Impact of process condition on glycerin recovery from spent lye

This study investigates the recovery of glycerin from spent soap lye derived from the saponification process using palm oil. At different batches, various quantities of brine solution of 8-15% w/w concentration heated at temperatures of 150 to 190 ℃ were used to investigate the effects of these on the process alongside a consideration of the effect of catalysis. The average yield obtained on variation of the brine dosage for the catalyzed and uncatalyzed processes were 60 and 56.88%, respectively; whereas temperature consideration gave average yield of 58.5 and 57.05%, respectively. Results showed that catalysis had a slight impact on the process in terms of yield. In all cases lower quantities of the brine solution gave higher yield of the glycerin whereas at higher temperatures, higher yields were obtained; with the best yield of 63.75% obtained at 190 ℃ with 50 g of 12% w/w brine solution. R2 values for the models predicting the effect of quantity and temperature on glycerin yield for the catalyzed and uncatalyzed processes were 0.983, 0.980 and 0.961, 0.957, respectively showing a high positive correlation between these variables.