The Final Treatment: Washing or polishing followed by distillation offers the purest biodiesel around

Biodiesel Magazine
By Raj Mosali
May 01, 2012

Biodiesel is traditionally produced via esterification of fatty acids and transesterification of triglycerides with an alcohol such as methanol and sodium methylate. The transesterification of triglycerides is comprised of three sequential, reversible reactions wherein triglycerides react to form diglycerides, monoglycerides and glycerol.

All biodiesel processes, whether traditional or nontraditional, involve a settling process as the penultimate step. During the settling process, the biodiesel and glycerin mixture is settled using a decanter or a centrifuge to separate the biodiesel from the glycerin. The separated biodiesel is then taken through the final steps, which, in some cases, involve two stages: washing/polishing and distillation. Washing/polishing is mandatory and biodiesel distillation is optional. This article discusses both the washing/polishing and distillation stages.

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