Nonaqueous Liquid/Liquid Interfaces: Surface Activity at the Interface betweenn-Paraffins andN-Alkyl Derivatives of 2-Pyrrolidone

✍ Scribed by Anjing Lou; Brian A. Pethica; P. Somasundaran

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 130 KB
• Volume: 202
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5454

✦ Synopsis

tures of acetonitrile and hexane with ethanol or methanol While nonaqueous liquids are widely used commercially, the using the drop-volume method. Ross and Kornbrekke (4) interfacial chemistry of nonaqueous liquid/liquid systems has remeasured contact angles at a glass wall near the critical ceived scant attention. In this paper interfacial properties of parpoint for several pairs of partially miscible organic liquids, tially miscible two-component systems of n-hexadecane with 2including the aniline-cyclohexane system. They reported pyrrolidone, N-methyl-2-pyrrolidone or N-ethyl-2-pyrrolidone, that, contrary to the prediction made by Cahn ( 5), the conand of n-heptane with N-methyl-2-pyrrolidone at 25ЊC are pretact angle goes to 90Њ at the critical point. This raises doubts sented. The surface activity of the long-chain N-alkyl-2-pyrroliabout the results (near the critical points) of Atack and Rice dones at these interfaces was also studied. The adsorption of the (1) and of Guha et al. (2), who assumed zero contact angle long-chain pyrrolidones increases with chain length following a modified form of Traube's rule. Partition coefficients for the long-to interpret their capillary-rise measurements. Durian et al. chain pyrrolidones at low concentrations were measured, and stan-(6) reported anomalous meniscus inversions near the critical dard free energies of transfer between the coexisting bulk phases solution points of two binary organic mixtures. and between each bulk phase and the interface were calculated.

The work reported here was not directed to interfacial At higher concentrations, the interfacial tensions of the longer behavior close to critical points, but interfacial tension meachain pyrrolidones go toward zero as the systems become more surements well away from the critical region can be influmiscible. The temperature variation of the hexadecane/N-methylenced by contact angle problems. For example, a contact 2-pyrrolidone and the hexadecane/ N-ethyl-2-pyrrolidone interfaangle has been observed on a platinum Wilhelmy plate at the cial tensions were also measured.