COMPETITIVE ADSORPTION STUDY OF Ag(I) AND Cr(III) ON HUMIC ACID

Abstract

This research was carried out to investigate the ability of humic acid to adsorp Ag(I) and Cr(III) as a single and multiple metal ion. For this purpose, humic acid was isolated from peat soil that was taken from Pontianak, West Kalimantan. This study included: the isolation of humic acid; the influence of acidity, time, and concentration to metals adsorption; and the competition of metals in their optimum condition. Humic acid was extracted using base and was precipitated using acid. Then, the isolate of humic acid was characterized by means of infra red (FTIR) and UV-Vis. Characterization of humic acid by means of FTIR spectrofotometry showed the bands of OH, C-H aliphatic, C=O    carboxylic    acid,   and   C=C    aromatic.   Based   on   UV-Vis spectrophotometry, there was no any sharp peak. Only a slightly peak that seen at 260-280 nm. Base on influence of acidity to metals adsorption showed that Ag(I) was maximum adsorbed at pH 8 and Cr(III) at pH 3. Base on influence of time showed that Ag(I) reached the equilibrium at the 120^th minute and Cr(III) at the 80^th minute. Adsorption of ion Ag(I) reached equilibrium at 40 ppm and Cr(III) at 10 ppm. Adsorption of Ag(I) followed the first-order kinetic, meanwhile Cr(III) followed the second-order kinetic. Isotherm adsorption of Ag(I) and Cr(III) followed the equation of Langmuir. Metals competition of Ag(I) and Cr(III) showed competition of two metals, Ag(I) was maximum adsorbed however the acidity conditions