| XDLVO理论解析不同离子条件下海藻酸钠微滤膜污染 |
| 摘要点击 3098 全文点击 1644 投稿时间：2013-08-30 修订日期：2013-11-01 |
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| 中文关键词 XDLVO理论 界面微距相互作用 微滤膜 海藻酸钠 离子组成 |
| 英文关键词 XDLVO theory short-range interfacial interactions MF membrane sodium alginate(SA) ionic composition |
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| 中文摘要 |
| 应用extended Derjaguin-Laudau-Verwey-Overbeek （XDLVO） 理论定量解析海藻酸钠微滤膜污染中界面微距作用力，探讨不同离子条件对膜污染影响的主控机制.结果表明，对于亲水性膜表面，范德华力促进膜污染，极性作用力阻碍膜污染；而对于疏水性膜表面，范德华力减缓膜污染，极性作用力加速膜污染.海藻酸钠与微滤膜接触时双电层作用力对膜污染贡献相对微弱.离子强度及钙离子对海藻酸钠微滤膜污染的影响主要是通过改变极性作用力来实现的.较高的离子强度会降低极性作用力的排斥性或升高极性作用力的吸引性，从而加重海藻酸钠微滤膜污染.虽然钙离子使出水通量急速下降，但钙离子的存在使得物理清洗效率提高.不同离子条件下初始阶段及后期阶段污染趋势K分别与膜-海藻酸钠粘附自由能及海藻酸钠-海藻酸钠粘聚自由能具有良好的线性相关性，表明XDLVO理论适用于描述不同离子条件下海藻酸钠微滤膜污染行为. |
| 英文摘要 |
| The extended Derjaguin-Laudau-Verwey-Overbeek (XDLVO) theory was utilized to quantitatively evaluate short-range interfacial interactions involved in microfiltration (MF) membrane fouling by sodium alginate (SA) at various ionic compositions. Results showed that for hydrophilic membrane surfaces, van der Waals interactions facilitated fouling, whereas acid-base interactions alleviated fouling; for hydrophobic membrane surfaces, however, van der Waals interactions mitigated fouling and acid-base interactions turned out to be favorable for fouling. Electrostatic double layer interactions contributed minimally to fouling when SA molecules came into contact with MF membrane surface. Ionic strength and Ca2+ affected SA fouling of MF membranes mainly through alteration of acid-base interactions between membrane and SA or among SA themselves. Higher ionic strength could make acid-base interaction less repulsive or more attractive, thus aggravating SA fouling of MF membrane. Although Ca2+ accelerated flux decline significantly, Ca2+ could enhance physical cleaning efficiencies. Under all tested ionic compositions, fouling potentials (K) of initial and subsequent stages correlated well with membrane-SA interfacial free energy of adhesion and SA-SA interfacial free energy of cohesion, respectively. This implies that the XDLVO theory is applicable for description of MF membrane fouling by SA at various ionic compositions. |
