Enhanced removal of methylparaben mediated by cobalt/carbon nanotubes (Co/CNTs) activated peroxymonosulfate in chloride-containing water: Reaction kinetics, mechanisms and pathways
| Autor: | Hang Dong, Guoguang Liu, Bingjie Wang, Zhimin Gong, Yaozong Zhang, Haijin Liu, Jialu Shi, Shixiang Gao, Jianbiao Peng, Mengjie Wang, Shiyin Wang, Zhexi Wang, Guangxuan Yan, Jin Liu, Zhiguo Cao |
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| Rok vydání: | 2021 |
| Předmět: |
Methylparaben
General Chemical Engineering chemistry.chemical_element 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Hydrogen atom abstraction 01 natural sciences Chloride Industrial and Manufacturing Engineering Coupling reaction 0104 chemical sciences Catalysis Chemical kinetics chemistry.chemical_compound Reaction rate constant chemistry medicine Environmental Chemistry 0210 nano-technology Cobalt Nuclear chemistry medicine.drug |
| Zdroj: | Chemical Engineering Journal. 409:128176 |
| ISSN: | 1385-8947 |
| Popis: | Chloride ion (Cl−) widely presents in natural water and wastewater, which can significantly affect the performance of sulfate radical-based advanced oxidation processes (SR-AOPs). However, few studies are available now on the generation of chlorinated by-products in the peroxymonosulfate (PMS) based systems. Here a novel catalyst (cobalt/carbon nanotubes, Co/CNTs) was synthesized and used as a PMS activator to remove methylparaben (MeP) with and without Cl−. The morphology and chemical composition of the fresh and used Co/CNTs were characterized by TEM, SEM, XRD, BET, and XPS. Results revealed that Co/CNTs exhibited significant catalytic activity toward MeP removal, and the removal efficiency increased with the augment of reaction temperature and concentrations of Co/CNTs and PMS. In the absence of Cl−, 83.2% of 10 μM MeP was degraded within 60 min by using 2 mg/L Co/CNTs and 100 μM PMS at 25 °C with pH 7.0. However, complete removal of MeP was achieved within 20 min in the presence of 100 mM Cl−, which enhanced the apparent rate constant by a factor of 4.3. Consequently, TOC removal was enhanced from 8.1% to 19.2% within 60 min. Through the quenching experiments, both SO4 − and OH were found responsible for MeP degradation without Cl−, while Cl2− was the main reactive oxygen species (ROS) with 100 mM Cl−. Based on the intermediates identified via TOF-LC-MS, four potential reaction pathways were proposed, including hydrogen abstraction coupling reaction, hydroxylation, OH attack, and Cl2− attack. The intermediates also exhibited decreased toxicity compared to the parent compound based on the ecotoxicity evaluation. In addition, Co/CNTs + PMS system achieved over 60% MeP removal from real wastewater with elevated PMS concentration, indicating the process applicability. These findings provide valuable information of SR-AOPs to facilitate organic contaminants removal in Cl−-containing water. |
| Databáze: | OpenAIRE |
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