Question

Hey guys. Could you please help me? I've done the transesterfication step for biodiesel production. However, due to limited amount of lipid available, the reaction was carried out using only 62mg of lipid and excess methanol and catalyst was used. Please read below:

Answer 1

12ml of methanol and 0.125g of catalyst (Sodium hydroxide) was used. For the removal of impurity to get the pure biodiesel, we had to evaporate the methanol at 80 degrees and pass the biodiesel through magnesol. However, while evaporating the excess of methanol, the sample has dried out and some brownish precipitate was observed, among some green pigments, on the wall of the container and when methanol was added, a yellowish solution was obtained. Could you suggest what happened while evaporating the methanol? What could have happened to the biodiesel? Thank you for your help.