLE method in the extraction of 16 NEOs and nine UPs simultaneously in human FF.

Neonicotinoid insecticides and their metabolites: Specimens tested, analytical methods and exposure characteristics in humans.

The use of neonicotinoid insecticides (NEOs) has been rising globally due to their broad-spectrum insecticidal activity, unique mode of neurotoxic action and presumed low mammalian toxicity. Given their growing ubiquity in the environment and neurological toxicity to non-target mammals, human exposure to NEOs is flourishing and now becomes a big issue. In the present work, we demonstrated that 20 NEOs and their metabolites have been reported in different human specimens with urine, blood and hair as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with high performance liquid chromatography-tandem mass spectrometry have successfully achieved matrix elimination and accurate analysis. We also discussed and compared exposure characteristics of these compounds among types of specimens and different regions. A number of important knowledge gaps were also identified in order to further facilitate the understanding of health effects of NEO insecticides, which include, but are not limited to, identification and use of neuro-related human biological samples for better elucidating neurotoxic action of NEO insecticides, adoption of advanced non-target screening analysis for a whole picture in human exposure, and expanding investigations to cover non-explored but NEO-used regions and vulnerable populations.

Occurrence of multiple bisphenol S analogues in children from Shantou, China.

Emerging bisphenol S analogues (BPSs) have gained their application perspectives to replace bisphenol A (BPA) and BPA analogues (BPAs). However, the extent of human exposure and potential health risk from BPSs is rarely known yet. We hypothesized that children living in Shantou, China, a well-known e-waste recycling city, may expose to emerging BPSs together with BPA and BPAs. In this study, BPA, six commonly used BPAs and 11 emerging BPSs were determined simultaneously in 240 urine samples collected from children residing in Shantou. BPA, BPS, bisphenol F, bisphenol AF and three BPSs of 2,4'-bis(hydroxyphenyl)sulfone, 4-((4-(allyloxy)phenyl)sulfonyl)phenol and diphenylsulfone (DPS) were the urinary predominant bisphenols with detection frequencies of 67-100% in the children. BPA was found at the highest median concentration (3.36 µg/g creatinine) followed by BPS (0.313) and DPS (0.187). It is interesting to find that the girls and children in the younger group (2 ≤ age < 5) had consistently higher concentrations of the seven dominant bisphenols than the boys and these of the older group (5 ≤ age ≤ 10), respectively. The children with under/overweight suffered higher burdens of bisphenol exposure based on medians of estimated daily intakes. Association analysis results indicated that the Shantou children exposed themselves to multiple BPSs along with BPA and BPAs from assumed consumer products and/or contaminated environments.

Neonicotinoids residues in cow milk and health risks to the Chinese general population.

The application of neonicotinoid insecticides (NEOs) has increased dramatically in the world since being introduced in 1990s, yet the extent of human exposure and potential health risk is not fully unraveled. In this study, the residues were analyzed of 16 NEOs and their metabolites in 205 commercial cow milk samples circulating in Chinese market. All the milk samples contained at least one quantified NEO, and over 90% of samples contained a cocktail of NEOs. Acetamiprid, N-desmethyl acetamiprid, thiamethoxam, clothianidin and imidaclothiz were the most commonly detected analytes with detection frequencies of 50-88% and medians of 0.011-0.038 ng/mL in milk. Geographical origin was an important factor to influence abundances and levels of NEOs contamination in milk. Chinese local milk bore a significant higher risk from NEOs contamination than the imported milk. In China, the northwest presented the greatest concentrations of the insecticides relative to the north or south. Organic farming, ultra heat treatment and skimming could significantly reduce levels of NEOs contamination in milk. A relative potency factor method was used to evaluate estimated daily intake of NEO insecticides, and found the children had 3.5-5 times higher exposed risk via milk ingestion than the adults. The high frequency of NEOs detection in milk offers us a snapshot of the ubiquity of NEOs in milk, with possible health implications especially for children.

Occurrence of emerging bisphenol S analogues in urine from five occupational populations in South China.

