Selective coprecipitation of colloidal manganese(IV) oxide

A cobalt-pyrrolidinecarbodithioate carrier complex coprecipitates manganese at the μg l−1 level, when present as Mn(II) in true solution and as colloidal MnO2 under one set of reaction conditions, but only as the colloid under another set. Filtration of the colloid through polycarbonate membranes of graded pore sizes provides conflicting pointers to the particle size distribution.