AhR agonists screening and identification in indoor dust based on non-target chemical analysis by GC-Q-TOFMS and biological effect evaluation referring to ToxCast/Tox21 database.

Numerous studies reported the concentration of agonists of aryl hydrocarbon receptor (AhR) in indoor dust by target chemical analysis or the biological effects of activating the AhR by indoor extracts, but the major AhR agonists identification in indoor dust were rarely researched. In the present study, the indoor dust samples were collected for 7-ethoxyresorufin O-deethylase (EROD) assay and both non-targeted and targeted chemical analysis for AhR agonists by gas chromatography quadrupole time-of-flight mass spectrometry and gas chromatography-mass spectrometry analysis. Coupled with non-targeted analysis and toxicity Forecaster (ToxCast)/Tox21 database, 104 ToxCast chemicals were screened to be able to induce EROD response. The combination of targeted chemical analyses and biological effects evaluation indicated that PAHs, dibutyl phthalate (DBP) and Cypermethrin might be the important AhR-agonists in different indoor dust and mainly contributed in 1.84%-97.56 % (median: 26.62%) of total observed biological effects through comparing toxic equivalency quotient derived from chemical analysis with biological equivalences derived from bioassay. DBP and cypermethrin seldom reported in the analysis of AhR agonists should raise great concern. In addition, the present results in experiment of synthetic solution of 4 selected AhR-agonists pointed out that some unidentified AhR agonists existed in indoor dust.

Impact of non-aged and UV-aged microplastics on the formation of halogenated disinfection byproducts during chlorination of drinking water and its mechanism.

Microplastics (MPs) are ubiquitously present in source water and undergo ultraviolet (UV) aging in aquatic environments before entering drinking water treatment plants. The presence of MPs in drinking water can impact the formation of halogenated disinfection byproducts (DBPs) during chlorine disinfection, yet the exact effect of MPs on DBP formation remain unclear. In this study, we conducted an investigation into the influence of non-aged and UV-aged MPs on halogenated DBP formation in drinking water and unveiled the underlying mechanisms. In comparison to source water samples devoid of MPs, the total organic halogen concentration was reduced by 19%-43% and 4%-13% in the drinking water samples containing non-aged and aged MPs, respectively. The differing effects on halogenated DBP formation can be attributed to the alternation in physical and chemical characteristics of MPs following UV aging. Aged MPs exhibited larger surface area with signs of wear and tear, heightened hydrophilicity, surface oxidation, increased oxygen-containing functional groups and dechlorination during the UV aging process. Both non-aged and aged MPs possess the capability to adsorb natural organic matter, leading to a reduction in the concentration of DBP precursors in the source water. However, the release of organic compounds from aged MPs outweighed the adsorption of organics. Furthermore, as a result of the surface activation of MPs through the UV aging process, the aged MPs themselves can also serve as DBP precursors. Consequently, the presence of halogenated DBP precursors in source water increased, contributing to a higher level of DBP formation compared to source water containing non-aged MPs. Overall, this study illuminates the intricate relationship among MPs, UV aging, and DBP formation in drinking water. It highlights the potential risks posed by aged MPs in influencing DBP formation and offers valuable insights for optimizing water treatment processes.

Efficient treatment of surfactant containing wastewater by photocatalytic ozonation with BiPO4 nanorods.

