Experimental investigation of forward osmosis process for boron removal from water

•Three FO membranes were applied for boron removal from water.•Boron solute flux increases with increasing draw solution concentration and boron concentration.•Increasing the feed solution and draw solution concentration enhanced the boron rejection rate.•Increasing boron concentration didn’t appear to have an effect on the boron rejection. Forward osmosis technology is one of the most rapidly developing processes of desalination and water treatment. The transport of boron in forward osmosis (FO) using various FO membranes was investigated in this study. Three specific membranes — an FTS H2O™ membrane, a PSU membrane and an Aquaporin Inside™ membrane — were applied to study the impact of the feed solution (FS) pH, boron concentration, and draw solution (DS) concentration on boron solute flux, boron rejection and water flux. The results indicated an increment in boron solute flux with increasing DS and boron concentration but a reduction with increasing FS pH. Moreover, increasing the FS pH from 4 to 10 enhanced the rejection rate of boron from 12% to 90% for the FTS H2O™ membrane, from 8% to 84% for the PSU membrane and from 8% to 76% for the Aquaporin Inside™ membrane. With increment in the DS concentration from 0.5 to 3 M, the rejection rate of boron increased from 20% to 54% for the FTS H2O™ membrane, from 14% to 50% for the PSU membrane and from 8% to 40% for the Aquaporin Inside™ membrane. Apparently, increasing the boron concentration in the FS did not have a significant effect on boron rejection. The boron rejection rate was approximately 20–30% for the Aquaporin Inside™ membrane, 32–40% for the FTS H2O™ membrane and 25–35% for the PSU membrane.