A model colloid for flocculant testing

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