Mass transport in the membrane air-stripping process using microporous polypropylene hollow fibers: effect of toluene in aqueous feed

Membrane air-stripping (MAS), using microporous polypropylene hollow fiber membrane modules, is one of the most promising processes for removal and recovery of volatile organic compounds (VOCs) from water/wastewater. In this work, aqueous feed containing VOCs was allowed to cross-flow on the shell side, whereas air flowed through the lumen of fibers. Chloroform, toluene and their mixture were used as model VOCs. The effects of presence of toluene alone and in mixture with chloroform in aqueous feed on the mass transport of VOCs through the membrane are reported. It was found that Henry’s law constants (HLCs) for toluene as well as chloroform did not change significantly in mixtures. The tests showed that higher toluene adsorption than that of chloroform on the fibers. It appeared that toluene blocked the pores partially, due to its strong affinity for the membrane material, resulting in substantially reduced mass transport.