Utilization of vanillin in modification of polyethersulfone membranes

Abstract

The process streams in the wood-based biorefineries contain a propitious source of novel renewable raw material, such as hemicellulose and lignin. The utilization of UF membranes has been drawn considerable interest in the isolation of hemicellulose from the other dissolved wood components before any further uses. However, membrane filtration processes have been mostly restricted to limited filtration capacities and severe fouling caused by aromatic compounds, such as lignin and extractives. Hence, from an economic point of view, the preparation of competent membranes which can minimize the fouling and life-time shortening of the membranes during filtration are highly demanded. In this study, vanillin as antifouling agent has been utilized in surface modification of commercial ultrafiltration membrane (UH004 P) and in preparation of a novel polyethersulfone ultrafiltration membrane to improve the performance of membrane. The parameters involved in surface modification of UH004 P membrane (e.g. vanillin concentration) and in preparation of PES membrane (e.g. vanillin and water content, and coagulation bath temperature) were investigated. In general, the PEG solution permeability of modified commercial membranes improved as the degree of vanillin adsorption on the surface of the membrane increased while PEG rejection remained almost the same. In addition, better antifouling characteristics of modified membrane compared to virgin UH004 P membrane has been observed; approximately 12 % lower water flux reduction. Based on membrane flux, TOC rejection and UV rejection of lignin, the following conditions for lab-made membrane modification were found to be appropriate: 3 wt.% vanillin content, 1 wt.% water content and coagulation bath temperature of 10 °C.