IMMOBILISASI ASAM GALAT PADA Mg/Al HIDROTALSIT DAN APLIKASINYA UNTUK REMOVAL AuCl4?; IMMOBILIZATION OF GALLIC ACID ON Mg/Al HYDROTALCITE AND ITS APPLICATION TO REMOVAL OF AuCl4 ?

DYAH FITRIANI, Sri Juari Santosa

2013 | Disertasi | PROGRAM STUDI S2 ILMU KIMIA

Immobilization of gallic acid on Mg/Al hydrotalcite has been conducted and applied to removal of AuCl4?. Mg/Al hydrotalcite (Mg/Al HT) has been synthesized by coprecipitation method of Mg(NO3)2 and Al(NO3)3 at pH 10 with Mg(II) and Al(III) molar ratio of 2 : 1. The synthesized Mg/Al HT as well as its immobilization product with gallic acid (Mg/Al HT-AG) before and after being used to remove AuCl4? were characterized by X-ray Diffraction and FT-IR Spectroscopy. The effect of pH on removal of AuCl4?, kinetic and isoterm adsorption, and effect of addition 2-propanol as OH radical scavenger were also studied. The gold metal formed was confirmed by difractogram XRD. Immobilization of gallic acid was reached at pH 5. The analytical result using FTIR and XRD showed that gallic acid has been immobilized on surface of Mg/Al HT with adsorption capacity which was determined according Langmuir isoterm model was 86.957 mg/g. Removal of AuCl4? by Mg/Al HT-AG was optimum at pH 3 and followed pseudo-second order kinetic model and Langmuir isotherm model with rate constant (k) and adsorption capacity were 7.70 x 10-4 g/mg minute and 125 mg/g respectively. Characterization with XRD showed that Au(III) could be reduced to Au(0) with peak of gold particles in difractogram were at 2 theta 38?, 44? and 64?. The addition of 2-propanol gave no significant effect on the reduction of AuCl4? to Au(0), showing that OH radical did not have dominant role on the reduction of AuCl4? to Au(0).

Kata Kunci : Mg/Al hidrotalsit; asam galat; AuCl4?; removal