膜蒸馏用PDMS/PVDF/PTFE三元共混微孔膜制备

Preparation of PDMS/PVDF/PTFE Ternary Blend Microporous Membranes for Membrane Distillation

采用浸没沉淀相转化法制备了聚二甲基硅氧烷/聚偏氟乙烯/聚四氟乙烯(PDMS/PVDF/PTFE)三元共混微孔膜,并用于20 g/L NaCl水溶液的膜蒸馏脱盐实验。通过扫描电子显微镜观察以及接触角、膜孔隙率和膜平均孔径分析,研究了PTFE含量对膜结构与性能的影响。结果表明,随着PTFE含量的增加,共混微孔膜断面的指状孔逐渐被海绵状取代,平均孔半径由0.234μm增加到0.354μm,膜孔隙率由53.4%增加到81.3%;膜下表面与水接触角从118.52°增加到131.11°;膜蒸馏过程中通量逐渐增加,截留率先稳定后降低,PTFE含量为40%(质量分数,下同)时达最大,为99.99%,此时膜蒸馏通量达16.60 kg/(m^2·h)。

Flat-sheet ternary blend microporous membranes of poly(vinylidene fluoride-cotetrafluoroethylene/dimethylsiloxane) were prepared by the phase inversion process.The desalination behavior of the membrane was tested with a 20 g/L aqueous NaCl solution.The influence of PTFE content on the membrane structure and performance was studied by scanning electron microscope(SEM),contact angle,membrane porosity,and average pore size testing.It was found that finger-like hole at cross-section of the membrane was gradually replaced by a sponge-like structure with increasing PTFE content.The average pore radius was from 0.234 μm to 0.354 μm,and the porosity varied from 53.4% to 81.3%.A contact angle of water droplet on the membrane bottom surface was increased from 118.52 ° to 131.11 °.When the PTFE content was 40 wt%,the permeate flux and rejection were 16.60 kg/(m2 ·h) and 99.99%,respectively.