Hydrophilic polymers as stabilisers and flocculants of sulphadimidine suspensions

Abstract

The effect of various grades of polyvinylpyrrolidone (PVP), sodium carboxymethylcellulose (SCMC) and acid and alkaline gelatins on the flocculation behaviour of sulphadimidine suspensions has been studied. These polymers induce both flocculation and stabilization of the suspension depending upon the polymer concentration used. Each polymer exhibited an optimum concentration for flocculation. Higher concentrations of the polymer induced some degree of steric stabilization.

The principles of controlled flocculation were tested by determining the relationship between the electrophoretic mobility and the sedimentation volume of the suspended particles. Although these principles were applicable to the SCMC/sulphadimidine suspensions in that the sediment volume increased as the stability decreased, PVP/sulphadimidine suspensions behaved differently in that the sediment volume decreased with decrease in mobility and this was attributed to steric stabilization by the polymer. It was therefore concluded that by the use of these polymers one can produce the desired degree of flocculation in suspensions by selection of the type, fraction and concentration of polymer.