•FSO/PMC exhibited highly catalytic performance during the ozonation of DCF.•The formation of OH radicals and H2O2 was investigated.•The role of oxidation in FSO/PMC catalytic ozonation was discussed.•The effect of FSO/PMC’ adsorption on ozone and organic intermediates was examined.The mechanism of enhanced diclofenac (DCF) mineralization by catalytic ozonation over iron silicate-loaded pumice (FSO/PMC) was investigated. The results showed that FSO/PMC catalytic ozonation process significantly improved the DCF mineralization from 32.3% (sole-ozonation) to 73.3%. The adsorptive and catalytic properties of FSO/PMC effectively enhanced the oxidative capability of ozone and led to an excellent DCF mineralization. This is likely due to the presence of FSO/PMC that can improve the mass transfer of aqueous ozone, increase the solubility of aqueous ozone, and accelerate the generation of OH radicals as verified in this study. The adsorption of DCF on FSO/PMC was low (7.3%), however, DCF could be rapidly decomposed into various intermediates, which have much higher adsorption on FSO/PMC surface than that of DCF. This is another critical finding to justify the higher and faster TOC removal, because the accumulation (i.e. adsorption) of various intermediates on the surface of FSO/PMC increases their contact probability with OH radicals that derived from ozone decomposition. The ozone decomposition on the catalyst surface can further accelerate a benign cycling of the succeeding ozone gas transfer, H2O2 generation, and adsorption/decomposition of intermediates.

In the present study, zebrafish embryos were used to assess the neurotoxicity of di-n-butyl phthalate (DBP), diethyl phthalate (DEP) and their mixture. Four-hour post-fertilization (hpf) zebrafish embryos were exposed to various concentrations of DBP, DEP and their mixture (DBP–DEP) until 96 hpf. The transcriptions levels of selected neuron-related genes reported as neurotoxicity biomarkers were analyzed. The results showed that transcripts of growth associated protein 43 (gap43), embryonic lethal abnormal vision-like 3 (elavl3), glial fibrillary acidic protein (gfap), myelin basic protein (mbp), α1-tubulin and neurogenin1 (ngn1) were significantly up-regulated after DBP, DEP and DBP–DEP mixture exposure. In addition, acetylcholinesterase activity was significantly inhibited in the embryos. These results indicate that DBP and DEP have the potential neurotoxicity in zebrafish embryos.

Temperature-controlled ionic liquid dispersive liquid–liquid microextraction (TC-IL-DLLME) was introduced to analyze malachite green (MG) and crystal violet (CV) in environmental water by coupling with high performance liquid chromatography (HPLC). In the method, 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) and methanol were selected as appropriate extraction and dispersive solvents, respectively. Target compounds were extracted into the IL phase (dispersed completely in the aqueous phase) at a proper temperature. Several other parameters that could affect extraction performance were optimized, such as IL volume, sample pH, salinity, extraction time, temperature and centrifuging velocity. Under the optimum conditions (IL volume, 80 μL; sample pH, 4; salinity, 20% sodium chloride; extraction time, 50 min; temperature, 70 °C; centrifuging velocity, 1500 rpm), the established method offered: (i) good linear range (0.25–20 μg L−1); (ii) low detection limits (MG, 0.086 μg L−1; CV, 0.030 μg L−1); (iii) good reproducibility (relative standard deviation, MG, 9.4%; CV, 7.6%; n = 5) and good recoveries (91.7% for MG and 97.2% for CV, respectively; n = 5); (iv) high enrichment factor (254 for MG, 276 for CV), which makes the method suitable to monitor low concentrations of MG and CV in aqueous systems.

Previous studies have linked nitrosamine formation during ozonation to a nitrosation process in which nitrosation is catalyzed by formaldehyde, a normal byproduct of ozonation. This mechanism cannot explain the increase in N-nitrosodimethylamine (NDMA) formation with an increase of pH. This study reinvestigates the pathway of N-nitrosamine formation during ozonation. Our observations demonstrated the critical importance of some reactive inorganic nitrogenous intermediates, such as hydroxylamine and dinitrogen tetroxide (N2O4). We report two alternative pathways that possibly explain nitrosamine formation during ozonation at neutral and alkaline pH: (i) secondary amine precursors reacting with hydroxylamine to form unsymmetrical dialkylhydrazine intermediates, which are further oxidized to their relevant nitrosamines; and (ii) a nitrosation pathway in which N2O4 acts as the nitrosating reagent. The key variables of pathway (i) (including reaction time, pH, dissolved oxygen) were investigated. Since hydroxylamine is a common intermediate of dimethylamine oxidation, it is reasonable to assume that hydroxylamine is a possible inorganic precursor for NDMA formation during oxidation processes using strong oxidants. With an improved understanding of the pathway of nitrosamine formation, it should be apparent that the reactive nitrogenous intermediates play an important role in the N-nitrosamine-formation, so future studies of N-nitrosamine-formation control should be focused on the transformation of nitrogen in water treatment.

