REMOVING SOME HAZARDOUS HEAVY METAL ANIONS BY USING A NEW ANION EXCHANGER

Cross-linked sawdust bearing tertiary amine functional groups having an average capacity of 88 mEq/100 g and a strength pK b of 10 have been found to be very efficient in removing some hazardous heavy metal anions (i.e., dichromate and permanganate) from their aqueous salt solutions. It was found that for a given set of treatment conditions, the lower the pH, the smaller the exchanger particle size range, the higher the agitation speed, and the lower the material-to-liquor ratio, the greater is the rate and extent of removal of dichromate anions from the surrounding medium. On the other hand, the effective exchange capacity as well as the affinity for hazardous anions are affected by contact time, pollutant concentration as well as type of heavy metal anion, and the percent removal followed the descending order: MnO 4 − > Cr 2 O 7 2− .