ISSN (Print): 2328-3777, ISSN (Online): 2328-3785, ISSN (CD-ROM): 2328-3793 American International Journal of Research in Formal, Applied & Natural Sciences AIJRFANS 14-246; © 2014, AIJRFANS All Rights Reserved Page 91 Available online at http://www.iasir.net AIJRFANS is a refereed, indexed, peer-reviewed, multidisciplinary and open access journal published by International Association of Scientific Innovation and Research (IASIR), USA (An Association Unifying the Sciences, Engineering, and Applied Research) Molar volume and rheology of anionic surfactants in non-aqueous media Suman Kumari a *, Mithlesh Shukla a , and R.K Shukla b a Department of Chemistry , Agra College, Agra-282004, India b Department of Chemistry ,R.B.S. College, Agra-282004, India I. Introduction Surfactants are surface active agents usually organic compounds, characterized by the possession of both polar and non-polar regions in the same molecule. This dual nature is responsible for the phenomenon of surface activity, micellization and solublization. The dual nature of a surfactant is typified by metal alkanoates, can be called association colloids, indicating their tendency to associate in solution, forming particles of colloidal dimensions. While major developments have taken place in the study of metal alkanoates of mono-carboxylic acid, the study of di-alkanoates of di-carboxylic acid is almost untouched. Burrows et al 1 synthesized di-carboxylic acid metal alkanoates by metathesis and Ikhuoria et al 2 studied the effect of temperature on the stability of metal alkanoates of dicaboxylic acids. Suzuki 3 prepared and investigated the thermal dehydration of manganese(II) dialkanoate anhydrides in various atmospheres. Liu et al 4 synthesized different metal dialkanoates such as calcium glutarate, zinc glutarate, calcium sebacate and zinc sebacate and discussed their use as thermal stabilizers for PVC material. Barbara and Lacz 5 studied the thermal decomposition of cadmium butanedioate dihydrate. A number of workers have reported ultrasonic 6,7,9 measurements of metal alkanoates for the determination of ion-solvent interaction in organic solvents. Viscometric 7-9 conductometric 9-10 measurements of lanthanide and transition metal alkanoates have been reported in different organic solvents. The focus of this paper is to look in to the bulk behavioral aspects like apparent molar volume and rheology(viscosity/ fluidity) of zinc mono-(hexanoate and decanoate) and di-(butanedioate and hexanoate) alkanoate by using density and viscosity measurements in a mixture of benzene and methanol (50% v/v) at 30±0.05⁰C. II. Experimental All the chemicals used were of BDH/AR grade. Solvents benzene and methanol were purified by distillation under reduced pressure. Zinc mono- (hexanoate and decanoate) alkanoates were synthesized by direct metathesis of corresponding potassium alkanoates as mentioned in our earlier publications 6,10 , while di- alkanoates of zinc were synthesized by metathesis in alcohol solution. The zinc di-alkanoates (butanedioate and hexanedioate) were first prepared by dissolving the dicarboxylic acid in hot ethanol, followed by treatment with potassium hydroxide solution. To this mixture, solution of the zinc salt was added slowly with continuous stirring. The precipitated alkanoates of the dicarboxylic acid was filtered off, washed with hot water and air- dried. The alkanoates were purified by recrystallization with alcohol and dried under reduced pressure. The purity was checked by their melting points (hexanoate-130.0 ⁰ C decanoate-92.0 ⁰ C and butanedioate-310.0 ⁰ C hexanedioate-263.0 ⁰ C) and absence of hydroxylic group was confirmed by IR spectra. The reproducibility of the results was checked by preparing two samples of the same alkanoates under similar conditions. The solutions of zinc mono- and di-alkanoates were prepared by dissolving a known amount of alkanoates in a benzene-methanol mixture (50% v/v) and were kept for 2 hr in a thermostat at 30±0.05ºC temperature. The zinc mono- and dialkanoates do not possess high solubility in pure solvents thus measurements were conducted in benzene - methanol mixture. Densities of the solvent and solution were measured by pyknometer. The Pyknometer was calibrated with distilled water and buoyancy corrections were applied. Ostwald type viscometer was used for measuring viscosity (±0.002) of the solutions. Abstract : The apparent molar volume, and fluidity for the solution of anionic surfactants ie. zinc hexanoate and decanoate as mono-alkanoates and butanedioate and hexanedioate as dialkanoates in a mixture of benzene-methanol (50% v/v) at 30ºC have been evaluated from the data of density and viscosity. The value of CMC decreases with increasing chain length of fatty acid constituent The limiting apparent molar volume, has been calculated by Masson’s equation. Keywords: Anionic surfactants, metal alkanoates, density, molar volume, fluidity, rheology.