文献类型：期刊文献

英文题名：New Insights to Chlorination-Induced Chemical Bond Cleavage in Polyamide Membranes: Degradation Mechanisms and the Role of Calcium and Magnesium Ions

作者：Yu, Qinyu[1]; Wu, Shuang[2]; Yang, Linyan[1,3,4]; Chen, Xueming[5]; Tao, Min[1]; Wu, Yi[1]; He, Xiaowei[1]; Bai, Lichun[2]; Meng, Shujuan[6]

机构：[1] School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China; [2] Key Laboratory of Traffic Safety on Track, Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, 410075, China; [3] Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China; [4] National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, East China University of Science and Technology, Shanghai, 200237, China; [5] College of Environment and Safety Engineering, Fuzhou University, Fuzhou, 350116, China; [6] School of Space and Environment, Beihang University, Beijing, 100191, China

年份：2024

外文期刊名：SSRN

收录：EI(收录号：20240411403)

语种：英文

外文关键词：Biofiltration - Biogeochemistry - Chlorination - Coordination reactions - Degradation - Hydrogen bonds - Microfiltration - Nafion membranes - pH - Spectroscopic analysis - Water filtration

摘要：This study aims to formulate the degradation mechanism of polyamide membrane by chlorine, and to assess the role of Ca2? or Mg2? involved in chlorination. By adjusting chlorination pH, two competing degradation mechanisms, namely chlorination-promoted hydrogen bond cleavage and chlorination-promoted hydrolysis, were first time proposed. Hydrogen bond cleavage promoted severe compaction (reduced pore radius), while hydrolysis led to a loose but non-compactable structure (increased pore radius), causing opposite trends in membrane filtration performance at different pHs. The pore radius and water flux were reduced by 33% and 69% at chlorination pH 4.0, however, water flux was increased by 45% at chlorination pH 10.0. Therefore, intermolecular rather than intramolecular bonds regulate the rotational freedom and then affect compactness of polyamide layers under pressure. Ca2? or Mg2? further amplified these effects of chlorine, i.e., water flux was further reduced by 7%-10% at pH 4.0 and further increased by 23%-48% at pH 7.0-10.0. The coordination between carbonyl oxygen and Ca2? or Mg2?, verified by simulated molecular electrostatic potential and binding energies, initiated excessive hydrogen bond breakage between C=O and N?H and thereby prompted N-chlorination, owing to the higher chlorination priority of non-hydrogen-bonded over hydrogen-bonded N?H. In addition, Ca2? or Mg2? accelerated chlorination-promoted hydrolysis. ? 2024, The Authors. All rights reserved.