Hydrotropic properties of some short-chain alkylbenzene- and alkylnaphthalene sulfonates

Alkylbenzene sulfonates based on toluene, xylene and cumene, and alkylnapht halene sulfonates act as hydrotropes in surfactant systems. One measure of hydrotropicity is the amount of hydrotrope required to clear a cloudy deter gent formulation; some hydrotropes are more effective than others, dependin g on the surfactant formulation. Another measure is the modification of the viscosity of surfactant formulations; the change in the viscosity depends on the amount and type of hydrotrope used and on the specific formulation i nvolved. Additionally, alkylnaphthalene sulfonate hydrotropes change the so lubility of nonionic surfactants in water, and both types of hydrotrope rai se the cloud point of nonionic surfactant solutions; however, the naphthale ne-based hydrotropes are more efficient. Ross-Miles foam test data are used to compare the foam characteristics of different alkylnaphthalene sulfonat es. A critical micelle concentration (CMC) was determined for the alkylnaph thalene sulfonates, but although alkylbenzene sulfonates do show some surfa ce activity, a CMC could not be found for these materials.