Display omitted
•Peroxymonosulfate and electrolysis have synergistic effect on the degradation of CECs.•The mechanism of electrochemically activated peroxymonosulfate is proposed.•A prediction model ...on the effect of water matrices on SMX removal is built using RSM.•Electrochemically activated peroxymonosulfate has great potential for application.
Electrochemically activated persulfate is an emerging advanced oxidation process for the removal of contaminants of emerging concern (CECs). The degradation of CECs, including carbamazepine (CBZ), bisphenol S (BPS), propranolol (PPL) and sulfamethoxazole (SMX) using electrochemically activated peroxymonosulfate (EA-PMS) was systematically investigated in this work. Over 80% of all the forementioned CECs were removed within 30 min. It exhibited a good synergistic effect between PMS and electrolysis on the degradation of CECs. The results of linear sweep voltammetry (LSV) indicated that a transition structure between BDD anode and PMS (BDD (PMS)*) was likely responsible for the synergistic effect. Hydroxyl radical (HO·) and sulfate radical (SO4·−) were proved to be the primary reactive species, of which HO· played the leading role. The increase of current density and PMS dosage accelerated the degradation of SMX, while initial pH from 3.0 to 11.0 had a limited effect on the degradation of SMX. Moreover, the influences of common ions and natural organic matter (NOM) on the degradation of SMX were comprehensively assessed using response surface methodology (RSM), and a prediction model was built via RSM. The performance of EA-PMS on the degradation of SMX in actual water was even better than that in pure water in this study. EA-PMS can serve as a novel and promising technology for the degradation of CECs and has great potential in practical application.
Electro-peroxone (EP) is an emerging advanced oxidation process which combines electro-generation H2O2 and ozone for removing organic contaminants. In this paper, a platinum plate as anode, a method ...of electrochemical oxidation is adopted to modify graphite felt (GF) cathode to promote H2O2 yield and TOC removal from oxalic acid solution in EP process, its performance, mechanism and stability were discussed. Compared with original GF cathode, 2.6 times H2O2 yield can be achieved by the 5 min electrochemically modified GF (GF-5). The high electrochemical activity of the modified GF can be ascribed to introducing numerous surface oxygen-containing functional groups (OGs), which not only decreased the impedance, but also increased the amount of active site of O2 reduction. The production of H2O2 with GF-5 cathode improved with the increased initial pH, cathodic potential and O2 flow rate, while this promoting effect was not observed in GF cathode. Compared with GF cathode, TOC removal rate was improved by 21.5% with GF-5 cathode due to higher H2O2 yield in EP process. The primary pathway of TOC removal is electrochemically-driven peroxone process, and hydroxyl radical (·OH) is the dominant reactive species. Furthermore, GF-5 cathode had a good stability due to the protection of H2O2 and free electrons injected. The results indicate that the electrochemically modified GF severed as the cathode of EP processes has significant efficiency and stability in the removal of ozone-refractory organic contaminants.
Display omitted
•Electrochemical oxidation was firstly adopted to modify GF cathode of EP process.•The introduction of OGs significantly promoted H2O2 yield and enhanced TOC removal.•TOC removal from OA solution reached 79.5% in EP process with modified GF cathode.•EIS method was firstly adopted to reveal the reason for high current response.•The modified GF had good stability in electro-peroxone process for TOC removal.
Electro-peroxone (EP) is a novel technique for the removal of refractory organic contaminants (ROCs), while the role of anode in this system is neglected. In this work, the EP system with graphite ...felt anode (EP-GF) and activated carbon fiber anode (EP-ACF) was developed to enhance ibuprofen (IBP) removal. The results showed that 91.2% and 98.6% of IBP was removed within 20 min in EP-GF and EP-ACF, respectively. Hydroxy radical (O⋅H) was identified as the dominant reactive species, contributing 80.9% and 54.0% of IBP removal in EP-ACF and EP-GF systems, respectively. The roles of adsorption in EP-ACF and direct electron transfer in EP-GF cannot be ignored. Due to the differences in mechanism, EP-GF and EP-ACF systems were suitable for the removal of O⋅H-resistant ROCs (e.g., oxalic acid and pyruvic acid) and non-O⋅H-resistant ROCs (e.g., IBP and nitrobenzene), respectively. Both systems had excellent stability relying on the introduction of oxygen functional groups on the anode, and their electrolysis energy consumption was significantly lower than that of EP-Pt system. The three degradation pathways of IBP were proposed, and the toxicity of intermediates were evaluated. In general, carbon anodes have a good application prospect in the removal of ROCs in EP systems.
Display omitted
•GF and ACF anodes exhibited the excellent performance for the IBP removal in EP system.•O⋅H was dominant reactive species, contributing 80.9% to IBP removal in EP-ACF system.•O⋅H and DET separately contributed 54.0% and 33.0% to IBP removal in EP-GF system.•EP-GF system showed the superior stability due to the introduced OGs on GF anode.
