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As a widely produced and used antibiotic, tetracycline (TC) has been frequently found in rivers, soil and drinking water. In this study, the degradation of TC was investigated by UV/Fe

Peroxymonosulfate (PMS) activation induced by tricobalt tetroxide spinel (Co

Exposure to amorphous silica nanoparticles (SiNPs) has increased dramatically, and concerns are growing about their potential health effects. However, their long-term systemic toxicity profile and underlying mechanisms following respiratory exposure still remains unexplored. It is well documented that the inhalation of ultrafine particles is firmly associated with adverse effects in humans. Environmental pollutants may contribute to diverse adverse effect or comorbidity in susceptible individuals. Thereby, we examined the long-term systemic effects of inhaled SiNPs using a sensitive mouse model (ApoE

Iohexol as an iodinated X-ray contrast agent is widely used, and it is the potential precursor for toxic iodinated disinfection by-products in the disinfection process. In this study, a series of CuFe

Artificial sweeteners have raised emerging concern due to their potential threats to human health, which were frequently detected in aquatic environment with median concentrations. Although current researches have widely reported that ultraviolet light-activated persulfate process (UV/PS) was superior to UV/H

The remediation of water polluted by fluroquinolones antibiotics remains an important issue. Although zero-valent copper (ZVC) coupled with molecular oxygen can destruct refractory organic pollutants, the activation efficiency still needs to be further improved. In this study, the introduction of ascorbic acid (AA) in ZVC/air process maintained a high-concentration of Cu(Ⅰ), which can efficiently activate molecular oxygen to generate reactive oxygen species (ROSs). Superoxide radicals and hydroxyl radicals coexisted in nZVC/AA/air system. The former contributed to the yield of H2O2 and also acted as a mediator for Cu(Ⅱ)/Cu(Ⅰ) redox cycles, the latter was the pivotal ROSs for ciprofloxacin (CIP) destruction. The CIP degradation decelerated through the addition of excessive nZVC and AA, and the optimum dosages of nZVC and AA were determined to be 0.2 g/L and 1 mM, respectively. The developed nZVC/AA/air process could efficiently operate in a relative broad pH range of 3.0–7.0, which was due to the fact that AA prevented the precipitation of copper ions in solution via forming stable chelates. The coexistence of Cl− severely retarded the CIP removal. According to the results of UPLC-MS/MS analysis and density functional theory calculations, the plausible degradation pathways including the decarboxylation, defluorination, hydroxylation and cleavage of C–C bond in piperazine ring were proposed.

Artificial sweeteners have raised emerging concern due to their potential threats to human health, which were frequently detected in aquatic environment with median concentrations. Although current researches have widely reported that ultraviolet light-activated persulfate process (UV/PS) was superior to UV/H2O2 process for the degradation of refractory organic contaminants, UV/H2O2 process presented a more satisfactory saccharin (SAC) removal efficiency than UV/PS process, completely degraded 20 mg/L SAC within 45 min. Hence, quenching and probe experiments were employed to investigate the difference between hydroxyl radical ( OH)- and sulfate radical (SO4 -)-mediated oxidation mechanisms, which revealed the higher reactivity of OH (1.37–1.56 × 109 M−1 s−1) toward SAC than SO4 - (3.84–4.13 × 108 M−1 s−1). A combination of density functional theory calculation and transformation products identification disclosed that OH preferred to attack the benzene ring of SAC via hydrogen atom transfer pathway, whereas SO4 - oxidation was conducive to the cleavage of -C-NH2 bond. Increasing oxidant concentration significantly accelerated SAC degradation in both processes, while UV/H2O2 process consumed lower electrical energy with respect to UV/PS process. Additionally, UV/H2O2 system presented excellent adaptability and stability under various water matrices parameters (e.g. pH, anions and humic acid). While both UV/H2O2 and UV/PS processes promoted the generation of disinfection by-products (DBPs) during subsequent chlorination, and prolonging pretreatment time posed positive effect on reducing the formation of DBPs. Overall, the results clearly demonstrate the high efficiency, economy and practicality of UV/H2O2 process in the remediation of SAC-contaminated water.