Bisphenol S (BPS) and its 11 emerging analogues were investigated in 325 urine samples from five occupational populations in South China. Besides BPS, ten emerging BPS analogues were newly identified and detected in the urine. It should be noted that urinary concentrations of dominant BPS analogues of 2,4'-bis(hydroxyphenyl)sulfone (2,4-BPS), bis(3-allyl-4-hydroxyphenyl)sulfone (TGSA) and diphenylsulfone (DPS) were 1.1-2.3 times higher than that of BPS, with overall detection frequencies at 74-91 %. The median sum concentrations of the target 12 bisphenols (ng/mL) were found highest in urine from cashiers (1.12), followed by water plant staffs (0.994), teachers (0.552), doctors (0.408) and power plant staffs (0.333). The composition profile of the urinary dominant bisphenols was occupational-dependent, with 2,4-BPS accounting for 45-73 % in cashiers and power plant staffs, and with DPS and TGSA for 74-82 % among doctors, teachers and water plant staffs. Significant correlations were found among the most frequently detected bisphenols in cashiers, indicating their common application and emission pathways. The median exposures based on estimated daily intakes (EDIs, ng/kg bw/day) for the 12 bisphenols in cashiers and water plant staffs (31.6-35.6) were 1.8-3.4 times higher than those of teachers, doctors and power plant staffs (10.6-17.5). This is the first study to identify multiple emerging BPS analogues in urine from occupational populations, especially cashiers and water plant staffs.

Molecular structure on the detoxification of fluorinated liquid crystal monomers with reactive oxidation species in the photocatalytic process.

Fluorinated liquid crystal monomers (LCMs) are begun to emerge as new persistent organic pollutants. Herein, the structure-reactivity relationships of fluorinated LCMs 1,2,3-trifluoro-5-[3-(3-propylcyclohexyl)cyclohexyl]benzene (TPrCB), 1,2-difluoro-4-[trans-4-(trans-4-propylcyclohexyl)cyclohexyl]benzene (DPrCB), 4-[(trans,trans)-4'-(3-Buten-1-yl)[1,1'-bicyclohexyl]-4-yl]-1,2-difluoro-benzene (BBDB) and 1-[4-(4-ethylcyclohexyl)cyclohexyl]-4(trifluoromethoxy)benzene (ECTB) subject to photocatalysis-generated oxidation species were investigated. The degradation rate constant of BBDB was 3.0, 2.6, and 6.8 times higher than DPrCB, TPrCB and ECTB, respectively. The results reveal that BBDB, DPrCB and TPrCB had mainly negative electrostatic potential (ESP) regions which were vulnerable to electrophilic attack by h+, •OH and •O2 -, while ECTB was composed of mainly positive ESP regions which were vulnerable to nucleophilic attack by •OH and •O2 -. The detoxification processes of BBDB, DPrCB and TPrCB included carbon bond cleavage and benzene ring opening. However, the methoxy group of ECTB reduced the nucleophilic reactivity on the benzene ring, leading to slower detoxification efficiency. These findings may help to develop LCMs treatment technologies based on structure-reactivity relationships.

Magnetic porous biochar with high specific surface area derived from microwave-assisted hydrothermal and pyrolysis treatments of water hyacinth for Cr(â ¥) and tetracycline adsorption from water.

Magnetic porous water hyacinth-derived biochar (MPBCMW3) was synthesized via two-step Microwave (MW)-assisted processes. Characterization results not only testified high specific surface area (2097.50 m2/g) of the MPBCMW3 assisted by MW-assisted pyrolysis, but also revealed its favorable magnetism derived from MW-assisted hydrothermal process. The MPBCMW3 possessed pH-dependent monolayer adsorption capacities of 202.61 and 202.62 mg/g for Cr(VI) and TC with quick attainments of uptake equilibrium within 150 and 200 min. Moreover, the Cr(VI) and TC uptake were substantially steady under the interference from multifarious co-existing ions with slight decline after three adsorption-desorption cycles. Furthermore, the MPBCMW3 was demonstrated to achieve excellent Cr(VI) binding primarily through complexation, electrostatic interaction, reduction and ion exchange, while presenting outstanding TC removal via pore filling, π-π stacking, hydrogen bonding force, electrostatic interaction and complexation. All these findings suggested the MPBCMW3 synthesized by MW-assisted processes as an excellent adsorbent for purification of Cr(VI) and TC-contaminated water.

Insight into the effects of hydroxyl groups on the rates and pathways of tetracycline antibiotics degradation in the carbon black activated peroxydisulfate oxidation process.

