Use of Radioactive Tracers in the Development of New Chemical Processes

Radioactive tracers, principally 36Cl, 95S and 14C, have been used to help solve a large number of exploratory (laboratory) and process development (semi-technical) problems arising in an Industrial Research Laboratory. The uses of 14C discussed include the determination of the relative rate of formic acid oxidation (in carboxylic acid mixtures) to carbon dioxide and the determination of the origin of carbon dioxide and a number of oxidative by-products in a hydrocarbon oxidation system. As an example of the use of Geiger-Müller detectors and 36Cl tracer, an investigation into the fate of chlorine added to an oxidation system is described. Determination of the partition coefficient of sulpholane in hydrocatbon-water mixtures and the measurement of the amount of sulpholane adsorbed onto a solid catalyst during the reaction of a hydrocarbon (containing small amounts of sulpholane) are described as typical uses of 35S. Extensive use has been made of liquid scintillation counting and it has been found necessary to extend existing techniques and develop others, including the preparation and use of solid crystalline derivatives of aldehydes and organic acids, for the determination of specific activities of aldehydes and organic acids, for the dispersion of coloured solids by ultra-sonic energy before counting in a thixotropic gel and for the accurate determination of the specific activity of carbon dioxide absorbed in solvents such as Hyamine. The full experimental procedures used are described, and the scope and limitations of these developments discussed. (author)