IMOBILISASI ASAM HUMAT PADA KITOSAN DENGAN METODE PENGIKATAN-SILANG TERPROTEKSI UNTUK ADSORPSI Pb(II), Cd(II), DAN Cr(III); IMMOBILIZATION OF HUMIC ACID ON CHITOSAN BY PROTECTED-CROSSLINKING METHOD FOR ADSORPTION OF Pb(II), Cd(II), AND Cr(III)

Uripto Trisno Santoso, Sri Juari Santosa

2012 | Tesis | PROGRAM STUDI S3 KIMIA

Immobilization of humic acid (HA) through crosslinking on chitosan is interesting to be studied because HA possesses high ability to bind heavy metal ions but its solubility in aqueous medium at pH ? 5 is ? 95%. Prior to immobilization, protection of active site is necessary to be carried out since the carboxyl groups of HA as the active site in complexing metal ions can react with amine groups of chitosan. There were three crosslinking strategies that have been explored, the strategies were: (1) crosslinking using glutaraldehyde as a crosslinking agent that possesses two functional groups with same reactivity, (2) crosslinking using epichlorohydrin as a crosslinking agent that has two functional groups with different reactivity, and (3) crosslinking using 6-O-tosyl-N-phthaloylchitosan having one active functional groups. Protection was carried out by reacting HA with Pb(II), Cd(II), or reacting amine group of chitosan with phthaloyl group. Deprotection of Pb(II) and Cd(II) was performed by reacting adsorbent with Na2EDTA solution. The obtained adsorbents were tested for HA stability toward dissolution, characterized qualitatively using FTIR spectroscopy, XRD, and SEM, as well as determined their adsorption capacity toward Pb(II), Cd(II), and Cr(III). The results showed that each strategy could be applied to produce an adsorbent with different characteristics. Method I produced adsorbent with high adsorption capacity but low in stability. Method II and III produced adsorbent with high adsorption capacity and stability but the amount of immobilized HA is smaller than method I. Generally, the result showed that active site protection treatment produced adsorbent that possess adsorption capacity higher than that without active site protection treatment.

Kata Kunci : METODE PENGIKATAN-SILANG TERPROTEKSI; ADSORPSI