Ethanesulfonic acid-based esterification of industrial acidic crude palm oil for biodiesel production

► Acidic crude palm oil is proposed as a raw material for biodiesel production. ► Ethanesulfonic acid is introduced as a new esterification catalyst. ► The acid was recycled for three batches with insignificant lose in efficiency. ► The produced biodiesel meets the international standards for biodiesel fuel.