Reactive extraction of carboxylic acids using organic solvents and supercritical fluids: A review

Reactive Extraction of Lactic Acid using Environmentally Benign Green Solvents and Synergistic Mixture of Extractants

“…The production cost of LA is mainly dominated by its downstream processing cost, which involves 30 to 40% of the total LA production costs [6]. Therefore, the progress of competitive and economic techniques of product (LA) separation and puri cation from the aqueous waste streams and from the fermentation broth has become the recent focus of research from both the environmental and economic points of view [7,8]. The industrial and traditional technique of LA separation is precipitation, which uses calcium hydroxide and large amounts of sulfuric acid and further produces solid waste, i.e., calcium sulfate (environmentally unfriendly) as a by-product [8,9].…”

“…Therefore, the progress of competitive and economic techniques of product (LA) separation and puri cation from the aqueous waste streams and from the fermentation broth has become the recent focus of research from both the environmental and economic points of view [7,8]. The industrial and traditional technique of LA separation is precipitation, which uses calcium hydroxide and large amounts of sulfuric acid and further produces solid waste, i.e., calcium sulfate (environmentally unfriendly) as a by-product [8,9]. In order to reduce the cost, various extraction methods (such as adsorption [10], membrane separation [11,12], electrodialysis [13,14], ultra ltration [15], and extraction [16,17]) have e caciously been applied to the extraction of LA.…”

“…All these methods possess several speci c disadvantages (such as poor extraction e ciency (%), being uneconomical, the generation of huge amount of wastewater, high complexity, high energy consumption, and large production of by-products) [13]. Among all of the aforementioned techniques, reactive extraction has been considered as one of the best options for these conventional methods due to its various merits such as ensuring a high-purity product with minimum cost, being comparatively e cient and cheap while requiring a relatively short amount of processing time, being easy to scale up, being environmentally safe, high selectivity, and increasing the recovery by using a combination of extractants, organic solvents, and natural non-toxic solvents [8,18].…”

“…To date, on an industrial scale, most of the LA reactive extraction techniques use only Petroleumbased Organic Solvents (POSs) (such as alcohols, ethyl acetate, and aliphatic hydrocarbons), which are found to be unsuitable for LA recovery from the diluent aqueous streams (low in concentration) due to very high a nity of LA with water molecules (i.e., hard to isolate), giving a low distribution coe cient [7,8]. The high cost of these POSs, toxicity, poor process safety, non-renewability, non-biodegradability, environmental pollution problems during solvent regeneration, ammability, depletion of world petroleum reserves, undesirable in uence on the activities of biochemical substances (such as microbes), and the pertinent progress of environmentally benign technologies have been considered in the dynamic research on environmentally benign green solvents for the separation and puri cation of LA from the aqueous solution [7,19].…”

Organic phase screening for in‐stream reactive extraction of bio‐based 3‐hydroxypropionic acid: biocompatibility and extraction performances

“…[36][37][38] It has been suggested that the addition of a biocompatible but poor extractive solvent (inert solvent) to the active alcohol-type diluent can improve the biocompatibility of the extracting phase while maintaining an adequate extraction performance. [38][39][40][41][42] Solvents may affect cells at two different levels: by direct contact with the immiscible part of the solvent (phase-level toxicity) and interaction with the water-soluble solvent molecules (molecular-level toxicity). 40,43,44 The toxicity of several organic solvents commonly used for the reactive extraction of carboxylic acids has been assessed on different strains of microorganisms, 18,36,41,43,45 but the variable and often contradictory results suggest that the selection of a biocompatible extraction phase depends strongly on the microorganism strain used.…”