Studi Kinetika dan Kesetimbangan Adsorpsi Ag(I) pada Kitin Terimobilisasi sam Humat = Kinetics and Equilibrium Studies of Adsorpsi Ag(I) by Humic Acid Immobilized on Chitin

Immobilization of humic acid on chitin has been conducted and applied for the adsorption of Ag(I). The humic acid was isolated from peat soil of Rawa Pening, Ambarawa, Central Java by using NaOH 0.1M, while chitin was isolated by deproteination of marine crab shells by using NaOH 3.5% and followed by demineralisation using HC1 1M. Parameter investigated in this study consisted of (1) method of immobilisation, (2) stability of immobilized humic acid, (3) effect of acidity on adsorption, (4) rate, capacity, energy and mechanism of adsorption. The results of characterisation showed that total acidity of the humic acid was 642.5 cmol/ kg, and it was distributed into the acidity of -COOH 342.5 cmol/kg and phenolic -OH 300 cmol/ kg. Chitin which was obtained from marine crab shell possessed degree of acetylation as high as 45.86%, contained N 4.63%, and ash contained 47.69%. Immobilization of humic acid on chitin has been successfully done by reacting chitin solution in HC1 0.01 M and humic acid solution in NaOH 0.01 M. The obtained adsorbent i.e. HAC contained humic acid 1.9 %, and the humic acid immobilized on HAC was stable up to pH 11. Adsorption of Ag(I) was maximum at pH 5-6, with rate of adsorption constants of 27 x 10-4, 22 x 10-4, 86 x 10-4 minute-1. for HA, HAC, and C, respectively. The capacity of adsorption was in the order of HA>HAC>C, i.e. 8.6 x 10-5, 5.3 x 10-5, 8.6x 10-5 mol/ g, respectively. The energy of adsorption of Ag(I) on HA, HAC, and C was 25.22, 26.29, and 28.93 kJ/mol, respectively. Keywords : immobilization, humic acid, chitin, adsorption, Ag(I