Reactive Extraction as an Intensifying Approach for the Recovery of Organic Acids from Aqueous Solution: A Comprehensive Review on Experimental and Theoretical Studies

Organic acids are important targeted chemicals worldwide due to their variety of functionalities in various fields. Organic acids can be produced through chemical processes of fossil raw materials as well as by the microbial fermentation of natural occurring biomass. Because of growing environmental concern, the production pathways are shifting toward biobased green technologies. The primary challenge in the biological synthesis of organic acids is the downstream recovery of the main products from the fermentation broth/aqueous stream. Among the various techniques for the downstream processing, reactive (liquid) extraction is deemed as a great opportunity for this purpose. It is an energy-saving process with flexibility in production scale and a high degree of separation and selectivity. In this review, starting with highlighting the bioproduction and various alternatives available for the recovery of organic acids from aqueous solution, the reactive extraction, an intensified approach is described in detail. The influence of reactive extraction parameters, insights of equilibrium and kinetic mechanisms, and thermodynamic aspects are discussed and analyzed. Different theoretical models for process optimization, determination of equilibrium, kinetic, and thermodynamic parameters, and quantification of solvents' effect are also explained in detail. This paper also highlights recent experimental and theoretical studies for the recovery of different organic acids using amine, phosphorus, and ionic liquid based extractants from fermentation broth/industrial waste streams. In addition, industrial development on the recovery of organic acids using the reactive extraction approach is also described.

Automated summary

Organic acids play important roles in various fields and are increasingly produced using biobased green technologies. The main challenge lies in the recovery of products from fermentation broth/aqueous stream, with reactive extraction being identified as a promising solution due to its energy-saving nature and high separation and selectivity capabilities. Recent studies have focused on using reactive extraction for the recovery of different organic acids, highlighting its potential for industrial development.