Comparative Degradation Kinetics Study of Polyamide Thin Films in Aqueous Solutions of Chlorine and Peracetic Acid Using Quartz Crystal Microbalance
Comparative Degradation Kinetics Study of Polyamide Thin Films in Aqueous Solutions of Chlorine and Peracetic Acid Using Quartz Crystal Microbalance
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DOI：
10.1021/acs.langmuir.1c02835
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发表时间：
2021-12-07
期刊：
影响因子：
3.9
通讯作者：
Nalam, Prathima C.
中科院分区：
文献类型：
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作者：
Mohona, Tashfia M.;Dai, Ning;Nalam, Prathima C.
聚酰胺薄膜复合膜广泛应用于水回收。过氧乙酸（PAA）是一种新兴的废水消毒剂，具有清洁和消毒膜的潜力。然而，它与聚酰胺的相互作用仍然知之甚少。本研究采用石英晶体耗散微天平（QCM-D）测定paa诱导聚酰胺薄膜的降解动力学，并与传统的无消毒剂氯（HOCl）进行比较。当聚酰胺膜暴露于PAA （1000 mg L-1）和HOCl （100 mg L-1）溶液时，表现为吸附期和降解期。HOCl实验的吸附期较短（1.4 ~ 3.5 min），为玻尔兹曼-s型模型，而PAA实验的吸附期为3 ~ 33 h，为两阶段行为。后一种动力学归因于PAA在聚酰胺薄膜中的物理吸附，然后是PAA诱导的聚酰胺氧化的顺序过程。在降解阶段，hocl暴露的薄膜经历了快速的两步指数衰减，在大约5小时的暴露后达到了接近初始（湿）质量50%的平衡质量。相比之下，paa暴露的薄膜呈现玻尔兹曼-s型衰减，在暴露bb10小时后，大约80%的初始（湿）质量保持完整。原子力显微镜生成的快速力图显示，在流动和无流动条件下，聚酰胺膜在HOCl溶液中由于点蚀、开裂、胀形和最终的分层而逐渐增加了形态不均匀性。相比之下，PAA在流动状态下仅在聚酰胺膜上形成小凹坑；在停滞的PAA溶液中，胶片在大约148小时的曝光后也没有明显的变化。这是首次比较PAA和HOCl对聚酰胺膜的化学和形态变化的研究。聚酰胺与PAA的相容性比与氯的相容性高得多，这支持了PAA作为无卤膜清洁/消毒剂的潜力。
Polyamide thin film composite membranes are widely used in water reclamation. Peracetic acid (PAA) is an emerging wastewater disinfectant with a potential for membrane cleaning and disinfection; however, its interaction with polyamide remains poorly understood. This study employs quartz crystal microbalance with dissipation (QCM-D) to determine the PAA-induced degradation kinetics of polyamide thin films, in comparison with the conventional disinfectant-free chlorine (HOCl). Polyamide films showed a sorption phase followed by a degradation phase when exposed to PAA (1000 mg L-1) and HOCl (100 mg L-1) solutions. While the sorption phase in HOCl experiments was short (1.4-3.5 min) and followed a Boltzmann-sigmoidal model, it spanned over 3-33 h in PAA experiments and displayed a two-stage behavior. The latter kinetics are attributed to sequential processes of the physical sorption of PAA in polyamide films followed by PAA-induced polyamide oxidation. In the degradation phase, the HOCl-exposed films followed a rapid, two-step exponential decay reaching an equilibrium mass of similar to 50% of the initial (wet) mass after similar to 5 h of exposure. In contrast, the PAA-exposed films followed a Boltzmann-sigmoidal decay, with similar to 80% of the initial (wet) mass remaining intact after >10 h of exposure. Fast force maps generated using atomic force microscopy showed a progressive increase in the morphological heterogeneity of the polyamide films in HOCl solution due to pitting, cracking, bulging, and eventual delamination under both flow and no-flow conditions. In contrast, PAA only formed small pits on the polyamide film under flow; in a stagnant PAA solution, the film had no visible changes even after similar to 148 h of exposure. This is the first comparative study on the chemical and morphological changes in polyamide films induced by PAA and HOCl. The much higher compatibility of polyamide with PAA than with chlorine supports the potential of PAA being used as a halogen-free membrane cleaning/disinfecting agent.