SINTESIS Fe3O4/SiO2 TERMODIFIKASI (N-(2-AMINOETIL)-3- AMINOPROPIL) UNTUK ADSORPSI-DESORPSI ANIONIK [AuCl4]-; SYNTHESIS OF (N-(2-AMINOETHYL)-3-AMINOPROPYL) MODIFIED Fe3O4/SiO2 FOR ANIONIC [AuCl4]- ADSORPTION-DESORPTION

Mighfar Syukur, Naryono

2014 | Disertasi | PROGRAM STUDI S2 KIMIA

The synthesis of Fe3O4/SiO2 modified with N-(2-aminoethyl)-3- aminopropyl group (Fe3O4/SiO2/ED) and investigation Au(III) recovery in the multimetal system Au(III)/Cu(II)/Cr(VI) have been conducted. Fe3O4/SiO2/ED was synthesized via Stöber’s modifications method with methanol as dispersant of magnetite. Precursor sodium silicate and N-(2-aminoethyl)-3-aminopropyl trimethoxy silane (EDS) was added as aminosilica shell shaper. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer and transmission electron microscopy (TEM). Experimental parameter affecting Au(III) adsorption onto Fe3O4/SiO2/ED such as pH, contact time, initial concentration were studied. Study of kinetic data was analyzed using first-order, second-order, pseudo-first-order and pseudo-second order. Furthermore, the Langmuir and Freundlich isotherm models were used to determine it’s capacity and adsorption energy. Desorption by thiourea-HCl 2% and the reusability of adsorbents were done by adsorption-desorption cycle. The characterization with XRD, FT-IR and TEM proved that SiO2 and N- (2-aminoethyl)-3-aminopropyl group was successfully covered the magnetite particle to form Fe3O4/SiO2/ED adsorbent. Study of kinetic data showed that the adsorption of Au(III) on Fe3O4/SiO2/EDS fits to pseudo-second order model with rate constant of adsorption is 0.710 g mmol L-1min-1. The best interpretation for the experimental data was given by Langmuir isotherm model. The maximum adsorption capacity for Au(III) is 142.85 mg/g and the energy of adsorption is 25,052 kJ/mol. Gold loaded on the adsorbent could be easily desorbed by 0,2 mol/L HCl containing 2% of thiourea with 99,82% efficiency. The reusability Fe3O4/SiO2/ED shows the high stability of the adsorbent within 5 times adsorption-desorption cycle with more than 90% efficiency. Adsorbent also shows selectivity in adsorbing Au(III) in the multimetal system Au(III)/Cu(II)/Cr(VI) with the coefficient selectivity

Kata Kunci : Recovery, selectivity, Gold, Fe3O4, Silica modified