PTFE中空纤维膜直接接触式膜蒸馏过程抗污染性能

通过研究不同原水对直接接触式膜蒸馏过程的影响,考察了聚四氟乙烯膜对无机盐、胶体和有机物的抗污染性能。研究表明,在35 g/L氯化钠溶液的4倍浓缩过程中,PTFE膜的相对通量降低至0.72;与碳酸钙饱和溶液的浓缩过程相比,由于溶解度的差异,硫酸钙饱和溶液浓缩过程中晶体析出量更多,通量衰减也更为严重;浓缩硅溶胶时,二氧化硅单体聚合并吸附于膜面从而引起膜通量的衰减,随着浓缩的进行,料液pH值不断上升,使得胶体体系愈加稳定,浓缩到2.6倍后相对通量没有随着浓缩倍数的增加出现明显下降,维持在0.73左右;腐殖酸在水中表现出的亲水性和电负性使其难以在具有较强疏水性的聚四氟乙烯膜表面上形成滤饼层,浓缩过程中相对通量始终保持在0.9以上。

Anti-fouling performance of PTFE hollow fiber membrane through direct contact membrane distillation

To investigate the anti-fouling performance of PTFE hollow fiber membrane in direct contact membrane distillation process, the PTFE membrane was applied to treating different solutions containing inorganic salt, colloid and organic compounds, respectively. The experimental results indicated that the relative flux decreased to 0.72 while NaCl concentration in feed solution rose from 35 g/L to 140 g/L.Owing to the significant differences of water solubility, the flux declined seriously during the concentration process of saturated CaSO4 solution compared with that of saturated CaCO3.A flux decline caused by the deposition of silica on the membrane surface was also observed, and the relative flux could maintain about 0.73 after the concentration factor reached 2.6 because of the enhancement of colloid stability caused by continuous rise of the feed pH. Humic acid was hydrophilic and electronegative when dissolving in water and it was hard to form cake layer on the hydrophobic PTFE membrane surface. During the concentration of humid acid, the relative flux maintained above 0.9.