Separation of soap, glycerol and water from biodiesel produced in a continuous biodiesel production process

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Biodiesel is produced from renewable lipid feedstocks, such as vegetable oil and animal fats. Generally, oil andmethanol are reacted in the presence of a catalyst to yield biodiesel and glycerol as a by-product. Biodieselobtained after separation from the by-product contains impurities such as soap, water, glycerol and freepotassium ions that affect the performance of biodiesel adversely. These impurities need to be separated frombiodiesel to meet the requirements of ASTM standards. The company, BIO-LIQ INC, tried to eliminateimpurities by using synthetic resins, but the resins imparted H+ ions (acidity) and water into the biodiesel in acontinuous process. Ion-exchange resins having negatively charged sulphonate group are able to removepositively charged impurities (H+, potassium and sodium ions, soap, free glycerol) from the crude biodieselwhile silica-based resin (SIPERNAT) with large surface area for adsorption is capable of trapping all types ofimpurities. In order to respond to the need of the company to purify biodiesel in a continuous process, anappropriate resin needs to be selected which can remove impurities so that the biodiesel follows the ASTMstandards. First, a batch study will be conducted to treat crude biodiesel with different resins. Then, the selectedresin will be tested in a continuous column operation where process parameters (flow-rate, columnback-pressure) and impurities in the purified biodiesel will be continuously monitored. The continuous processof biodiesel purification using column operation is economical, effective and industrially feasible unlikewet-washing techniques requiring a large amount of expensive solvents and produce large amount ofwastewater. The process developed from the proposed research will help BIOLIQ and other industries ofCanada to produce biodiesel in a continuous mode, eliminating the use of large holding tanks.