Glycerin Removal in Biodiesel Purification Process by Adsorbent from Rice Husk

Biodiesel is traditionally purified by water washing pocess. The possibility of reducing wastewater in biodiesel purification was investigated using adsorbents which was activated carbon and extracted silica from rice husk ash (RHA). Activated carbon was produced by treating rice husk ash with ZnCl2 in the weight ratios of 1:0.25, 1:1 or 1:2 (RHA : ZnCl2), followed by the carbonization at 700 °C. Extracted silica was produced by heating rice husk at 700 °C, followed by the treatment of 2.5 N NaOH. The biodiesel was directly purified by using 5% wt. of adsorbents, 150 rpm of agitation rate, at 50 °C for 10 min. The result showed that glycerin could be removed up to 84.8%. The regenerated silica could be used up to five times with 75-80%. The adsorption isotherm of this process was fit to Langmuir model