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.