Cementitious membrane (CM) is a promising microfiltration membrane with low cost for raw materials and low energy consumption of non-sintering fabrication process. A novel carbon-cementitious microfiltration membrane (CCM) was fabricated with powdered activated carbon (PAC) as an additive based on CM, to solve the low mechanical strength of CM during multiple practical uses. While maintaining adequate pure water flux and porosity, the mechanical strength of the membrane was greatly improved to ensure the stability of the membrane in the filtration process. The bending strength of the CCM was 2–3 times higher than that of CM. 10 wt% CCM has the smallest critical pore size and optimal permeability, which was chosen to be the optimal PAC doping ratio. The X-ray diffraction and FT-IR results indicated that the addition of PAC did not change the mineral composition of cement hydration products, and the appropriate amount of PAC acted as a nucleation site and accelerated hydration. The effect of size effect on bending strength was more obvious with the decrease of membrane thickness. In the membrane adsorption experiments of benzophenone-4, nitrobenzene and p-chloronitrobenzene, the CCM exhibited prominent adsorption properties than CM. These results broaden the application scope of microfiltration membranes in water treatment process.

N,N-Diethyl-3-methyl benzoyl amide (DEET) has been detected as an emerging pollutant in various water bodies because of its widespread use as an insect repellent. In this study, the combination of UV-LED275 and iron-containing coagulant (FeCl3) was used for the elimination of DEET in water. It was found that UV-LED275/FeCl3 (98 %) system presented a favorable removal of DEET compared with UV254/FeCl3 (59 %) and UV-LED275/Fe2(SO4)3 (81 %) processes at initial pH 3.5. DEET degradation by both UV-LED275/FeCl3 and UV-LED275/Fe2(SO4)3 processes followed pseudo-first-order kinetics with the calculated pseudo-first-order rate constants (kobs) of 0.0105 and 0.0046 cm2 mJ−1, respectively. The results of ESR analysis and radicals quenching experiments indicated that hydroxyl radicals ( OH) and superoxide radicals (O2− ) were responsible for DEET degradation in UV-LED275/FeCl3 process, and the former played the major role. An increase in FeCl3 dosage was beneficial to the degradation. In the UV-LED275/FeCl3 process, DEET degradation increased with a decrease in pH from 3.5 to 3.0, whereas it was almost completely suppressed with an increase in pH from 4.3 to 6.3. DEET degradation was almost unchanged after the introduction of NO3−, and it impeded after the addition of humic acid (HA), HCO3−, and SO42−. The plausible degradation pathway mainly involved hydroxylation, cleavage of the C–N bond, acetylation, and dealkylation. Among the disinfection by-products (DBPs) evaluated, UV-LED275/FeCl3 pretreatment generally increased the generation of trichloromethane, chloral hydrate, dichloroacetic acid, and trichloroacetic acid, which implied that further assessment of environmental risk was needed during its practical applications.

The degradation of N,N-diethyl-meta-toluamide (DEET) in aqueous solution by the UV/monochloramine (UV/NH2Cl) process was examined systematically in this study. DEET was resistant to UV photolysis and chloramination, while the synchronous combination of UV irradiation and NH2Cl can effectively eliminate DEET, which was caused by the generation of hydroxyl radicals and reactive chlorine species. The former played the critical role in DEET degradation, while the contribution of the latter can be ignored. Under all investigated experimental conditions, DEET degradation in the UV/NH2Cl process followed the pseudo-first-order kinetic model. The water quality parameters exerted the complicated impact. Reducing solution pH and raising water temperature both favored the DEET removal. The presence of sulfate, humic acid and fulvic acid accelerated the degradation, while the introduction of bicarbonate and high-concentration chloride retarded the removal. The plausible degradation pathways of DEET in the UV/NH2Cl process were proposed through the combination of QTOF/MS analysis and DFT calculation, and mainly involved in the cleavage of C–N bond, dealkylation, mono- and polyhydroxylation. The acute toxicity of reacted solution underwent a trend of first increasing and then decreasing with the prolonged irradiation time, which can be well illustrated by quantitative structure-activity relationship analysis. Electrical energy per order was employed to determine the energy consumption and the optimal conditions were determined as UV fluence of 369.9–493.2 mJ cm−2 and NH2Cl dosage of 5–20 mg L−1.