Microwave assisted extraction is more efficient in terms of yield and time consumption as it can achieve a maximum
extraction within 4 minutes, which cannot be achieved through conventional soxhlet method even after 6 hours. The
limestone based catalyst derived from cement clinker showed an efficient conversion (up to 96.9%) of high FFA rubber
seed oil to biodiesel. The results suggest that the catalyst employed in this work is not negatively affected by moisture and
free fatty acids and can be recycled very easily without a significant loss in its activity. The biodiesel produced in this work
is within the limits of specification described by ASTM D6751