Industrial & Engineering Chemistry Research, Vol.54, No.23, 6067-6074, 2015
Innovation in Draw Solute for Practical Zero Salt Reverse in Forward Osmosis Desalination
In forward osmosis (FO), reverse salt diffusion not only reduces water flux but also increases the requirement of draw solute replenishment. FO would be very desirable if there was no draw solute leakage and the recovery of draw solutes was easy. In this study, a novel draw solute, ethylenediaminetetraacetic acid (EDTA)-2Na coupled with Triton X-100 was explored with the aim of minimizing reverse salt diffusion. The results indicated that reverse salt diffusion achieved zero the first time when using 0.1 M EDTA-2Na coupled with 0.5 mM Triton X-100 as draw solution and DI water as feed solution. A water flux of 4.6 L/m(2) h was reached when 35 g/L NaCl of model seawater was used as the feed solution and 1 M EDTA-2Na coupled with 0.5 mM Triton X-100 was used as the draw solute. Moreover, a nanofiltration (NF) membrane was employed to recover the draw solute, achieving a high rejection of 95% due to the high charge and large size of the draw solute.