To eliminate this problem, the use of waterless process
becomes an important role in removing biodiesel contaminants
then conventional water washing could be replaced by using
adsorbents. The study of various type of adsorbents is needed.
Bentonite clay was chosen to be adsorbent in this work because
of its ability to improve surface area and active site. Especially,
bentonite is a natural clay and it is available in Thailand with its
competitive cost.