Recovery of l-tryptophan from dilute aqueous feed by extractive solvent sublation and solvent extraction methods and optimization

Abstract

The present investigation aims to recover l-tryptophan from a dilute aqueous solution. L-tryptophan, an essential amino acid, is indicated as an adjunct to antidepressant drug treatment. The recovery method is based on extraction such as conventional Solvent Extraction and Extractive Solvent Sublation. The technique is executed considering several factors: amounts of extractant, surfactant, initial pH, and flow rate of nitrogen gas (GFR). The procedure is optimized by response surface methodology using Statease Design Expert statistical software. Design models were generated to assess two responses% Recovery (RP) and Enrichment (ER) of amino acid. The validated models could explain well the effects of factors, the impact of the interaction between factors, and the quadratic effects. In the ‘solvent extraction’ method, various controlling parameters were varied by trial. Maximum percentage of extraction of amino acid of 70.29 and partition coefficient of 7.276 was observed at mole ratio (1:1) of amino acid and sodium lauryl sulfate, mole ratio (1:1500) of amino acid and extractant, Di-(2-Ethylhexyl) phosphoric acid, the aqueous- organic volume ratio of 3:1. In the ‘solvent sublation method, maximum% RP and ER were observed as ∼ 74.77% and 3.552. A high desirability value of 0.968 indicates the suitability of the models. The method is eco-friendly, simple, less costly, and does not require electricity. The extractive solvent sublation is preferred over conventional solvent extraction as the former can be operated with a lesser quantity of solvent.