Fabrication of high boron removal reverse osmosis membrane with broad industrial application prospect by introducing sulfonate groups through a polyvinyl alcohol coating

Abstract

The effective removal of boron from water is highly desirable for many chemical processes. Reverse osmosis (RO) membrane technology has been considered to be a competitive technology for boron removal. However, in addition to seawater, RO membrane technology is rarely used in the treatment of other industrial wastewaters containing boron. In this work, a high boron removal RO membrane with broad industrial application prospect was developed. Specifically, sulfonate groups were grafted onto the surface of the RO membrane through the acetal reaction of polyvinyl alcohol (PVA) with benzaldehyde disulfonic acid disodium salt (BADSA Na). In this process, PVA was coated on the membrane surface in advance. The possibility that large complexes can form due to the reaction between PVA and boric acid and the characteristic of the sulfonate group which can decrease the hydrogen bonding sites work together to reduce the rate of boron diffusion, and then a high boron removal rate is achieved. Under seawater conditions, the boron removal rate of the membrane was improved obviously from 85.71% to 91.63%, while a high flux of 44.41 L m−2 h−1 and a high salt rejection of 99.63% was maintained. In addition, the membranes developed were able to maintain excellent boron removal performance in three other industrial water scenarios (geothermal water, nuclear power plant wastewater and oilfield fracturing flowback fluid). Furthermore, the overall performance of the membrane is better than that of other commercially available membranes and existing processes, showing that the membrane developed has a bright promise for various industrial applications.