Synthesis of asymmetrical cellulose acetate/cellulose triacetate forward osmosis membrane: Optimization

This study aims at identifying asymmetric cellulose acetate (CA)/cellulose triacetate (CTA) forward osmosis (FO) membranes that have high water flux (J(v)) and low reverse salt diffusion flux (J(s)) with acetic acid to replace the 1,4-dioxane for the mixed solvent for CA/CTA dissolution. The optimum fabrication parameters for the CA/CTA FO membranes are determined by using response surface methodology with a 4(3) Box-Behnken design. Effects of weight fraction of CA (at CA/CTA = 2), spinning speed, annealing temperature and annealing time on the J(v) and J(s) are investigated. The optimum conditions to maximize the J(v) to 6.4 L/m(2)/h and minimize J(s) to 0.47 g/m(2)/h together are: 6%/3% CA/CTA, 2993 rpm spinning speed, 87.8 degrees C annealing temperature and 180s annealing time. The fabricated FO membranes can reject over 99.9% heavy metal ions from feed wastewater and can be used as an effective barrier for alginate gels with easy flux recovery by ultrasound cleaning. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.