| A new type of cationic Gemini surfactants with amide group were synthesized using N,N-dimethyl-1,3-propanediamine, palmitic acid, epichlorohydrin and aliphatic amines, and their surface chemical properties and application were studied.First, hexadecyl amide propyl dimethyl amine was synthesized using palmitic acid and N,N-dimethyl-1,3-propanediamine. Reaction time was 12h, which was determined by acid value. The yield was 91%. Then bis(2-hydroxy-3-chloropropyl) alkylamines were synthesized using epichlorohydrin and aliphatic amines (1-dodecylamine, 1-Tetradecanamine, 1-hexa decanamine). The yield was 83%, 86.6% and 84%, respectively. Finally, Gemini Cationic Surfactants were prepared by reaction of hexadecyl amide propyl dimethyl amine and bis (2-hydroxy-3-chloropropyl) alkylamines. The factors that affect yield of the targets were studied, and the better process conditions listed below: the temperature is 86°C, molar ratio is 1:3, reaction time is 24 hours, and the amount of catalyst is 1%.The contact angle of cationic Gemini surfactant on the surface of glass was studied; The surface tension of the products was determined at 45°C, the results showed that the surface tension increased from 43.73mN/m to 46.49mN/m, and the critical micelle concentration values decreased from 1.4×10-4mol/L to 8.24×10-5mol/L as the length of carbon chain increased. Compared with the critical micelle concentration (cmc) of CTAB, the cmc of Gemini surfactants was below 1-2 orders of magnitude. The ability to reduce the surface tension decreased, while the efficiency of reducing the surface tension enhenced with the increase of carbon chain length. The counter-ion binding degree of Gemini surfactants decreased when the temperature increased. Micellization free energy results showed that the association process of the surfactant micelles was a spontaneous process, with the reduction of standard free energy. Dynamic light scattering experiments showed that the average hydrodynamic radius of the surfactants increased from 30.0nm to 51.2nm as the length of carbon chain increased, and the Gemini surfactant formed as Non-spherical aggregates in the concentration of 1×10-3mol/L. Rheological experiment showed that the viscosity of products decreased as shear rate increased, the viscosity of Gemini cationic surfactants c1 increased with the increase of concentration, and it had a rapid increase when the concentration up to 6g/L. The solubilization of Gemini cationic surfactants to toluene was 6-8 times higher than that of CTAB and the Gemini cationic surfactants also showed better emulsion capacity to liquid paraffin than CTAB.We preliminary studied on the Gemini cationic surfactants used to modify montmorillonite (MMT). The Gemini cationic surfactants were used as organic intercalation agents to modified Na-montmorillonite. FTIR and TGA indicated that Gemini cationic surfactants were intercalated into the galleries of MMT. The d-spacing of modification with the surfactants was increased from 1.47 nm to 3.42 nm,3.68 nm and 3.48 nm, and the Gemini surfactants can be more effective at expanding the d-spacing than traditional quaternary ammonium cationic surfactant CTAB. After modification, the surface energy of the montmorillonite decreased, the surface polarity reduced. The adsorption amount of modified montmorillonite to chlorine was 6 times higher than that of Na-montmorillonite, which provided a promising application on the removal of the organic pollutes in wastewater. |
PDF Full Text Request