膜科学与技术

SAXS技术表征氯解复合反渗透膜结构演变

作者：王剑，魏杨扬，田欣霞，张潇泰，赵曼，张慧峰

单位：自然资源部天津海水淡化与综合利用研究所，天津 300192

关键词：小角X射线散射，聚酰胺反渗透膜，氯解，结构演变

出版年,卷(期):页码： 2020,40(6):96-103

摘要：

目前主要从化学组成角度阐述反渗透膜氯化机理，氯化导致的微观结构变化及其对水盐分离性能的影响缺乏有效的表征手段。采用小角X射线散射（SAXS）技术表征不同氯化强度处理的反渗透膜，研究分离层微观结构参数旋转半径（Rg）、相关距离（a）和分形维数（β）与水透过系数（A）和盐透过系数（B）的关系。结果表明，随着氯化强度的增加，聚酰胺分离层的Rg、a和β单调增加，且与A的变化正相关，相关系数（R2）高达0.99；长程相关距离a2（R2=0.9915）与A的相关性高于短程相关距离a1（R2=0.8781），说明氯化作用对二级结构粒子（对应a2）的破坏作用大于对初级结构粒子（对应a1）的破坏作用；B与Rg、a和β的线性相关性较弱，分别为0.8155（Rg）、0.9148（a1）、0.7801（a2）、0.7621（β），是因为B还受荷电性等因素的影响。

Reported mechanistic chlorination analysis of polyamide (PA) reverse osmosis membranes heavily relies on the change of chemical element composition under different chlorination dosage. It still lacks the effective technique to characterize the evolution of PA membrane microstructure, and its nexus with water permeability and/or water/salt selectivity. Herein, small angle x-ray scattering (SAXS) technique was adopted to investigate the microstructure evolution of PA reverse osmosis membrane exposed in sodium hypochlorite. Structure parameters including radius of gyration (Rg), correlation distance (a) and fractal dimension (β) were analyzed, and their relationship between water permeation coefficient (A) and NaCl permeation coefficient (B) were investigated. The results indicated that Rg, a and β monotonically increased with the intensity of chlorination, and were positively correlated with A, giving a correlation coefficient (R2) of ~ 0.99. The correlation between the A and long-range correlation distance (a2) gave a higher R2 (0.9915 vs 0.8781) when compared with the short-range correlation distance (a1), indicating that the destructive effect for the secondary structure particle (corresponding to a2) is more severity. There were weak correlations between the B and the structure parameters, R2 of 0.8155 (Rg), 0.9148 (a1), 0.7801(a2) and 0.7621 (β), which is due to the impact of charge performance.

王剑（1985-），男，山东潍坊人，博士，从事反渗透和纳滤膜材料的开发研究，E-mail：wangjian_isdmu@163.com

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