摘要
利用小型平板膜测试设备,进行纳滤海水全回流实验研究。考察了操作压力、流量对DL膜通量的影响和膜对海水中主要离子的截留效果,进而研究在7h的运行过程中DL膜对海水的软化效果,最后采用扫描电镜与X射线能谱分析纳滤海水软化过程中微溶盐的结晶情况及二价阳离子与海水中有机物的络合作用。结果表明,荷负电DL纳滤膜具备良好的渗透性和分离性能,膜通量随压力的升高线性增加,提高流量通量略有增大。在0.8～2.4MPa的压力范围内,DL膜对SO42-和Mg2+的截留率分别保持在98%和70%以上,对Ca2+、Na+和Cl-的截留率是随着压力的升高先增大后保持稳定。随着运行时间的延长,膜通量和离子截留率呈现一定下降趋势。在全回流运行方式下,硫酸钙表面结晶是膜通量衰减的主要原因,海水有机物与二价钙镁离子的络合作用甚微。
Using small-scale plate membrane with total recycle mode, the experiments of seawater softening were carried out, and the effects of pressure and flow rate on the performances of DL membrane - the permeate flux and the rejection of ions in seawater were discussed. Furthermore, the softening performances of DL membrane during operation period of 7 h were investigated. Finally, the SEM and EDS analyses were carried out to study the crystallization mode of sparingly soluble salt and the complexation between divalent cations and organic substances in seawater. The results show that the negative-charged DL membrane has excellent permeability and rejection performance, and the flux of the membrane increases linearly with the increase of pressure and increases slightly with the increase of flow rate. As the pressure was increased from 0.8 to 2.4 MPa, the rejections of SO4^2-and Mg^2＋ keep over 98% and 70%, respectively. The other ions, such as Ca^2＋, Na^＋ and Cl^-, increase firstly and then keep steady. During the operation period, both the flux and ions rejections of the membrane decrease with operating time except the rejection for SO4^2-. The SEM and EDS results show that the surface crystallization of calcium sulfate is the main cause of the membrane flux decline, and the effect of complexation of Ca^2＋or Mg^2＋ with nature organic matter （NOM） in seawater is negligible.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2009年第4期582-586,共5页
Journal of Chemical Engineering of Chinese Universities
基金
国家“863”计划项目(2006AA09Z337)
国家自然科学基金项目(20506025)
关键词
纳滤
海水软化
截留性能
膜污染
nanofiltration
seawater softening
rejection performance
membrane fouling
