Regeneration of Lactic and Succinic Acid-Laden Basic Sorbents by Leaching with a Volatile Base in an Organic Solvent

Leaching with an organic solution of a volatile base was explored as a method of regenerating tertiary amine and pyridyl sorbents. Experimental data are presented that show that regeneration efficiency correlates with the nonaqueous basicity of the regenerant as measured by the Gutmann donicity scale. Essentially complete regeneration of lactic acid-laden Dowex MWA-1 was achieved when 8−10 mol of trimethylamine were present for every mole of adsorbed acid; adequate (>70%) regeneration was obtained at a 2:1 molar ratio. The resulting trimethylamine−lactic acid complex can be thermally decomposed fully when trimethylamine is employed in an organic solvent instead of in water. A likely cause of the incomplete thermal decomposition of trimethylammonium lactate in previous, water-based systems is the aqueous environment in which the decomposition was performed.