The purpose of this research is to improve the adsorption eff iciency of diatomite by heat treatment for purifying bidiesel. Al heat-treated diatomites were subjected to adsorb glycerine in biodiesel synthesized from palm oil via a base-catalyzed process. The optimal adsorption was obtained by varying ratio of adsorbent to biodiesel, contact time and temperature. By using 2% wt of diatomite and heat-treated diatomite at 800℃ at 50℃ for 30 minutes, the glycerne in biodiesel could be drastically removed. Furthermore, the removal of glycerine was improved by using 1% (w/w) of diatomite and heat-treated diatomite at 800℃ on the condition that methanol had been removed before treatment, According to the adsorption isotherm, this process is fit to Langmuir model.
