Zone Refining of Anthracene

Abstract

A condition which minimize the time required to get the maximum fractional yield of purified material is investigated. General procedure derived is applied to find the condition of refining anthracene containing tetracene as an impurity. The optimum rate of zone travelling falls about 13 cm/h, and is little dependent on the desired degree of impurity separation. On the other hand, the optimum zone length in practical case is governed by the ingot length and the minimum interval between the adjacent zones. The maximum fractional yield under the optimum travel rate always amounts to about 65%. The content of tetracene in anthracene is estimated by a luminescence method down to the mass concentration of 10^-6. The functional relation between the travel rate and the distribution coefficient satisfies a general formula proposed by Burton; best fit is obtained with δ/D=360 s/cm. The magnitude of the equilibrium distribution coefficient of tetracene in anthracene is found to be 0.04.