Highly Permeable Double-Skinned Forward Osmosis Membranes for

Article pubs.acs.org/est

Highly Permeable Double-Skinned Forward Osmosis Membranes for Anti-Fouling in the Emulsified Oil−Water Separation Process Phuoc H. H. Duong,† Tai-Shung Chung,†,‡,* Shawn Wei,§ and Lana Irish§ †

Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore ‡ Water Desalination & Reuse (WDR) Center, King Abdullah University of Science and Technology, Saudi Arabia 23955-6900 § Kraton Polymers, LLC., 15710 John F. Kennedy Boulevard, Suite 300, Houston, Texas 77032, United States S Supporting Information *

ABSTRACT: Forward osmosis (FO) has attracted wide attention in recent years. However, the FO performance may be restricted due to internal concentration polarization (ICP) and fast fouling propensity that occurs in the membrane sublayer. Particularly, these problems significantly affect the membrane performance when treating highly contaminated oily wastewater. Recently, double-skinned flat sheet cellulose acetate (CA) membranes consisting of two selective skins via the phase inversion method have demonstrated less ICP and fouling propensity over typical single-skinned membranes. However, these membranes exhibit low water fluxes of 150 μm), dispersed oil (20 μm < oil droplet size < 150 μm) and emulsified oil (oil droplet size 99.9 >99.9

single-skinned (TFC) memebrane double-skinned (TFC and Nexar copolymer) membrane a

Tested at 5 bar using DI water as the feed. bTested at 5 bar using 2000 ppm NaCl as the feed. cTested at 5 bar using 200,000 ppm oil−water emulsion as the feed.

Table 2. Performance of the Single-Skinned Membrane and the Double-Skinned Membrane membranes single-skinned (TFC) memebrane double-skinned (TFC and Nexar copolymer) membranea

membranes orientation (mode)

water fluxb, Jv (LMH)

reverse salt fluxb, Js (gMH)

AL-FS (FO) AL-DS (PRO) AL-DS (PRO)

12.8 18.5 17.2

3.43 5.25 4.85

oil fluxc, Jo (gMH)

feed

draw solution

DI water

0.5 M NaCl single-skinned (TFC) memebrane

double-skinned (TFC and Nexar copolymer) membranea

AL-FS (FO) AL-DS (PRO)

9.1 11.4