A new approach for salts removal from crude glycerin coming from industrial biodiesel production unit

The aim of the present work is to propose purification and cleaning of the residual salt from the crude glycerin purification step from distillation, using relatively simple physicochemical processes and easy industrial implementation. For this purpose, Total Organic Carbon (TOC), chloride content, metal analysis (Na, K, Ca and Mg), glycerol content, moisture content, total solids and ash content were employed to characterize the crude sample. The crude sample was extracted using different solvents (methanol, ethanol, chloroform, and dichloromethane), where methanol proved to be the most efficient solvent for extracting the organic phase of the sample under study. It was evaluated the ratio of residual salt:solvent (1:3, 1:5 and 1:10) which afforded the highest extraction efficiency as well as the required reaction time for the same (1, 5, 10 and 15 min). After obtaining the treated sample, it was subjected to the same characterization analyzes of the crude sample, for comparison. Results indicate that both the yield and quality of the recovered salt are governed not by the time of contact, but by the residual salt:solvent ratio. A significant reduction in total organic carbon (TOC) was observed between crude and treated samples, which was accompanied by an expressive increase in salt content, mainly for chloride and sodium ions. From a social and economic point of view, the purification of sodium chloride salts allows the use of a residue with potential application as a mineral salt.