In this study, monoclinic BiPO4 nanorods were fabricated by one-pot solvothermal method. Its catalytic capability in photocatalytic ozonation process was tested by degradation and mineralization of sodium dodecyl benzene sulfonate (SDBS) solution. The results demonstrated that the TOC removal rate was dramatically improved to 90.0% at 75 min for UV/O3/BiPO4 process, which was 4.9 and 3.8 times more than that of UV/BiPO4 and O3. Moreover, the pseudo-first-order kinetic constant (0.337 min-1) and mineralization rate (90.0%) for SDBS degradation using BiPO4 in UV/O3 process were 1.6 and 1.3 times as great as that of conventional TiO2 photocatalyst (0.206 min-1, 67.3%). The influence of BiPO4 dosage, O3 concentration initial pH and coexisted ions on SDBS degradation in UV/O3/BiPO4 process were also investigated. The outcome of quenching studies illustrated both ·OH and h+ contributed prominently to SDBS degradation in UV/O3/BiPO4 process, implying that high valence band position of BiPO4 could promote the synergism between photocatalysis and ozonation. The degradation pathway of SBDS was proposed by combination of intermediates analysis and DFT calculation. Real carwash wastewater was chosen as typical surfactant containing wastewater to explore the practical application of UV/O3/BiPO4 technology. During 30 min, COD and LAS removal efficiency reached 59.7% and 70.6%, respectively. The quality indices of effluent could meet the requirements for reuse of carwash water in Water Quality Standard for Urban Miscellaneous Use in China. Energy consumption in the process was calculated as 13.9 kW h m-3, which was about 3.6 and 2.2 times less than that of UV/BiPO4 and O3 process, respectively. The results suggest that UV/O3/BiPO4 system has an application potential for surfactant containing wastewater treatment or recycle.

Diverse performances for Pb(II) adsorption by in situ formed Fe(III) oxyhydroxide derived from ferrate(VI) reduction and ferrous oxidation.

Two in situ formed Fe(III) oxyhydroxides (FeOx) originated from ferrate reduction (designated FeOx-FeVI) and ferrous oxidation by H2O2 (designated FeOx-FeII) were compared in the aspects of morphology, hydrolyzed species, surface binding mechanism of lead. The theoretical maximum adsorption capacity calculated from the Langmuir model toward Pb(II) was 929.54 and 810.37 mg/g Fe by FeOx-FeVI and FeOx-FeII, respectively. At pH 6 and the same Fe/Pb ratio, the kinetic rate of Pb removal by the FeOx-FeVI process was 8 times faster. FTIR, SEM, and Ferron assay suggest FeOx-FeVI was associated with a lesser polymerization degree and contained more reactive hydroxyl-Fe polymers than those in the FeOx-FeII sample. SAXS verified that the particles possessed a smaller, more homogeneous, and open structure when Fe was hydrolyzed by ferrate reduction than ferrous oxidation. XPS coupled with fractal analysis suggests the different sorption capacities of Pb(II) can be ascribed to their distinct growth patterns. Fast cluster agglomeration during FeOx-FeII fabrication decreased the exposure of effective adsorption sites. In comparison, the incompact assemblies of FeOx-FeVI clusters facilitated Pb(II) ions to access the interstices of octahedral FeO6 units and formed an edge-sharing complex. This work provides new insight into mechanisms of particle fabrication and heavy metal removal of Fe(III) formed in situ.

Inhalation bioacessibility and lung cell penetration of indoor PM2.5-bound PAEs and its implication in risk assessment.

Several studies have evaluated the human exposure of phthalate esters (PAEs) in PM2.5 via inhalation route, however, inhalation bioaccessibility and the lung cell penetration of PAEs were barely considered in risk assessment. In the present study, PM2.5 samples collected from indoor environments were investigated for inhalation bioaccessibility of PAEs using two simulated lung fluids (gamble's solution (GMB) and artificial lysosomal fluid (ALF)). The results showed that the inhalation bioaccessibility of PAEs (except for diethyl phthalate) under healthy state (GMB: 8.9%-62.8%) was lower than that under the inflammatory condition (ALF: 14.5%-67.6%). Lung cell permeation and metabolism of three selected PAEs (diethyl phthalate, di(n-butyl)phthalate and di-2-ethylhexyl phthalate) was tested using equivalent lung cell (A549) model. The inhalation bioavailability obtained by combination of the bioaccessibility of PAEs in indoor PM2.5 and permeability data of A549 cell ranged from 11.7% to 51.1% in health condition, and 13.5%-55.0% in inflammatory state. The calibration parameter (Fc) based on the inhalation bioavailability was established in present study and could provide a reference for a more accurate risk assessment of PM2.5-bound PAEs.

