Abstract:

A high boron removal reverse osmosis membrane was prepared by modifying the polyamide reverse osmosis membrane by the“swelling-embedding-shrinking”method. Swelling by methanol increases the distance between the polymer chains, providing a place for the embedding of fatty acid (decanoic acid) molecules. Under the action of pressure and concentration polarization, the modified molecules are selectively embedded in the pores of the polyamide membrane. When the methanol molecules leave, the polyamide membrane shrinks to immobilize the decanoic acid molecules in the polymer network. This experiment increases the boron removal rate of the reverse osmosis membrane by increasing steric hindrance and reducing polarity (reducing hydrogen bonding sites). The experimental results show that the boron removal rate and the salt rejection rate of the modified membrane are both increased. The salt rejection rate is increased from 90.36% to 96.46%, and the boron removal rate is increased from 47.85% to 77.32%. In addition, the boron concentration in the permeate is less than 2.4 mg/L to meet emission standards (WTO). Although the permeability of water and boron decreased, the permeability selectivity of water and boron increased, which proves that the method is advantageous for increasing the selectivity of water and boron.

Key words: boron removal, membrane, swelling-embedding-shrinking, separation, mass transfer, alcohol

摘要：

采用“溶胀-嵌入-收缩”方法改性聚酰胺反渗透膜，制备了一种高脱硼反渗透膜。通过甲醇溶胀增加了高分子链之间的距离，为疏水性癸酸分子的嵌入提供了场所，然后在压力和浓差极化共同作用下，改性分子选择性嵌入聚酰胺膜的孔内；当甲醇分子离开后，聚酰胺膜收缩将癸酸分子固定在高分子网络中。实验借助溶胀和分子嵌入以及溶胀后的收缩调节聚酰胺膜的孔径大小；利用脂肪酸的疏水性降低聚酰胺膜的极性，从而实现增加空间位阻和减少氢键结合位点数量的目的。实验结果显示，改性膜的脱硼率和截盐率均明显升高，截盐率从90.36%增加到96.46%，脱硼率从未改性膜的47.85%增加到77.32%，渗透液的硼含量达到WTO的使用标准。虽然水和硼的渗透性均下降，但是水和硼的渗透选择性增加，证明该方法有利于提高水硼选择性。

关键词: 脱硼, 膜, 溶胀-嵌入-收缩, 分离, 传质, 醇