A model colloid for flocculant testing

This paper proposes dextran sulphate-modified precipitated calcium carbonate particles (DS-PCC) as a new colloidal model. Negatively charged dextran sulphate adsorbs on positively charged PCC surfaces, changing the surface charge from positive to negative, and sterically stabilizing the PCC particles. The characterization of this new model is given and its utility as a colloidal model in wet-end retention is demonstrated by its flocculation behaviour in the presence of cationic polyacrylamide, and poly(ethylene oxide) in conjunction with commercial cofactor, added as retention aids.