Adsorpsi Timbal dengan Hibrida Merkapto-Silika dari Abu Jerami Padi

Abstract

Silica gel is an adsorbent mostly used to adsorb heavy metals. Raw material for preparing silica gel is silicate (SiO2). Rice straw ash contains 94.5% Si, so that it is potential to be synthesized to silica gel. The weakness of silica gel as adsorbent is its low effectiveness toward metals adsorption, therefore active groups are needed to enhance its effectiveness. Silica gel mercapto-silica hybrid was made by adding HCl 3M to the mixture of 3-(trimethoxylil)-1-propanethiol (TMSP) and Na2SiO3 solution obtained from rice straw ash fused using NaOH until pH 7. The results were characterized using fourier transform infrared spectroscopy (FTIR), X-ray diffraction, energy dispersive x-ray (EDX), and scanning electron microscope. FTIR analysis showed that there were functional group of –CH2 on the silica gel TMSP but the expected –SH group was not detected. However, EDX result showed there was a composition of sulfur compound on silica gel TMSP. The modified silica gel with TMSP enhanced the capacity of Pb(II) adsorption. Commercial silica gel, the synthesized silica gel, and silica gel TMSP were all following Langmuir isotherm.