| The effects of small halocarbons, CHCl{dollar}sb3{dollar}, CHBr{dollar}sb3{dollar}, and CCl{dollar}sb4{dollar} at 50 mg/L on the performance of three typical RO membranes were examined. Cellulose acetate, polyamide, and advanced composite membranes were used. Five parameters were evaluated for each membrane/halocarbon combination. Flux, total dissolved solids rejection, halocarbon rejection, partition coefficient, and void volume tests were conducted in order to evaluate the effects of halocarbon addition. In general, the halocarbons were poorly rejected by all three membranes, increased rate of flux decline, and increased total dissolved solids rejection over controls without halocarbons. Partition tests revealed advanced composite membranes absorb all three halocarbons much more strongly than either cellulose acetate or polyamide membranes. The strong halocarbon adsorption for the composite was proposed as the main mechanism for membrane swelling which caused flux decrease and total dissolved solids rejection increase. The strong affinity for halocarbons suggests that the advanced composite membranes should not be used for treating waters containing halocarbons. |
