Abstract:
This work is carried out to purify and convert crude glycerol derived from waste used-oil methyl ester plant to valuable chemical compounds. The first part was the purification of pre-treated crude glycerol by chemical process. The effect of varying the types of polar extract (methanol, ethanol and propanol) and non-polar extract (hexane and diethyl ether) and volume ratio of extract to pre-treated crude glycerol on the purity of purified crude glycerol was investigated. The results demonstrated that the propanol at the volume ratio to pre-treated crude glycerol of 2.0 provided the highest purity of purified crude glycerol of 97.85% with the color reduction of 94.96%. The second part was the synthesis of valuable chemical compounds from purified crude glycerol by electrochemical technique in un-divided electrochemical reactor. Effects of initial pH (1, 7 and 11), current density (0.08-0.27 A/cm²), electrode types and hydrogen feed rate were explored. The results indicated that the use of Pt as electrode, initial pH of 1 and the current density 0.14 A/cm² provided the highest glycerol conversion (97.00 %) within 17 h electrolysis time. The presence of hydrogen gas in the system can enhance a fast conversion and production yield of valuable compounds compared with that in the absence of hydrogen gas. Valuable compounds generated by the electrochemical conversion of purified crude glycerol were glycidol, 1,2-propanediol, 1,3-propanediol and etc.