ADSORPTION KINETICS OF Pb(II), Cd(II) AND Cr(III) ON ADSORBENT PRODUCED BY PROTECTED-CROSSLINKING OF HUMIC ACID-CHITOSAN - Umaningrum, Dewi; Department of Chemistry, Faculty of Mathematics and Natural Sciences, Lambung Mangkurat University, Jl. A. Yani Km 35,8 Banjarbaru, Kalimantan Selatan, 70714 (Universitas Gadjah Mada, 2010)