Tan Qiyin, Shen Yue, Sun Jiahao, Jian Tao, Lu Wen, Wu Sijin, Zhao Zengjian, Lei Qian, Lin Hongjun
College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China; Key Laboratory of Watershed Earth Surface Processes and Ecological Security, Zhejiang Normal University, Jinhua 321004, China.
College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China; Key Laboratory of Watershed Earth Surface Processes and Ecological Security, Zhejiang Normal University, Jinhua 321004, China.
Sci Total Environ. 2024 Nov 15;951:175775. doi: 10.1016/j.scitotenv.2024.175775. Epub 2024 Aug 26.
Organics and divalent cations are the primary barriers constraining the performance of membrane technology, while the interactions between them and the detailed mechanisms of their impacts are still lacking in-depth analysis. In this study, sodium alginate and xanthan gum were selected as polysaccharides models, and the formation of transparent extracellular polymer particles (TEP) was assessed to examine the effect of Ca and polysaccharides type on membrane fouling from both qualitative and quantitative perspectives. The results revealed that higher Ca concentrations led to a greater abundance of TEP, and the transformation of TEP microstructure is a key factor for the membrane fouling change indicated by specific filtration resistance (SFR). TEP formed by sodium alginate underwent a transformation from amorphous-TEP (a-TEP) form to particle-TEP (p-TEP), corresponding to a unimodal pattern of SFR variation. With increasing Ca concentration, the molecular interactions of xanthan gum became stronger, resulting in larger fibrous a-TEP and a continuous SFR increase. According to the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, TEP formed by xanthan gum exhibited higher adhesion energy, thus causing more severe membrane fouling. The SFR variation of the TEP system can be satisfactorily explained by the conception of chemical potential change in the filtration process depicted in Flory-Huggins theory. This study is the first work to introduce models regarding chemical potential and TEP microstructure, linking the system chemical potential and TEP microstructure with membrane fouling indicated by SFR. As all, this study provided a new perspective for analyzing the polysaccharide fouling behavior via TEP determination and further enhanced the understanding through thermodynamic analysis.
有机物和二价阳离子是制约膜技术性能的主要障碍，然而它们之间的相互作用及其影响的详细机制仍缺乏深入分析。本研究选择海藻酸钠和黄原胶作为多糖模型，通过评估透明胞外聚合物颗粒（TEP）的形成，从定性和定量两个角度考察钙和多糖类型对膜污染的影响。结果表明，较高的钙浓度导致TEP丰度更高，TEP微观结构的转变是由比过滤阻力（SFR）表示的膜污染变化的关键因素。由海藻酸钠形成的TEP经历了从无定形TEP（a-TEP）形式到颗粒状TEP（p-TEP）的转变，对应于SFR变化的单峰模式。随着钙浓度的增加，黄原胶的分子间相互作用增强，导致形成更大的纤维状a-TEP，SFR持续增加。根据扩展的Derjaguin-Landau-Verwey-Overbeek（XDLVO）理论，由黄原胶形成的TEP表现出更高的粘附能，从而导致更严重的膜污染。TEP系统的SFR变化可以用Flory-Huggins理论中描述的过滤过程中化学势变化的概念来令人满意地解释。本研究首次引入了关于化学势和TEP微观结构的模型，将系统化学势和TEP微观结构与由SFR表示的膜污染联系起来。总之，本研究为通过TEP测定分析多糖污染行为提供了新的视角，并通过热力学分析进一步加深了理解。
