Synthesis of flocculant aids for cane sugar juice clarification: Part II – Dependence of clarification efficiency on intrinsic viscosity of cationic homopolymer

Investigation of a range of cationic homopolymers (poly(trimethyl-ammonium ethylmethacrylate chloride), poly(TMAEMAC)) as flocculant aids for cane sugar juice clarification showed a weak dependence of efficiency on solution intrinsic viscosity (IV), which is an indicator of molecular mass. As homopolymers giving lower IV were used, better turbidity reduction was obtained. The dependence is stronger when higher concentrations of polymer are used. How-ever, the polymers showing a high IV give poor performance at all concentrations. There is some evidence that the turbidity is correlated with the density of the final precipitate: flocculant aids producing a higher final precipitate level gave a higher turbidity than control runs, indicating they may be acting to some degree as dispersants. The effects seen have been interpreted in terms of the dominance of a charge-patch mechanism in the action of these homopolymers. With increasing polymer concentration, a reduced settling rate was seen for all flocculant aids, consistent with a charge-patch mechanism. The role of chain transfer agents is non-trivial and may be related to hydrolysis of the ester functionality of the polymer to give products with lower charge densities.