ADSORPTION KINETICSOF Pb(II), Cd(lI) AND Cr(lII) ON ADSORBENT PRODUCEDBY PROTECTED-CROSSLINKINGOF HUMICACID-CHITOSAN Kinetika Adsorpsi Pb(II),Cd(lI)dan Cr(lII)pada Adsorben Produk Pengikatan-Silang Terproteksi Asam Humat

ABSTRACT Study on adsorption kinetics of of Pb(II), Cd(lI) and Cr(lI1)on adsorbent which was produced by protectedcrosslinking of humic acid-chitosan has been done. The Langmuir-Hinshelwood,pseudo first- and second-order kinetics models were used to describe the kinetic data, and the rate const~nts of adsorption were also evaluated. The experimental data fitted well the second-order kinetics model, indicating that the chemical sorption is the ratelimiting step, instead of mass transfer. The initial metal ion concentration significantly affects the adsorption rate. An increase in initial meta! ion concentrationresults in the decrease in adsorption rate of the metals. Keywords: kinetics, adsorption, crosslinking, humic acid, chitosa