Sorption-desorption profile of Au(III) onto silica modified quaternary amines (SMQA) in gold mining effluent

Abstract

This work aim to study sorption-desorption of Au(III) onto silica modified quaternary amines (SMQA) in gold mining effluent. Synthesis SMQA was conducted by methylation silica modified ammine (SMA) that synthesized by sol-gel process of silica gel (SG) from rice hull ash and APTMS. Characterizations this material by FT-IR, XRD, SEM-EDS and GSA analyzer show that the material has characteristic parameter of SMQA. Sorption study of sorption Au(III) on SMQA was carried out by batch system with optimum pH 5. Sorption capacity was 74.47 mg/g (Langmuir) with 24 kJ/mole sorption energy (electrostatic interaction). Kinetics sorption studies by Lagergren, Ho, and RBS models shows that the sorption Au(III) in this research have the suitable condition with RBS models. Sorption study reveal that –N+(CH3)3 is the most responsible site for Au(III) sorption. Desorbed Au(III) in batch system using Na2S2O3, SC(NH2)2, and KSCN as desorption agent in HCl solution was there are no significant different value (Na2S2O3 = 94.2 %; SC(NH2)2 = 95.2 %; KSCN = 95.2 %). However, for safer eluent it was recommend to use Na2S2O3 or SC(NH2)2. The reusability of SMQA was four times sorption-desorption cycle before at fifth cycle desorbed Au(III) was decreased. The application of SMQA in gold mining effluent by column system (SPE) sample in Sarolangun, Jambi, Indonesia shows that recovered Au(III) was 0.000593 % in 2 g sample.