Large-scale β-Co(OH)2 hexagonal nano-platelets have been synthesized successfully at 70 °C using only CoCl2 and NaOH as reactants. The physicochemical features of the β-Co(OH)2 hexagonal nano-platelets were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and nitrogen absorption–desorption. Results showed that the β-Co(OH)2 obtained consisted of thin, regular, hexagonal nano-platelets with diameters and thicknesses of 50–300 nm and 30–80 nm, respectively. A transformation from β-Co(OH)2 to Co3O4 was observed in the temperature range 160–220 °C. The average pore-size and the Brunauer–Emmet–Teller (BET) surface area of the synthesized β-Co(OH)2 were 16.76 nm and 29.45 m2/g. The prepared product had a significant effect on the catalytic decomposition of ozone.

In order to provide basic data for practical application, photodegradation experiment of N-nitrosodimethylamine (NDMA) in aqueous solution was carried out with a low-pressure Hg lamp. Effects of the initial concentration of NDMA, solution pH, dissolved oxygen, and the presence of humic acid on NDMA photodegradation were investigated. NDMA at various initial concentrations selected in this study was almost completely photodegraded by UV irradiation within 20 min, except that at 1.07 mmol/L, NDMA could be photodegraded almost completely in the acidic and neutral solutions, while the removal efficiency decreased remarkably in the alkaline solution. Dissolved oxygen enhanced the NDMA photodegradation, and the presence of humic acid inhibited the degradation of NDMA. Depending on the initial concentration of NDMA, NDMA photodegradation by UV obeyed the pseudo-first-order kinetics. Dimethylamine, nitrite, and nitrate were detected as the photodegradation products of NDMA. 1O2 was found to be the reactive oxygen species present in the NDMA photodegradation process by UV, based on the inhibiting experiments using tert-butanol and sodium azide.

•HA inhibits the leaching concentration for some elements by complexes −coprecipitation.•High concentration of HA could affect the formation of gismondine obtained from FA hydration process.•Free-CaO is the most critical factor influencing the adsorption performance and leaching behavior of FA.•Adding CaO could increase the types of hydration products, which maybe inhibit the leaching of some elements from FA.As a low-cost material for adsorption, FA is one of the most efficient adsorbents of HA. However, the leaching of elements from FA is problematic during utilization in water treatment. In this investigation, the potential leaching behaviors of Calcium, Arsenic, Born, Chromium, and other elements from FA in HA solution were studied via batch test. The data show that HA had an effect on the leaching of each element of FA, depending on the pH, the initial concentration of HA and the addition of calcium oxide (CaO). The Langmuir isotherm could better fit the equilibrium data in different initial concentrations of HA from 10 to 100 mg/L. Because of the interaction between HA and the FA leaching elements, multi-layer adsorption occurred when the initial concentration of HA was more than 100 mg/L. The pH and free CaO content played major roles in HA adsorption and FA leaching. Using SEM and XRD to characterize the solid of FA being mixed with CaO treated in solution, the results demonstrated that the reaction between FA and CaO could generate crystal minerals, such as portlandite, gismondine, ettringite (AFt) and calcite, which effectively restrained the leaching of elements, reduced secondary pollution.

Temperature-controlled ionic liquid dispersive liquid–liquid microextraction (TC-IL-DLLME) was introduced to analyze malachite green (MG) and crystal violet (CV) in environmental water by coupling with high performance liquid chromatography (HPLC). In the method, 1-octyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) and methanol were selected as appropriate extraction and dispersive solvents, respectively. Target compounds were extracted into the IL phase (dispersed completely in the aqueous phase) at a proper temperature. Several other parameters that could affect extraction performance were optimized, such as IL volume, sample pH, salinity, extraction time, temperature and centrifuging velocity. Under the optimum conditions (IL volume, 80 μL; sample pH, 4; salinity, 20% sodium chloride; extraction time, 50 min; temperature, 70 °C; centrifuging velocity, 1500 rpm), the established method offered: (i) good linear range (0.25–20 μg L−1); (ii) low detection limits (MG, 0.086 μg L−1; CV, 0.030 μg L−1); (iii) good reproducibility (relative standard deviation, MG, 9.4%; CV, 7.6%; n = 5) and good recoveries (91.7% for MG and 97.2% for CV, respectively; n = 5); (iv) high enrichment factor (254 for MG, 276 for CV), which makes the method suitable to monitor low concentrations of MG and CV in aqueous systems.