PREPARATION AND CHARACTERIZATION OF POLYACRYLONITRILE/BENTONITE BLEND MEMBRANE FOR WASTEWATER TREATMENT

摘要

In this study, bentonite nanoparticles with different dosages were incorporated into polyacrylonitrile (PAN) matrix for modification via the non-solvent induced phase separation (NIPS) method. The effect of nano-bentonite particles concentration in the casting solution on the membrane physicochemical characteristics was investigated. A series of tests, such as field emission scanning electron microscopy (FESEM) analysis, pure water flux, contact angle (CA), zeta potential and membrane fouling rate tests were used to characterize membrane performance. It was found that the addition of nano-bentonite particles could improve the membrane performance effectively. The membrane surface pore morphologies changed little with the addition of nano-bentonite and the mean pore size and surface porosity of the PAN membranes were increased with the addition of nano-bentonite 0.05-0.2 wt%. Moreover, the addition of nano-bentonite particles could improve the membrane permeability. Certain amount of nano-bentonite additive was able to enhance the membrane surface hydrophilicity and made the modified membrane surface charge more negative while excessive addition could not improve the membrane performance. Additionally, the amount of 0.05 wt% was deemed to be optimal in terms of membrane fouling because this membrane showed the lowest fouling rate in a membrane bioreactor (MBR). Soluble microbial products (SMP) of MBR was fractionated into four components and introduced to filter the virgin membrane and the modified membrane to understand the mechanism of fouling mitigation. The membrane anti-fouling performance for the charged hydrophilic (HPI-C) fraction of modified membrane was substantially enhanced due to the negatively charged surface which was the main reason of the fouling mitigation compared with the virgin membrane.