Enhanced Adsorption of Bromoform onto Microplastic Polyethylene Terephthalate Exposed to Ozonation and Chlorination.

This paper selected microplastic polyethylene terephthalate (PET), commonly found in water/wastewater plant effluent, to investigate the changes of PET oxidized under ozonation (designated as ozonized PET), followed by sodium hypochlorite oxidation (designated as ozonized-chlorinated PET) and studied their influence on the adsorption of the disinfection by-product bromoform (TBM). Fragmentation and cracks appeared on the oxidized PET surface. As the oxidation degree increased, the contact angle decreased from 137° to 128.90° and 128.50°, suggesting hydrophilicity was enhanced. FTIR and XPS analyses suggested that carbonyl groups increased on the surface of ozonized PET and ozonized-chlorinated PET, while the formation of intermolecular halogen bonds was possible when PET experienced dual oxidation. These physiochemical changes enhanced the adsorption of TBM. The adsorption capacity of TBM followed the order of ozonized-chlorinated PET (2.64 × 10−6 µg/µg) > ozonized PET (2.58 × 10−6 µg/µg) > pristine PET (2.43 × 10−6 µg/µg). The impact of raw water characteristics on the adsorption of TBM onto PETs, such as the pH, and the coexistence of inorganic ions and macromolecules (humic acid, surfactant, and bovine serum albumin) were studied. A different predominant adsorption mechanism between TBM and pristine PET or oxidized PETs was proposed.

Removal of sulfuric acid mist from lead-acid battery plants by coal fly ash-based sorbents.

Sorbents from coal fly ash (CFA) activated by NaOH, CaO and H2O were prepared for H2SO4 mist removal from lead-acid battery plants. The effects of parameters including temperature, time, the ratios of CFA/activator and water/solid during sorbent preparation were investigated. It is found that the synthesized sorbents exhibit much higher removal capacity for H2SO4 mist when compared with that of raw coal fly ash and CaO except for H2O activated sorbent and this sorbent was hence excluded from the study because of its low capacity. The H2SO4 mist removal efficiency increases with the increasing of preparation time length and temperature. In addition, the ratios of CFA/activator and water/solid also impact the removal efficiency, and the optimum preparation conditions are identified as: a water/solid ratio of 10:1 at 120 °C for 10h, a CFA:CaO weight ratio of 10:1, and a NaOH solution concentration of 3 mol/L. The formation of rough surface structure and an increased surface area after NaOH/CaO activation favor the sorption of H2SO4 mist and possible sorption mechanisms might be electrostatic attractions and chemical precipitation between the surface of sorbents and H2SO4 mist.

Enhanced photocatalytic ozonation of organics by g-C3N 4 under visible light irradiation.

Graphitic carbon nitride (g-C3N4) was employed as the active photocatalyst in the photocatalytic ozonation coupling system in the present study. g-C3N4 was prepared by directly heating thiourea in air at 550°C. XRD, FT-IR, UV-vis was used to characterize the structure and optical property. Oxalic acid and bisphenol A were selected as model substances for photocatalytic ozonation reactions to evaluate the catalytic ability of g-C3N4 (g-C3N4/Vis/O3). The results showed that the degradation ratio of oxalic acid with g-C3N4/Vis/O3 was 65.2% higher than the sum of ratio when it was individually decomposed by g-C3N4/Vis and O3. The TOC removal of biphenol A with g-C3N4/Vis/O3 was 2.17 times as great as the sum of the ratio when using g-C3N4/Vis and O3. This improvement was attributed to the enhanced synergistic effect between photocatalysis and ozonation by g-C3N4. Under visible light irradiation, the photo-generated electrons produced on g-C3N4 facilitated the electrons transfer owing to the more negative conduction band potential (-1.3V versus NHE). It meant that the photo-generated electrons could be trapped by ozone and reaction with it more easily. Subsequently, the yield of hydroxyl radicals was improved so as to enhance the organics degradation efficiency. This work indicated that metal-free g-C3N4 could be an excellent catalyst for mineralization of organic compounds in waste control.