Reactivating Adsorption Capacities of Spent Bleaching Earth for Using in Crude Palm Oil Industry

The spent bleaching earth from the palm oil refining industries contains various contaminants, including free fatty acids and hazardous material. The conventional procedure is harmful to the environment. In this study, spent bleaching earth (SBE) was successfully regenerated by calcination and acid-activation process. The calcination process was performed at 500, 600 and 700°C for 2, 3 and 4 h. All samples were then mixed with CaCO₃ and lastly activated with aqueous acid. The results showed the SBE color restored at calcination temperature higher than 500°C, even though the decomposition of the volatile compound was removed at 680°C according to thermal gravimetric analysis. Treatment affected the clay structure and mostly removed the impregnated organic matter. The primary phase of regenerated SBE is similar to virgin bleaching earth (VBE), implying the calcination and acid-activation is not alter the phase. Moreover, the adsorbent capacity of regenerated SBE was comparable with VBE, showing the regenerated SBE has promising potential for many applications, in particular for the palm oil refining industry. Regenerated SBE gave significantly larger specific surface area, microporous surface area and total pore volume with smaller the average pore diameter.