MODIFIKASI Mg/Al HIDROTALSIT DENGAN ASAM GALAT DAN APLIKASINYA UNTUK ADSORPSI-REDUKTIF AuCl4;? MODIFICATION OF Mg/Al HYDROTALCITE USING GALLIC ACID AND ITS APPLICATION FOR REDUCTIVE-ADSORPTION OF AuCl4?

Elianasari, Sri Juari Santosa

2015 | Disertasi | FMIPA

Modification of Mg/Al hydrotalcite using gallic acid for reductiveadsorption of AuCl4? has been investigated. Mg/Al hydrotalcite has been synthesized by coprecipitation method of Mg(NO3)2 and Al(NO3)3 at pH 10. Modification of Mg/Al HT was done by interaction of Mg/Al hydrotalcite with 100 mg/L gallic acid solution at pH 5 (Mg/Al HT-AG-1). The calcination effect of Mg/Al HT-AG-1 for adsorption gallic acid was done by two step. The first step Mg/Al HT-AG-1was calcined at 450 °C (Mg/Al HT-AG-1C) and reacted with gallic acid solution to form Mg/Al HT-AG-2. The second step, Mg/Al HT-AG-2 was calcined (Mg/Al HT-AG-2C) and reacted with gallic acid solution under same condition to form Mg/Al HT-AG-3. The models of kinetic and isotherm adsorption were also studied. The result of synthesized Mg/Al hydrotalcites were characterized by X-ray Diffraction and FT-IR Spectroscopy. The result showed that the defect structure of Mg/Al HT-AG-1 after the calcination and reconstructed to the original structure after interacted with 100 mg/L gallic acid solution. The concentrations of gallic acid on Mg/Al HT, Mg/Al HT-AG-1C and Mg/Al HT-AG-2C were 43.9824; 75.5672 and 59.4224 mg/g mg/g, respectively. The isoterm data were correlated with Langmuir isoterm model and the AuCl4? adsorption capacities of Mg/Al HT-AG-1, Mg/Al HT-AG- 2, and Mg/Al HT-AG-3 were 175.4385; 112.3595; and 86.2026 mg/g, respectively and the adsorption kinetics followed the pseudo-second-order Ho with rate constants were 9.8139 x 10-4; 3.2972 x 10-3 and 9.8006 x 10-4 g/mg.minute, respectively. The characterization using XRD showed that Au(III) could be reducted into Au(0) by Mg/Al HT-AG-1 and the characteristic peak of gold particle were at 2?; 37.40; 43.50;63.94 and 76.96°.

Kata Kunci : Mg/Al hydrotalcite; gallic acid; reductive-adsorption, AuCl4? ion.