To investigate the effects of hydroxyl groups on the degradation of tetracycline antibiotics (TCs), three kinds of TCs [tetracycline (TC), oxytetracycline (OTC), and doxycycline (DTC)] were chosen as the target molecules and then degraded in the carbon black (CB)-activated peroxydisulfate (PDS) oxidation process. The degradation ratios of the TC, OTC, and DTC in the CB/PDS oxidation process reached 52%, 60%, and 87% within 40 min, respectively, with the degradation rate following the order of DTC > OTC > TC. According to the density functional theory calculations, these three TCs have different charge distributions, electrostatic potential distributions and average local ionization energy, which are caused by the distinct hydroxyl group position, thus contribute to the different degradation ratios and reaction rate constants. The hydrogenation of TC was slower special degradation pathway relative to those of OTC and DTC, while the decarbonylation of OTC was slower special degradation pathway relative to that of DTC, which adversely resulted in the degradation rate following the order of DTC > OTC > TC. This presentation gives a knowledge that the position and numbers of hydroxyl groups are pivotal to the degradation efficiency toward TCs.

Surface dual redox cycles of Mn(III)/Mn(IV) and Cu(I)/Cu(II) for heterogeneous peroxymonosulfate activation to degrade diclofenac: Performance, mechanism and toxicity assessment.

Advanced oxidation processes (AOPs) based on heterogeneous catalytic activated peroxymonosulfate (PMS) have been becoming alternatives to conventional wastewater treatment technologies to directly degrade chemical contaminants. To build dual/multi redox cycles of different metal ions may be an effective means for better PMS activation. Herein, this study designed Mn3O4/CuBi2O4 with dual redox cycles of Mn(III)/Mn(IV) and Cu(I)/Cu(II) to activate PMS for efficiently decomposing and mineralizing diclofenac sodium (DCF). Under optimal reaction conditions, DCF (50 mg/L) was degraded totally within 10 min, and TOC removal rate reached up to 74.3%. The possible mechanism of PMS activation by Mn3O4/CuBi2O4 was proposed, wherein dual redox cycles of Mn(III)/Mn(IV) and Cu(I)/Cu(II) on Mn3O4/CuBi2O4 effectively facilitated PMS activation to generate ·O2-, 1O2, SO4·- and ·OH, which was responsible for DCF degradation. Moreover, combined with degraded products detected by high resolution liquid chromatography coupled to mass spectrometry and corresponding toxic assessment results, the possible degradation pathways of DCF were proposed and the relative toxicity of degraded products was evaluated. This work may be useful for developing stronger heterogeneous activators of PMS to construct more efficient AOPs for purifying wastewater.

Near-infrared light to heat conversion in peroxydisulfate activation with MoS2: A new photo-activation process for water treatment.

The advantage of light-to-heat conversion can be employed as an optical alternative for environmental remediation. As a proof of concept, for the first time we introduce the light-to-heat conversion application in peroxydisulfate (PDS) activation by molybdenum disulphide (MoS2) under near infrared (NIR) light irradiation. Theoretical kinetics analysis suggests that the reaction rates of PDS activation is increased up to 9.2 times when increasing from room temperature to 50 °C. MoS2 has the capability to quickly convert NIR light to heat energy (~45°C), thereby being able to activate PDS to generate hydroxyl and sulfate radicals. The observed reaction rate of carbamazepine degradation by NIR/MoS2/PDS process is 6.5 times of that in MoS2/PDS and even 2.6 times higher than the sum of those in NIR/MoS2, MoS2/PDS and NIR/PDS processes. Combining with theoretical calculation and oxidation species analysis, a new photo-activation PDS mechanism is proposed, in which MoS2 absorbs the energy of light to generate heat energy for overcoming the energy barrier of PDS activation. By loading MoS2 on carbon cloths, a flexible photothermal membrane is designed for practical application of sunlight-to-heat conversion to activate PDS with high efficiency, stability, and recycling. The present results demonstrate the potential of applying light-to-heat conversion in Fenton-like processes in pollution control, which opens new avenues towards utilization of inexhaustible solar energy and novel approaches for environmental remediation.

Structure-dependent degradation of nitroimidazoles by cobalt-manganese layered double hydroxide catalyzed peroxymonosulfate process.

