we can conclude that the type of adsorbent employed only affects the combined alkalinity parameter, and the amount of adsorbent used affect only the turbidity. For all other parameters, the kind and amount of adsorbent employed did not affect the results. In general, we can conclude that all of the adsorbents employed in this study are effective in the removal of impurities of the biodiesel.
In summary, the use of natural and biodegradable adsorbents (cellulose and starch), is very interesting for application in the industrial process of biodiesel preparation, due to the effectiveness of the removal of contaminants and mainly due the fact that this purification step can be carried out at room temperature avoiding heating the biodiesel and preventing the generation of sub-products by the thermal degradation of biodiesel.