Removal of residual catalyst from palm oil-based biodiesel using new ionic liquids analogous

Biodiesel is produced through transesterification of triglyceride and methanol in the presence of alkali catalyst to form glycerol and biodiesel. Purification methods are implemented to remove undesired products that are retained inside biodiesel. The purified biodiesel grade should adhere to international standard specifications EN 41214 and ASTM D6751. Residual potassium hydroxide (KOH) catalyst is one of the impurities in produced biodiesel which can be removed by deep eutectic solvents (DESs). DESs were formed by a salt and two hydrogen bond donors (HBDs). In this work, choline chloride (ChCl) was used as the salt while glycerol and ethylene glycol were used as the hydrogen bond donors. Six DESs were synthesized with various compositions of salt and HBDs to remove KOH catalyst. All DESs (DES1, DES2, DES3, DES4, DES6 and DES7) were successful to reduce KOH content in biodiesel. The results had demonstrated the removal efficiency of KOH increase with the increase of DES:biodiesel molar ratios and mole fraction of HBD in the mixture of DES. The optimum DES to biodiesel molar ratio for each DES was determined. The result had indicated DES4 as the best solvent for removal of KOH from biodiesel.