Highly condensed polyvinyl chloride latex production by forward osmosis: Performance and characteristics

Forward osmosis (FO) has attracted attention in industry because of its low energy consumption and low fouling tendency. In this paper, the condensation of polyvinyl chloride (PVC) latex with FO as a pretreatment step prior to the final drying process was investigated. The effect of agitation speed, FO membrane type, and the NaCl concentration of the draw solution (DS) were evaluated. For the membrane performance, the water flux, NaCl flux, and total organic carbon (TOC) flux were evaluated. When the feed solution was sufficiently agitated, a PVC concentration of 75 wt% was achieved using model sea-water as the DS. FO performance was experimentally compared with reverse osmosis (RO) performance using similar apparatus and the same water flux conditions. The TOC rejection in FO was higher than that in RO. Latex condensation using FO was characterized by a decrease in outlet water flux by cake-enhanced osmotic pressure, a decrease in inlet water flux by the capillary force resistance in the cake layer, and an increase in TOC rejection by the retarded forward diffusion of solutes. The control of cake-layer formation was important for the condensation of PVC latex by FO. (C) 2016 Elsevier B.V. All rights reserved.