Detail data of reactive extraction of caproic acid using tri-Butyl phosphate and Sunflower and Soybean oils as diluents

Caproic acid can be produced by fermentation technology. Reactive extraction method is a promising technology for separating the acid from the carboxylic mixture in the fermenter [1], [2], [3], [4]. To achieve it, tri‑butyl phosphate (TBP) is used as the reactive extractant and sunflower and soybean oils are used as the diluents. The performance of both the physical and reactive extraction processes was analysed by different parameters like distribution coefficient, loading ratio, and extraction efficiency. To meet the purpose, concentration of caproic acid in aqueous phase was measured by doing acid-base titration by caustic solution Further, reaction equilibrium constant, stoichiometry and distribution of complex, free acid and dimer concentrations in the organic phase were analysed. The data are related to the published (https://doi.org/10.1016/j.cep.2020.107926) paper in Chemical Engineering and Processing: Process Intensification [5]. The data shown in the current article are not provided in the mentioned published paper. Moreover, data are useful for understanding the physical and chemical behavior of the caproic acid extraction process and also can be used to design the process in industrial scale.


a b s t r a c t
Caproic acid can be produced by fermentation technology. Reactive extraction method is a promising technology for separating the acid from the carboxylic mixture in the fermenter [1][2][3][4] . To achieve it, tri-butyl phosphate (TBP) is used as the reactive extractant and sunflower and soybean oils are used as the diluents. The performance of both the physical and reactive extraction processes was analysed by different parameters like distribution coefficient, loading ratio, and extraction efficiency. To meet the purpose, concentration of caproic acid in aqueous phase was measured by doing acid-base titration by caustic solution Further, reaction equilibrium constant, stoichiometry and distribution of complex, free acid and dimer concentrations in the organic phase were analysed. The data are related to the published ( https: //doi.org/10.1016/j.cep.2020.107926 ) paper in Chemical Engineering and Processing: Process Intensification [5] . The data shown in the current article are not provided in the mentioned published paper. Moreover, data are useful for understanding the physical and chemical behavior of the caproic acid extraction process and also can be used to design the process in industrial scale. ©

Value of the data
• The experimental data can be used to examine the suitability of the extractant and green diluent for recovering caproic acid from fermentation unit. The data also help to identify the mechanism of mass transport of the caproic acid from aqueous phase to the organic phase. • The raw data provides distribution coefficient, chemical reaction equilibrium constant, reaction stoichiometry and distribution of caproic acid in different forms in the organic phase. These data can be used to develop phase diagram of the caproic acid reactive extraction system. The graph can be used further for finding number equilibrium stages. • These data alogn with mass balance equations can be used for designing continuous cocurrent and counter-current reactive extraction cascades.

Data description
The presented data in this paper corresponds to the measured concentrations of caproic acid at equilibrium state. The initial acid concentration in the aqueous phase were also presented. The concentration data were presented at five different temperature levels. The raw data are available in "RW" folder. Data using Sunflower oil and soybean oil as diluents are available in "SUN" and "SOY" folder, respectively. In "SUN" folder, physical and chemical extraction data are available in"phy-sun.xlsx" and "chem-sun.xlsx" files, respectively. Similarly, in "SOY" folder, "chem-soy.xlsx" and "phy-soy.xlsx" files, respectively contain chemical and physical extraction raw data. Data at different temperatures in the .xlsx files are available in different worksheets  Table 1 Structure of raw data (in .xlsx file) in physical extraction process. acid concentrations are tabulated in Tables 1 -8. TBP concentrations and temperaturers are used as the parameter. All the tables are available in "Chemtab.docx"file. The variation of partition coefficient (P) and dimerization constant (D) in case of physical extraction are depicted in Fig. 1 . Fig. 2 shows the graphical variation of K chem D .Thevariation of ln K E with 1/ T is shown in Fig. 3 . Fig. 4 shows the variation of ln K D with 1/ T .

Experimental design
The equilibrium reactive extraction of caproic acid from its aqueous solution was carried out by mixing the solution with organic solvent (TBP as extractant and sunflower oil or soybean oil as diluent) at a particular temperature. Complete experiment was performed for 12 h in incubator shaker to achieve the equilibrium state. Temperature was varied in the range of 298 to 318 K with 5 K increment.

Materials
Tri-n-Butyl Phosphate ( Loba Chemie Pvt. Ltd, India), with assay of 99%, was used as the reactive extractant. Caproic acid (Otto Chem. Ltd., India), with assay of 99%,was used. Sunflower oil (Agro Tech Foods Ltd, India) and soybean oil(Cargill India Pvt. Ltd.) were used as diluent.  NaOH (Fisher Scientific Chemicals Pvt. Ltd., India) was used for estimating caproic acid in aqueous phase using titration method. For standardizing NaOH solution, oxalic acid (Fisher Scientific, India) with assay 99%was used. Phenolphthalein (Merck Specialties Pvt. Ltd., India) was used as an indicator.

Methods
10 cc each of organic and aqueous phases were taken in a 100 ml conical flask and mixed for 12 h in an orbital incubator shaker. Temperature of the shaker was maintained from 298 K to 318 K. After 12 h, the mixture was allowed to settle in a separator for two hours maintaining the same experimental temperature. Further, the aqueous was titrated against caustic solution to know the equilibrium concentration of caproic acid in the aqueous phase. The concentration of caustic solution was measured by primary standard oxalic acid. The total concentration of

Table 2
Structure of raw data (in .xlsx file) in chemical extraction process.  caproic acid in the organic phase was estimated by mass balance. The distributions of K overall D , K chem D , [ HA m S n ] org , z and E% were estimated from the measured caproic acid concentration distributions using the different relations given in the submitted paper with manuscript number CEP_2019_1502 in Chemical Engineering and Processing: Process Intensification. Tables 2 and 3 .