Electrochemically activated peroxymonosulfate with mixed metal oxide electrodes (EA-PMS-MMO/MMO) is an emerging advanced oxidation process. It performed well on the degradation of sulfadiazine (SDZ), ...whose removal rate reached 81.13% within 30 min. Both the MMO anode and cathode played an irreplaceable role in PMS activation. HO•, SO4•-, O2•- and 1O2 were confirmed to be the major reactive species in the system, among which 1O2 was the most abundant. The generation mechanism of the reactive species and the overall mechanism of the system were proposed. Four degradation pathways of SDZ were speculated based on density functional theory. The acute and chronic toxicity of SDZ and its degradation intermediates was evaluated by the quantitative structure-activity relationship method, and the overall toxicity was significantly reduced after the degradation by EA-PMS-MMO/MMO. The results show that EA-PMS-MMO/MMO affords a reliable technology for the degradation of organic contaminants and has promising potential for application.
Display omitted
•Both the MMO anode and cathode play an irreplaceable role in the activation of PMS.•1O2 was the most abundant reactive specie among HO.•, SO4•-, O2•- and 1O2.•The degradation pathways of SDZ are speculated based on DFT and LC-MS detection.•The toxicity of SDZ can be significantly reduced after full oxidation by EA-PMS-MMO/MMO.
In this study, the tips of Myriophyllum aquaticum (M. aquaticum) plants were planted in open-top plastic bins and treated by simulated wastewater with various ammonium-N concentrations for three ...weeks. The contents of related carbohydrates and key enzyme activities of carbon metabolism were measured, and the mechanisms of carbon metabolism regulation of the ammonia tolerant plant M. aquaticum under different ammonium-N levels were investigated. The decrease in total nonstructural carbohydrates, soluble sugars, sucrose, fructose, reducing sugar and starch content of M. aquaticum were induced after treatment with ammonium-N during the entire stress process. This finding showed that M. aquaticum consumed a lot of carbohydrates to provide energy during the detoxification process of ammonia nitrogen. Moreover, ammonia-N treatment led to the increase in the activitives of invertase (INV) and sucrose synthase (SS), which contributed to breaking down more sucrose to provide substance and energy for plant cells. Meanwhile, the sucrose phosphate synthase (SPS) activity was also enhanced under stress of high concentrations of ammonium-N, especially on day 21. The result indicated that under high-concentration ammonium-N stress, SPS activity can be significantly stimulated by regulating carbon metabolism of M. aquaticum, thereby accumulating sucrose in the plant body. Taken together, M. aquaticum can regulate the transformation of related carbohydrates in vivo by highly efficient expression of INV, SPS and SS, and effectively regulate the osmotic potential, thereby delaying the toxicity of ammonia nitrogen and improving the resistance to stress. It is very important to study carbon metabolism under ammonia stress to understand the ammonia nitrogen tolerance mechanism of M. aquaticum.
Display omitted
•The decrease in carbohydrates of M. aquaticum was induced by ammonium-N treatment.•Enhanced activitives of INV, SS and SPS were observed under ammonium-N stress.•Carbohydrates in vivo can be regulated by enhancing INV, SS and SPS activitives.
AbstractThe novel Fe-doped MoS2/granulated activated carbon (GAC) particle electrodes (FMG PEs) were controllably synthesized by a hydrothermal method and used in the three-dimensional (3D) ...electroactivation of peroxydisulfate (E-PDS-FMG) for carbamazepine (CBZ) degradation. The performance, mechanism, and influencing factors of CBZ degradation by the E-PDS-FMG system were systematically discussed. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyses showed that the E-PDS-FMG system has an excellent conductivity and a high electron transfer rate and exhibited a superior electrocatalytic performance for CBZ degradation. A CBZ removal rate greater than 99% can be achieved within 25 min under the conditions of FMG dosage of 0.4 g L−1, PDS concentration of 2.0 mM, current density of 1.0 mA cm−2, and initial pH value of 5. Sulfate radicals (SO4·−) and hydroxyl radicals (OH) were recognized as the major active species through quenching experiments and electron paramagnetic resonance (EPR) measurement. In addition, Fe (IV) was also involved in the E-PDS-FMG system according to the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2). Furthermore, the possible mechanism of the E-PDS-FMG system was proposed. FMG PEs were applied as the catalyst and particle electrodes for PDS activation, improving the yield of OH, SO4·−, and Fe (IV). The increase of FMG dosage and PDS concentration accelerated the degradation of CBZ, and the E-PDS-FMG system exhibited a high degradation ability on CBZ removal in a wide pH range. The results all indicate that the E-PDS-FMG system is a promising technology for organic pollutant removal from water due to its excellent electrocatalytic performance and remarkable stability.
Display omitted
•Alkali-washed loofah-like CTS/SA-m for low concentration ClO4− were fabricated.•Over 95 % of ClO4− removal rate achieved in 10 mins with initial concentration of ...10 mg/L.•Chemisorption was identified as dominant process with a rate of 3.24 mg/(g·min).•DFT revealed impact of functional groups on ClO4− adsorption: –NH3+ > –COOH > –NH2 > –OH.
