Performance optimization of diamine cross-linked mixed matrix membrane for high value organic acid recovery

Abstract

A modelling and optimization approach was implemented for the succinate recovery, a high-value organic acid, from concentrated feeds using polyimide (PI)/graphene oxide (GO) mixed matrix membrane (MMM) cross-linked with ethylenediamine (EDA). The effects of parameters, including i) time for crosslinking, ii) time for solvent evaporation, and iii) feed concentration, on succinate rejection and separation factor (SF) were investigated. The optimization of the dominant factors, namely, crosslinking time and succinate concentration, greatly enhanced the succinate rejection and SF, where 73% initial drop in succinate rejection was improved, and a membrane rejection performance of above 80% was sustained, even when the succinate concentration rose to 50 g/L. This improvement was attributed to the formation of covalent bonds and a reduction in the d-spacing of the cross-linked MMM. The optimization study with a desirability of 0.81 also demonstrated the applicability of the model to an actual broth. The optimized membrane prepared at 1.61 h crosslinking time, 30 s evaporation time and 30 g/L succinate concentration demonstrated 86% succinate recovery from the actual broth, 0.15-0.33 SF, and 96% flux recovery ratio. Thus, this optimization study could be a way forward in exploring, simultaneously expanding cross-linked membrane applications especially in product recoveries from concentrated feed(s).