Ca(II) Extraction by D2EHPA from Calcium Lactate Solution to Produce Lactic Acid: Process and Kinetics

A new solvent extraction method that removing the Ca(II) from calcium lactate by Di-(2-ethylhexyl) phosphoric acid (D2EHPA) to produce lactic acid was proposed. The influences of composition of organic phase, phase ratio, temperature and calcium concentration, on extraction yield, were investigated. The optimal technological conditions of extraction were obtained: reaction temperature 323 K, phase ratio (O/W) 4:1, the initial calcium concentration 1.03 mol L–1, the D2EHPA volume fraction 40%, and 5% 1-octanol as modifiers. The reaction occurs at the interfacial zone possibly, and the rate is mostly controlled by chemical reaction. Reaction order with respect to H2A2, pH and Ca2+ was determined and the rate of calcium extraction could be expressed as: F = 10-6.81[Ca2+][H2A2]0.5[H+]-1.