纳米TiO2Al2O3改性PVDF膜对APAM吸附污染机理及研究.docVIP

纳米TiO2/Al2O3改性PVDF膜对APAM的吸附污染机理研究 摘要：研究了改性PVDF膜对阴离子型高分子聚丙烯酰胺(APAM, 688万)的吸附等温线、吸附热力学及动力学特征;以此为基础建立了超滤过程中吸附污染引起的通量衰减模型并检验;最后采用扫描电镜(SEM)、傅里叶变换红外光谱(ATR-FTIR)等对膜结构考察.结果表明:APAM在超滤膜上的吸附等温线符合Langmuir-Freundlich吸附模型,该过程为非自发的吸热吸附过程;吸附平衡时间约为8h,满足伪一级动力学模型;通量衰减模型能很好的模拟不同条件下因吸附污染引起的通量衰减过程.此外,通过微观分析可知,该吸附过程驱动力主要由膜的微孔结构提供;此外,纳米颗粒的加入促进了膜片对APAM吸附能力的提高.本研究可为分析认识PVDF超滤膜对荷负电聚电解质的吸附污染机理提供一定的理论依据. 关键词：纳米TiO2/Al2O3; PVDF超滤膜; 阴离子聚丙烯酰胺；吸附机理；数学模型 Mechanisms of APAM adsorption by TiO2/Al2O3 Modified PVDF UF membrane and flux decline prediction Abstract: The mechanisms of high-molecular-weight anionic polyacrylamide (APAM,6880KDa) adsorption onto modified PVDF membrane (MM) were investigated via analysis of adsorption isotherms, thermodynamics and kinetics; Flux attenuation model based on adsorption was established and tested; at last, the process was explored by SEM and ATR-FTIR.The results show that: the adsorption isotherm suite to the Langmuir - Freundlich adsorption model, and the process is a non-spontaneous, endothermic adsorption process with an equilibrium time of about 8h, which abided by pseudo-first order kinetics model; flux attenuationthe model can be well simulated the flux change under different conditions due to adsorption pollution caused. In addition, microscopic analysis indicates that adsorption was driven by porous structure adsorption, while nano-particles could be another important factor for its’ physical and chemical interactions with APAM. Keywords: nano-sized TiO2/Al2O3; anion polyacrylamide; PVDF UF membrane; adsorption mechanism; Mathematic model 近年来,以聚合物驱油为代表的三次驱油技术已成为我国油田开发的主流技术[1],其中,水溶性聚电解质,如阴离子型聚丙烯酰胺(APAM)的加入可提高驱替液的粘度,增大波及效率,大大提高石油采出率.同时,每年约5000万吨的油田采出水产生,聚合物(＞100mg/L)、乳化油、悬浮颗粒等的残留导致废水粘度增加,乳化程度加大,增加了处理的难度[2].当前,油田采出水的处理方法主要有:重力沉降分离,容器气浮分离,超声破乳,混凝/凝聚,生物法等[3,4],然而,这些方法处理效率低,处理成本高,二次污染严重[5]. 超滤(UF)技术被认为是最为灵活的分离技术,深受研究者的重视.近年来,超滤技术成功应用于乳化油,牛血清蛋白等领域的报道层出不穷[6,7],但有关聚电解质类物质的膜法处理技术却鲜有报道,且膜污染问题也常常成为限制膜技术应用的主要障碍.对疏水性有机物而言,膜表面亲水性的增加可在一定程度上减缓其污染.然而,对亲水性有机物却并非如此.因此,本文旨在通