Perchlorate, an emerging contaminant in drinking water, has attracted global attention. In this study, a novel loofah-like porous chitosan/alginate composite aerogel (CTS/SA-m) was fabricated using ionotropic pregelation and freeze-dried technology to effectively adsorb perchlorate. The performance, isotherms, thermodynamics, and kinetics of perchlorate adsorption by CTS/SA-m were systematically discussed. The results showed that the loofah-like CTS/SA-m with high hydrophilicity exhibited excellent adsorption properties. Over 95 % of the removal rate in 10 min can be achieved, with initial concentration of perchlorate and CTS/SA-m dosage of 10 mg/L and 2 g/L, respectively. And 70.15 mg/g of equilibrium adsorption capacity of perchlorate could be reached at pH 5 and 298 K. pH had little effect on the removal rate of perchlorate, the removal rate surpassed 85 % over a wide pH range of 3.0–11.0. Multilayer adsorption (MLA), intraparticle diffusion (IPD), and adsorption on the active site (AOAS) models were employed to discuss the adsorption mechanism of perchlorate. It was confirmed that double-layer chemisorption played a dominant role. Density functional theory (DFT) analysis of binding energy revealed the effect of functional groups on the ClO4− adsorption strength in the order of –NH3+ > –COOH > –NH2 > –OH. Furthermore, electrostatic potential and the independent gradient model confirmed that electrostatic interactions, hydrogen bonding, and van der Waals forces contributed to the highly efficient adsorption of perchlorate. These findings have a vital promoting effect on perchlorate removal technology in water treatment. Moreover, the loofah-like CTS/SA-m aerogel material, exhibiting outstanding performance, shows great potential in effectively in trapping perchlorate anions from aquatic systems.
Microplastics (MPs), the emerging pollutants appeared in water environment, have grabbed significant attention from researchers. The quantitative method of spherical MPs is the premise and key for ...the study of MPs in laboratory researches. However, the manual counting is time-consuming, and the existing semi-automated analysis lacked of robustness. In this study, a highly accurate quantification method for spherical MPs, called VS120-MC was proposed. VS120-MC consisted of the digital slide scanner VS120 and the MPs image processing software, MPs-Counter. The full-area scanning photography was employed to fundamentally avoid the error caused by random or partition sampling modes. To accomplish high-performance batch recognition, the Weak-Circle Elimination Algorithm (WEA) and the Variable Coefficient Threshold (VCT) was developed. Finally, lower than 0.6% recognition error rate of simulated images with different aggregated indices was achieved by MPs-Counter with fast processing speed (about 2 s/image). The smallest size for VS120-MC to detect was 1 μm. And the applicability of VS120-MC in real water body was investigated. The measured value of 1 μm spherical MPs in ultra-pure water and two kinds of polluted water after digestion showed a good linear relationship with the Manual measurements (R2 = 0.982,0.987 and 0.978, respectively). For 10 μm spherical MPs, R2 reached 0.988 for ultra-pure water and 0.984 for both of the polluted water. MPs-Counter also showed robustness when using the same set of parameters processing the images with different conditions. Overall, VS120-MC eliminated the error caused by traditional photography and realized an accurate, efficient, stable image processing tool, providing a reliable alternative for the quantification of spherical MPs.
•Full-area photography and semi-automatic image recognition of spherical microplastics were implemented.•Accurate quantification of spherical microplastics in both clean or polluted water for the size limit of 1 μm.•Efficient and stable batch process of microplastics images can be achieved by the homemade software MPs-Counter.•The average processing time for MPs-Counter was 2 s/image, saving about 10 times of manual counting.
Capture of radioactive iodine has been paid much attention due to the release of radioactive iodine from nuclear accident and metal fission. Deep eutectic solvents (DESs) are green solvents. ...Polyethylene glycol (PEG) possesses the merits of no toxicity, high biocompatibility, high biodegradation and low cost. Here, we for the first time design a series of PEG-based DESs for efficient iodine capture. PEG:thiourea+ethanol mixture owns the highest rate and capacity for iodine capture. Effect of mass, mol ratio, organic solvent, molecular weight of PEG and composition of DESs on iodine capture is investigated. W = W∞(1 − e−kx) is first fitted for DESs to capture iodine. Conventional, difference and the PCMW2D-COS UV–Vis spectra show that PEG:thiourea+ethanol interacts with iodine mainly via halogen bonds before 75 min and via induced force after 75 min. The iodine-capturing rate by PEG:thiourea+ethanol is slightly higher than that of the reported DESs with the highest efficiency while in the same condition. Although the presence of volatile ethanol in PEG:thiourea decreases the iodine storage efficiency, it would provide a new route of improving iodine-capturing rate and capacity.
Display omitted
•PEG-based DESs is highly biocompatible and green.•PEG-based DESs captures iodine for the first time.•High efficiency and rate
