KINETIKA ADSORPSI ION EMAS(III) OLEH HIBRIDA MERKAPTO SILIKA

Abstract

Abstrak: Telah dilakukan kajian kinetika adsorpsi ion emas(III) oleh adsorben hibrida merkapto silika (HMS). HMS disintesis melalui proses sol-gel dengan prekursor natrium silikat (Na₂SiO₃) dari abu sekam padi. HMS dibuat dengan menambahkan asam klorida pada campuran senyawa 3-(trimetoksilil)-1-propantiol (TMSP) dan larutan Na₂SiO₃. Kinetika adsorpsi ditentukan dengan melakukan adsorpsi sistem statik (batch) dengan variasi waktu. Jumlah ion emas yang teradsorpsi dihitung secara kuantitatif berdasarkan selisih konsentrasi logam sebelum dan setelah adsorpsi yang dianalisis dengan spektroskopi serapan atom (SSA). Data menunjukkan interaksi HMS dengan ion emas cenderung mengikuti pola kinetika reaksi pseudo orde-2 dengan nilai konstanta laju reaksi (k) = 1x10^-2 g mg^-1min^-1. Berdasarkan nilai perubahan energi bebas Gibbs adsorpsi standar (-ÃâGð= 34,63-37,99 kJ/mol) menunjukkan bahwa adsorpsi berlangsung secara kimia (kemisorpsi).

Kata kunci: kinetika, emas, merkapto, silika, abu sekam padi, pseudo orde-2.

Abstract: Adsorption kinetics study has been done of gold(III) ions by mercapto silica hybrid (MSH) adsorben. MSH was synthesized by sol-gel process with sodium silicate (Na₂SiO₃) from rice husk ash as a precursor. MSH made by adding hydrochloric acid to 3-(trimetoksilil)-1-propantiol (TMSP) compounds and Na₂SiO₃ solution. Adsorption kinetics are determined by adsorption static system (batch) with variation of time. The amount of the adsorbed gold ions is quantified by the difference in metal concentration before and after adsorption analyzed by atomic absorption spectroscopy (AAS). The data showed, MSH interaction with gold ion tends to follow the pattern of reaction kinetics pseudo-second-order with rate constant (k) =1x10^-2 g mg^-1min^-1. Based on the value of the standard Gibbs free energy for adsorption (-ÃâGð= 34,63-37,99 kJ/mol) showed that the adsorption takes place chemically (chemisorption).

Keywords: kinetics, gold, mercapto, silica, rice husk ash, pseudo-second-order.