Comparison of Extraction Solvents on Separation Performance of Indole Contained in Crude Methylnaphthalene Oil

This study experimentally examined the separation performance of indole (IN) contained in crude methyl naphthalene oil (CMNO) by methanol extraction and then compared these results with formamide extraction. CMNO containing about 4.36% IN, which is attracting attention as an intermediate raw material such as medicine, essential amino acids, and perfumes, was used as a raw material, and methanol aqueous solution was used as a solvent, respectively. The increase in the initial volume fraction of water in the solvent (y(w,0)) sharply decreased the distribution coefficient (m(IN)) and yield (Y-IN) of IN, but conversely increased the selectivity of IN in reference to 2-methylnaphthalene (2MNA). An increase in the initial volume ratio of solvent to feed (E-0/R-0) increased m(IN), Y-IN, and beta(IN),(2MNA.) In the range of 0.1 <= y(w,0) <= 0.3, m(IN) and Y-IN of methanol extraction were approximately 1.9 similar to 5.9 times and 1.8 similar to 3.6 times greater than those of formamide extraction, respectively, whereas beta(IN,2MNA) of formamide extraction were 4.6 similar to 8.2 times greater than those of methanol extraction.