Search

Highlights: [•] The kinetics of dinoseb chlorination can be described by a second-order model. [•] Dinoseb chlorination is subject to hydroxylation, oxidation and substitution reactions. [•] High concentrations of TCNM and CF were generated and the yields varied with Cl2/C, time and pH. [•] TCNM formation favors acid pHs during dinoseb chlorination. [Copyright &y& Elsevier]

Effective strategies to improve charge separation in semiconductor particles are critical for improving the photodegradation of organic pollutants at levels sufficient for environmental applications. Herein, Bi 2 MoO 6 (BMO MOF ), comprising both nanoparticles (NPs) and quantum dots (QDs), was synthesized from a bismuth-based metal-organic framework (Bi-MOF) precursor. Surface defects on BMO MOF , the combination of NPs and QDs, and modified energy band edges improved photogenerated charge separation and facilitated redox reactions. When compared to BMO derived from uncoordinated Bi, the BMO MOF photocatalyst (PC) was more efficient at photodegrading tetracycline hydrochloride (TCH) and ciprofloxacin (CIP), two widely-used antibiotics ubiquitous in wastewater, as well as the carcinogenic pollutant rhodamine B (RhB). BMO MOF was then loaded on the biopolymer bacterial cellulose (BC) to further enhance photocatalytic performance and facilitate the recovery of the PC after water treatment processes. The novel BMO MOF /BC photocatalytic flakes were significantly larger than pure BMO MOF , and thus easier to recuperate. Furthermore, anchoring BMO MOF on BC flakes augmented significantly the photodegradation of TCH, CIP, and RhB, mainly because hydroxyl groups in BC act as hole traps facilitating photogenerated electron-hole separation. Results obtained with BMO MOF /BC highlight promising approaches to develop optimal PCs for aqueous pollutants degradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

There is growing evidence suggesting the enhancement of brown carbon (BrC) in severe haze episodes. In this study, hourly measurements of BrC in PM 2.5 were conducted in Xi'an, a typical city in northwestern China during winter and summer. The absorption coefficient for methanol exacts at 365 nm (b abs365, methanol , which is typically used as a proxy of methanol-soluble BrC) in the winter sampling period was over 7 times than that in summer. The mass absorption cross-section for methanol extracts (MAC 365, methanol , normalized by b abs365, methanol to organic carbon, OC) in winter sampling period was nearly 1.5 times of that in the summer. During the winter haze days, the average b abs365, methanol peaked at midnight and the lowest values in the morning, in contrast to high levels in afternoon and low levels at night in non haze days. Unlike the diurnal patterns in winter, summer b abs365, methanol diurnal variation presented high midday and low afternoon levels in haze days. However, in non haze days, the pattern showed high morning levels and night low levels. Haze and non haze variations of chemical species levels, b abs365, methanol , and MAC 365, methanol during winter and summer sampling time showed that the effects of atmospheric aging were complex and could either enhance or reduce light absorption of BrC. Source apportionment based on positive matrix factorization receptor model and multiple linear regressions showed that primary emission was an important contributor to BrC emissions during the winter sampling period, whereas secondary formation played an important role in summer., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Domestic solid fuels combustion produces a mass of fine particulate matter (PM 2.5 ). PM 2.5 -bound organics, including polycyclic aromatic hydrocarbons (PAHs), oxygenated-PAHs (OPAHs), phthalate esters (PAEs) and hopanes, were quantified in indoor, outdoor and personal exposure samples collected in rural Guanzhong Basin, China. The average concentration of total quantified PAHs in personal exposure samples was 310 ± 443 ng m -3 , 1.5 times of those of indoor (211 ± 120 ng m -3 ) and outdoor (189 ± 115 ng m -3 ). Similar observations were found for the OPAHs and PAEs, i.e., much higher concentrations were seen in personal exposure samples. Hopanes average personal exposure concentration (13 ± 9.7 ng m -3 ) was comparable to indoors (15 ± 9.7 ng m -3 ) and outdoors (13 ± 9.6 ng m -3 ). Among four common heating ways applied in Chinese dwelling, the highest exposure levels to PAHs, OPAHs and PAEs were found for indoor coal chunks stoves. Concentration under electric power was 1.2-4.5 folds lower than those with solid fuels in this study, proved to be the cleanest energy for the household heating. The exposures to PM 2.5 on cell viabilities were also investigated. The largest reduction of 70% on cell viabilities was seen for indoor coal chunks stove housewives, indicating that the emissions from coal combustion had the greatest cytotoxic effects. The results evidenced that the heating ways in rural area could greatly impact on the housewife health in northwestern China. Advanced heating technology and protection should be conducted to reduce the personal exposures to PM 2.5 from domestic solid fuel combustions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)