ing with the surfactant (adsorbate). Moreover, interactions The influence of variables such as adsorption temperature, polar between surfactant and solvent should also be allowed for. chain length, and nature of functional groups on the adsorption, There are some internal factors such as the length and nature from aqueous solutions, of various surfactants (TX-114, TX-100, of the polar chain of the surfactant and nature of the solid TX-165, TX-305, NP1P4E, NP4P1E, NP4S, NP10S, and NP25S) surface that must be taken into account. Somasundaran et has been investigated. Several nonporous solids, including various al. (5) related the length of the ethoxyl chain with the conforsamples of quartz, QA (5.1 m 2 g 01 ), QB (5.5 m 2 g 01 ), and QC (4.0 mational behavior of the adsorbed molecules. Sobisch (6) m 2 g 01 ) , kaolin (19.3 m 2 g 01 ), and dolomite (0.3 m 2 g 01 ), were observed that the adsorbed amount increases with a decrease studied. Conformational changes of adsorbed surfactant molecules on QC quartz, when the oxyethylenic length of Tritons increases, in the of degree of ethoxylation. Bo ¨hmer et al. (7), using have been detected. For all the other solid samples the surface is an extension of the self-consistent-field theory of Scheutjens not completely covered by Tritons. On quartz, the surfactants are and Fleer for chain molecules (8), calculated the adsorption adsorbed by hydrogen bonds between the surfactant's ether groups isotherms of polyoxyethylenic surfactants. They found, in and the silanol groups of the solid surface. These hydroxyl groups agreement with experimental findings, that the critical mimust be free and sufficiently separated from other hydroxyls of the celle concentration (cmc) increases and the aggregation solid surface. When the number of propoxy groups increases (from number of micelles decreases as the hydrophilic block be-NP1P4E to NP4P1E) the adsorbed amount of surfactant on the comes longer. Some external factors which affect the adsorpsolid studied decreases. Anionic surfactants are adsorbed on quartz tion behavior (9-15) are adsorption temperature, salinity, in lower amounts than the corresponding nonionic surfactants. However, the adsorbed amounts of Tritons and sulfated Tritons on pH, etc. Thus, Gaufres et al. (16) found conformational kaolin are similar, probably due to the positive charges on the edges changes as a function of temperature in an E n E m (oxyethylof this material.