ADSORPSI SELEKTIF Au(III) PADA HIBRIDA AMONIUM KUATERNER-SILIKA DALAM SISTEM Au/Cu

Adsorption of Au(III) has been studied for an Au/Cu binary system on quaternary ammonium-silica hybrid material (HAKS) in a batch system. HAKS has been synthesized by reacting amino-silica hybrid (HAS) with methyl iodide in media of sodium bicarbonate solution and acetonitrile through reflux at 65oC for 24 hours. HAS was synthesized by using sodium silicate precursor that was extracted from rice husk ash and 3-(aminopropyl) trimethoxysilane through solgel method. The existence of material functional groups were identified by FTIR spectrophotometry, crystallinity by XRD, as well as surface area, diameter and pore volume were analyzed by BET and BJH methods. Adsorbed metal ions were analyzed by AAS spectrophotometer and materials which have interacted with the Au(III) were characterized by XRD. Adsorption of Au(III) was carried out as function of pH, contact time, and adsorbate concentration. Adsorption kinetics was determined by pseudo second order, Langmuir-Hinshelwood and Santosa model, while the adsorption isotherm is analyzed by the Langmuir and Freundlich models. FTIR and XRD characterization showed that the HAS and HAKS successfully synthesized. Conversion of the amino to a quaternary ammonium group increases the pore diameter from 72,428 to 91,478 Ǻ. Selective adsorption of Au(III) in binary Au/Cu system on HAS and HAKS is effective at pH 3. Adsorption kinetics studies showed that the adsorption of Au(III) on HAS and HAKS fits to pseudo second order model with adsorption rate constant of 31,89 and 2,08 mg g-1 min-1. Both materials show a linear plot of Langmuir isotherm models with adsorption capacity on HAKS lower (7,09 mg/g) than on HAS (63,25mg/g). HAKS also showed no higher selectivity coefficient for Au(III) toward Cu(II) than the HAS