SEPARATION OF BENZENE CYCLOHEXANE MIXTURES BY DIMETHYLAMINOETHYL METHACRYLATE GEL MEMBRANES FORMED IN PORES OF A THIN SILICA MEMBRANE

Dimethylaminoethyl methacrylate gels were synthesized by crosslinking with ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate (DEGDMA), or triethylene glycol dimethacrylate (TEGDMA). They swell in aromatic solvents but hardly at all in paraffinic solvents. The gels were formed in the pores of thin silica membranes. The composite membranes were used for separation of benzene/cyclohexane mixtures by the pervaporation method. As expected from the swelling-shrinking behavior of the gels in benzene/cyclohexane mixtures, benzene permeated selectively through the membranes. The selectivity depended on the length of the crosslinking agents used for synthesizing the gels, and increased in this order: EGDMA > TEGDMA> DEGDMA. Furthermore, the swelling-shrinking behavior in benzene/cyclohexane mixtures depended on temperature, because of the heat-sensitive property of gels, and even in cyclohexane, the swelling of gels was clearly noticed with increasing temperature. Thus the selectivity of composite membranes lowered with increasing the separation temperature.