State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
Chemosphere. 2022 Apr;292:133444. doi: 10.1016/j.chemosphere.2021.133444. Epub 2021 Dec 29.
Chemicals soaking is generally acknowledged as a convenient and efficient method to improve the performance of reverse osmosis (RO) membranes. The conventional soaking of RO membranes in alkaline sodium hypochlorite (NaClO) usually promotes extensive hydrolysis and cleavage amide bonds, resulting in improved water flux but declined salt rejection. Here, alcohols were added into the NaClO solution to regulate the chlorination processes using their "swelling-fastening" effect. The alcohols could interact with polyamide chains, and thus swell the polyamide network. Due to this interaction, the NaClO has less probability of attacking the polyamide chains. Hence, the chlorine-promoted hydrolysis was partly eased, which could weaken the decrease of salt rejection. Besides, after removing alcohols as well as the dissolved small oligomers and fragments of polyamide, the network was compacted and the loosened sites were healed, which is also beneficial to increase the difficulty of salt penetration. The treatment of RO membrane by the NaClO and alcohols could produce a hydrophilic surface with increased water flux and high salt rejection. The membrane chloridized at 2000 ppm NaClO exhibited a water flux improvement of 20.28% and a salt rejection declination of 0.95%. When treated with 2000 ppm NaClO associated with 5% methanol, the water flux improved 20.13% with little declination in salt rejection.
化学浸泡通常被认为是一种方便且高效的方法，可以提高反渗透（RO）膜的性能。传统的 RO 膜在碱性次氯酸钠（NaClO）中的浸泡通常会促进广泛的水解和酰胺键的断裂，从而提高水通量，但降低盐的截留率。在这里，添加醇到 NaClO 溶液中，利用其“溶胀-紧固”效应来调节氯化过程。醇可以与聚酰胺链相互作用，从而使聚酰胺网络溶胀。由于这种相互作用，NaClO 攻击聚酰胺链的可能性降低。因此，氯促进的水解部分缓解，这可以减弱盐截留率的降低。此外，在去除醇以及溶解的小低聚物和聚酰胺片段后，网络变得更加紧凑，松散的部位得到修复，这也有利于增加盐渗透的难度。RO 膜经 NaClO 和醇处理后，可以产生具有高水通量和高盐截留率的亲水表面。在 2000ppmNaClO 下氯化的膜水通量提高了 20.28%，盐截留率下降了 0.95%。当用 2000ppmNaClO 与 5%甲醇处理时，水通量提高了 20.13%，盐截留率几乎没有下降。
