Reactive Extraction of Alcohols from Apolar Hydrocarbons with Aqueous Solutions

Abstract

Use of aqueous solutions as reactive extraction solvents for the recovery of monohydroxyl alcohols present in few-percent concentrations in apolar hydrocarbons is evaluated. Two approaches are considered. The first, in which an aqueous solution containing a reactive extractant is applied for the recovery of the alcohol, shows only limited potential to be used. Among several potential extractants, only hydroxypropyl cyclodextrins and silver nitrate were able to achieve a slight improvement of the distribution ratio of benzyl alcohol relative to pure water. In addition to providing moderate values of the distribution ratios of benzyl alcohol, these extractants are also found to increase the solubility of the apolar organic solvent in the aqueous phase and thereby cause a decrease in selectivity toward the alcohol. The second considered approach, in which the alcohol is chemically modified prior to the extraction into an easily extractable form, in this case a monoester, has much more potential. A benign solvent, such as an aqueous solution of sodium hydrogen carbonate, can provide a distribution ratio of benzyl alcohol of up to 200, leaving the solubility of the organic solvent in the aqueous solutions unchanged relative to that in pure water. The modification of aromatic, cycloaliphatic, and linear aliphatic alcohols can be done efficiently in an apolar organic solvent without need for a catalyst. It is found that the back-recovery of alcohol extracted in this way can be performed by back-extraction after the monoester has been hydrolyzed. The rate of hydrolysis can be controlled by temperature. Hence, an efficient and selective recovery of alcohols can be achieved by reactive extraction using aqueous solutions of a hydrogen carbonate salt by modifying the alcohol into a monoester prior to the extraction.

Selective recovery of pyruvic acid from two and three acid aqueous solutions by reactive extraction

“…The theory of reactive extraction of carboxylic acids has been explained in detail previously and the method has been shown to be a promising purification technique for the recovery of metals, alcohols, carboxylic acids, amino acids, proteins and plant-derived products due to its efficiency and simplicity of approach. Moreover, since it is applied at low temperatures, it can be used for the purification of heat-sensitive substances [34][35][36][37][38][39][40][41][42][43][44][45].…”

Reactive extraction of carboxylic acids from apolar hydrocarbons using aqueous solutions of sodium hydrogen carbonate with back-recovery using carbon dioxide under pressure

“…The jacketed glass cells and applied procedure for the measurement of the distribution ratio of the components between the aqueous and organic phase are already described in our earlier papers [11,18,19]. Hence, only the specific details for this case are given here.…”