聚偏氟乙烯膜亲水改性及其乳液分离与重金属吸附应用

聚偏氟乙烯（PVDF）膜因其优异的化学和力学稳定性而被广泛应用于水处理领域，但PVDF膜本身的疏水性，容易使其在处理含油废水的过程中被油滴污染，造成膜孔堵塞。以PVDF微滤膜为基底，通过单宁酸（TA）和聚乙烯亚胺（PEI）共沉积形成了TA/PEI黏附层，经戊二醛共价交联和接枝半胱氨酸（Cys），制备了一种PVDF改性膜（PVDF@TA/PEI-Cys）。改性后的PVDF膜具有良好的亲水性和水下超疏油性，水接触角和水下油接触角分别为22.2°和150.2°。在0.09 MPa下，PVDF@TA/PEI-Cys膜的纯水通量达6328 L/（m²·h），水包油型乳液分离效率高达99.9%。此外，该改性膜还可同时吸附水中的汞离子，最大吸附量为24.7 mg/g。

Preparation of hydrophilic poly(vinylidene fluoride) membrane for oil/water emulsion separation and heavy metal ions adsorption

Polyvinylidene fluoride (PVDF) membrane is widely used in the field of wastewater treatment due to its excellent chemical and mechanical stability. However, the hydrophobicity of the PVDF membrane makes it easy to be contaminated by oil droplets during the treatment of oily wastewater, which causes the pores of the membrane to be blocked and the decrease in permeation flux. In this study, we developed an approach for preparing a hydrophilic PVDF membrane. Specially, the co-deposition of tannic acid (TA) and polyethyleneimine (PEI) on the PVDF membrane was conducted for the formation of TA/PEI adhesive layer, which was covalently grafted with cysteine via glutaraldehyde to fabricate a modified PVDF membrane (PVDF@TA/PEI-Cys). The PVDF@TA/PEI-Cys membrane has good hydrophilicity and underwater superoleophobicity. The water contact angle and underwater oil contact angle were 22.2° and 150.2°, respectively. The pure water flux of the PVDF@TA/PEI-Cys membrane reached 6328 L/(m²·h) under 0.09 MPa and the separation efficiency of the oil-in-water emulsions was as high as 99.9%. In addition, the modified PVDF membrane can also be used for the adsorption of mercury ions with the maximum adsorption capacity of 24.7 mg/g.