Desalination characteristics of TFN-RO membrane incorporated with ZIF-8 nanoparticles

Abstract

Nanoparticle addition to membranes is advancing the performance of separation processes and improving the flux without jeopardizing the selectivity. However, fouling-resistance improvement of RO membranes is still needed in the desalination industry. The objective of this paper is to investigate the addition of ZIF-8 to the membrane selective-layer and its effect on the improvement of membrane fouling-resistance. SEM images of ZIF-8 nanoparticle showed a rhombic dodecahedral shape with an apparent uniform size of around 80nm and BET surface area of 735m2/g while membrane images showed a typical ridge and valley structure of aromatic polyamide (PA). The contact angle of the best performing membrane PZ4 (33.2°) was much lower than that of the control membrane (62.8°) suggesting higher surface-hydrophilicity. The permeate flux of PZ4 increased 53% compared to the control PA membrane under brackish water conditions while maintaining high salt rejection of 99.4%. Under fouling conditions with BSA, the control PA membrane lost more than 50% of its initial flux while PZ4 lost only 13% after 4h of continuous operation. This study showed that ZIF-8 nanoparticles can significantly enhance the polyamide fouling-resistance and in the case of PZ4 membrane, the fouling was remarkably reduced by more than 75%.