Biodegradable starch was filled with wollastonite or bentonite (10 or 20% by mass) and used for prodn. of thermoplastic starch pellets by extrusion. The pellets were used sep. for the removal of Cd2+, Pb2+ and Cu2+ ions from 10 mmol solns. for 24 h. Pellets filled with 20% bentonite showed the highest sorption ability when compared with starch pellets (increase in sorption by over 300% for Pb, by over 400% for Cd and by almost 500% for Cu).