Optimization of organofunction PDMS membranes for the pervaporative recovery of phenolic compounds from aqueous streams

Exptl. studies for optimizing organofunctionalized PDMS membranes for the pervaporative recovery of phenolic compds. from water are presented. Four functional groups (acetate, Et ether, dimethylamino and pyridyl) were added to pure PDMS membranes with functional loading 10-25%. Composite membranes were fabricated and tested in short term trials with 5% (wt./wt.) phenol/water and 2% (wt./wt.) p-cresol/water binary systems. The influences of the pH and temp. of the feed soln. also were examd. Significant performance enhancements were achieved for functionalized PDMS membranes, esp. those loaded with either the dimethylamino or the Et ether group. The optimal loading level for the dimethylamino group is .apprx.20%. For this membrane, increasing the pH of the feed soln. within the range 5-8.5 doubled the selectivity for p-cresol/water sepn. For the phenol/water sepn., the effect is more modest. Increasing the feed temp. from 50 Deg to 90 Deg results in an increase of 300% in flux, but has a negligible effect on selectivity. [on SciFinder (R)]