A Universal Procedure for Crude Glycerol Purification from Different Feedstocks in Biodiesel Production: Experimental and Simulation Study

It is important to utilize crude glycerol, the main byproduct of biodiesel production, to manufacture high value-added chemicals. Since crude glycerol typically contains less than 65 wt % glycerol, purification is the first step for its utilization. Owing to the wide variety of triglycerides, alcohols, catalysts, and separation processes used in biodiesel production, crude glycerol composition varies widely, leading to different crude glycerol purifications. In the present work, we develop a universal procedure for crude glycerol purification, including as key steps initial microfiltration of the crude glycerol, saponification, acidification, phase separation, and biphasic extraction of upper- and lower-layer products. The procedure was utilized to purify crude glycerol samples from two biodiesel production companies, experimentally upgrading both samples to >94 wt % purity. On an Aspen Plus software platform, the purification procedure was simulated using a process model based on two submodels to obtain a good match with the experiments. The developed procedure is suitable for the purification of crude glycerol obtained from different biodiesel production technologies.