STARCH DERIVATIVES FOR FLOCCULATION OF FERRIC SOAPS

Although water soluble synthetic polymers find wide applications as flocculating agents, the potential problem associated with their use is lack of biodegradability and high cost. Development of substitutes based on natural polymers can be more attractive from biodegradability point of view and the important factor here will be matching the performance. We have studied the flocculating effects of starch derivatives (cationic and anionic) for ferric soap flocculation at different pHs and compared their efficiency with synthetic flocculants like Zeetag-63 and Floc-acid-25. Charge interaction between colloidal particles and polymeric flocculating agents is one of the factors that contribute to the changes in rate and extent of flocculation. Under certain pH conditions starch based flocculants are shown to perform better than the synthetic flocculants (Zeetag-63) and the effects are explained on the basis of variation of surface charge (measured by colloid titration) of ferric soaps precipitated at different pHs.