Using eco-friendly alternatives for the recovery of pyruvic acid by reactive extraction

Abstract

Efficiency, cost and environmental impact are important parameters that must be addressed in the recovery and purification of pyruvic acid (PA) from fermentation media. In this study, twelve vegetable oils were evaluated with three extraction agents for the reactive extraction of PA. Recoveries with trioctylamine (TOA) were significantly higher than those with tributylphosphate (TBP) and trioctylmethylammonium chloride (TOMAC). The reactive extraction yields with vegetable oils were similar and comparable to that with 1-octanol; among the tested oils, the highest efficiencies were achieved with almond oil. Efficiencies increased with higher extractant amounts, but were negatively affected by higher pH and PA concentrations. Higher temperatures caused slight negative effects on yields. Loading ratios (z) showed that 1:1 PA:Ext complexes most probably occur with all extractants tested; moreover, 2:1 PA:TOA may form due to the z values > 1 with TOA. The PA was stripped and organic phase was regenerated after two consecutive back extraction steps using 2.5 M NaNO3. Organic phases could be re-used 5 times with only a 1–2% decline in efficiency. Based on the performance parameters evaluated and extraction yields obtained, vegetable oils have the potential for use as organic phase diluents during reactive extraction of PA.