Relationship of structure to properties of some anionic surfactants as collectors in the flotation process. 1. Effect of chain length

The surface and thermodynamic properties of some synthetic surfactants, as well as their efficiency as collectors in the flotation of petroleum coke, are studied. These surfactants are monoisomeric alkylbenzenesulfonate of di fferent alkyl chains (C12 to C14). The results show that the length of the hydrocarbon chain of these surfactants plays a major role in determining th eir surface and thermodynamic properties. The values of surface excess conc entration (Gamma(max)) and Gibbs energy of micellization (Delta G(mic)(o)) are found to increase with increasing number of carbon atoms in the chain w hile the values of critical micelle concentration (cmc) are decreased. The results indicate, also, that there is a good relationship between effective ness of adsorption of a surfactant and its efficiency as a collector. A sur factant of higher Gamma(max) produces a concentrate of lower ash content an d higher flotation yield. Thus, the surfactant with longer alkyl chain (C14 ) and highest Gamma(max) value is more selective, as a collector, than othe rs of shorter carbon chain.