Rice husk ash was collected from a local
rice mill factory. It was dried at 150o
C for 24 hours
to remove water content. The obtained RHA was
used in the experiment without any pre-treatment.
Sodium hydroxide (99%), sulfuric acid (98%), HCl
(38%), Na2CO3 and NH3 solution were acquired
from Ajax fine chem. All chemicals were reagent
grade or analytical grade and used as received.
The microwave oven was Electrolux EMM 2005,
which can adjust its power within the range of 300-
800 W. The conventional heater was from Grant
instrument (W28) with a power of 1500 W.