Mini Review of Biodiesel by Integrated Membrane Separation Technologies That Enhanced Esterification/Transesterification

Nowadays, the production of biodiesel from various renewable sources is becoming increasingly urgent because fossil fuels are becoming less and less available and accessible. Biodegradability, non-toxicity, and low pollution emissions are merely some properties making biodiesel a more environmentally friendly fuel. Esterification/transesterification is the most commonly used method to produce the biodiesel, whose reaction products are water/glycerol and mixed fatty acid esters. The membrane separation methods are applied to remove water/glycerol, which is capable of upsetting the chemical equilibrium of esterification/transesterification controlled by thermodynamics and facilitating the reaction to proceed forward accordingly. The integrated membrane separation process is coupled with the chemical reaction, which could isolate a certain product from the reaction system with the reaction going on. That means that it is possible for the membrane separation technology to burst the restraints of original chemical equilibrium to gain the higher equilibrium conversion rate and yield. In comparison to other methods, the membrane separation technique coupled with chemical reaction has the ability to increase the reaction conversion rate, shorten the reaction time, and evenly reduce energy consumption.