The increasing concentration of nitroimidazoles antibiotics (NIs) in the water environment has great threat to human and ecosystem security. Herein, the degradation rates of four NIs were found to vary with their molecular structures using Co3Mn-layered double hydroxide (LDH) catalyzed peroxymonosulfate oxidation process. Specifically, the degradation efficiency of secnidazole (SNZ) was determined to be the highest with a reaction rate of 0.24 min-1, which was 3.6, 2.3 and 1.8 times to that of menidazole (MZ), metronidazole (MTZ) and ornidazole (ONZ), respectively. During the reaction, 8.3% of Co2+ and 8.4% of Mn3+ transformed to Co3+ and Mn4+ after reaction, respectively. The conversion of bimetallic valence in Co3Mn-LDH donated electrons (e-) for PMS activation, resulting in the production of 1O2, OH, SO4- and O2-. Density functional theory (DFT) calculation showed that the presence of electron-donating groups (-CH3 and -OH) and the absence of electron-withdrawing atom (Cl) leaded to the richest active sites in the molecular structure of SNZ, which thus contributed to the highest degradation efficiency of SNZ. By deducing the structure-dependent degradation pathways of four NIs, the carbon chain of SNZ was found to be more easily attacked to form MTZ and MZ because of its unique active sites, resulting in the faster degradation rate of SNZ than MTZ and MZ. This study may provide a valuable insight into the effects of molecular structures on the degradation rates and transformation pathways of NIs.

In situ photoreduction of structural Fe(III) in a metal-organic framework for peroxydisulfate activation and efficient removal of antibiotics in real wastewater.

Structural Fe(III) is widely found in various coordination complexes and inorganic compounds. In this work, a typical Fe-based metal organic framework (MOF) (viz. MIL-100(Fe)) was chosen as an example in the activation of peroxydisulfate (PDS) for the removal of antibiotic pollutants. Interestingly, an auto-acceleration effect was observed in the process of MIL-100(Fe) activating PDS aided by visible light irradiation. Compared to the processes with MIL-100(Fe)-activated PDS alone and the photo-activated PDS alone, the degradation efficiency of sulfamethoxazole (SMX) obtained in the visible light assisted PDS activation by MIL-100(Fe) process was enhanced by 2.1 and 5.6 times, respectively. Therein, the photogenerated electrons from MIL-100(Fe) carried out an in situ reduction of the surface structural Fe(III) to form Fe(II), which in turn significantly improved the PDS activation efficiency in the generation of ·OH and O2-· radicals for the removal of SMX. The degradation pathways of SMX were deduced based on the experimental results and theoretical calculations. Acute toxicity estimation indicated the formation of less toxic products after the treatment of SMX. Additionally, degradation of five antibiotics in the real wastewater were investigated to further confirm the advantages of such in situ photoreduced structural Fe(III) in MOFs to activate the PDS process.

New insight into the substituents affecting the peroxydisulfate nonradical oxidation of sulfonamides in water.

The large consumption and discharge of sulfonamides (SAs) have potentially induced antibiotic resistance genes, posing inestimable threats to humans and ecosystems. In the present study, five SAs with different substituents were regarded as target compounds to be degraded using the nonradical dominated peroxydisulfate (PDS) activation process by the combination of 1O2 oxidation and direct electron transfer. The degradation rates, toxicities and pathways of SAs largely varied with their substituents. For instance, sulfathiazole with five-membered substituent had the highest degradation rate of 0.19 min-1, which was 3.8 times as the rate of sulfanilamide (0.05 min-1) without substituent. Then the theoretical calculation was adopted to further confirm that different substituents on the SAs could influence the molecular orbital distribution and their stability, thus resulting in the different removal rate of SAs. Finally, the products of different SAs were concisely deduced to take insight into the effects of different substituents on SAs degradation pathways. It was demonstrated that the geometrical differences among various SAs caused by the different substituents contributed to the different degradation pathways of SAs. Representatively, the special Smiles-type rearrangement pathway was occurred in the six-membered SAs instead of in the five-membered SAs, which inversely resulted in the slower degradation rate of six-membered SAs than the five-membered SAs. Thus, the present study provides a valuable insight into the effects of substituents on the degradation rate and transformation pathways of SAs in the nonradical PDS activation process.