BackgroundGlycerin is produced as an 11% by-product in biodiesel manufacturing. Impurities are concentrated in the glycerin phase. High-vacuum distillation of glycerin is an energy-intensive process. A new low-cost purification strategy for glycerin is needed. This paper reports the refining of the glycerin phase obtained from palm-oil biodiesel synthesis by ion-exchange with cationic resins. In the literature and to the best of the authors' knowledge, the use of a real glycerin phase from biodiesel has not been reported. The ion-exchange equilibrium was determined in a batch process, while variables for the industrial scaling-up were studied in continuous operation. ResultsThe sodium content obtained with low amounts of resin is lower than that obtained with mineral-acid refining. Almost complete sodium removal could be achieved in continuous operation. Langmuir and Freundlich models give a good fit to the equilibrium data. Amberlyst was the best resin. Breakthrough capacity was 96% of static exchange capacity. 95% of the static ion exchange was recovered by washing with water-soap. ConclusionA 96.6% purification level of glycerol was obtained with the resin Amberlyst 15, using a methanol content of 60%, liquid phase flow of 0.8 mL min(-1) and 0.3 g resin g(-1) glycerin phase; dynamic exchange capacity was 96% of the static exchange capacity. Exchange capacity is almost completely regenerated by washing with water-soap. (c) 2013 Society of Chemical Industry