Before washing rice hull with clean water, all impurities were separated and removed. 43 Next, rice hull was incubated at 100 oC for 24 hours and ground by ball-mill. Then, the 44 ground rice hull was boiled in 500 mL of 0.1 M hydrochloric acid (HCl) by using heating 45 mantle for 4 hours. After that, it was washed by deionized water followed by incubation at 46 100 oC for 24 hours. Next step, all rice hulls were incinerated at 600 oC for 4 hours. Finally, 47 the remaining silica from calcination was ground by ball-mill for size reduction.