Study On The Synthesis Of Salt-tolerant Surfactants Started From Biomass

Using biomass cashew phenol, ethylene oxide, chloroacetic acid and sodium hydroxide as raw materials, a series of cashew phenol polyoxyethylene ether carboxylates (abbreviated as CPEC) anion-nonionic surfactants were prepared through the ring-opening polymerization reaction, alkaline reaction, carboxymethylated reaction, and acid-base neutralization reaction. Their structures were characterized by means of infrared spectroscopy and elemental analysis. Their water-solubility, surface/interface tension, wetting properties, foam properties and salt resistance were also studied.The Krafft point of product CPEC was determined to measure the strength of its water-solubility. The results showed that hydrophilicity enhanced, Krafft point decreased and water-solubility increased with the increasing of EO content. Using the Spinning Drop Tensiometer, the surface tension of pure aqueous solution and NaCl aqueous solution of product CPEC at 25℃were measured by spin-drop method. Through the curve of surface tension with concentration, the critical micelle concentration (cmc) and surface tension (γ_cmc) at the cmc of CPEC-8, 10, 12, 14 were obtained, and they were 9.30, 8.50, 8.10, 7.71mmol/L and 28.38, 28.60, 30.40, 30.00mN/m respectively. The results showed that foaming and foam stabilizing enhanced with the increasing of the concentration of CPEC, decreased with the increasing of temperature, decreased a little with the increasing of the concentration of Ca2+, Mg²⁺ and firstly increased and then decreased with the increasing of the concentration of NaCl. After reaching a certain degree, they kept the value all long. Foam performance of CPEC aqueous solution was determined by the Ross-Miles method. Wetting properties of CPEC aqueous solution on a hydrophilic glass slide were determined. Salt-tolerant capabilities of CPEC were determined and increased with the increasing of EO content and temperature. The interface tension of CPEC aqueous solution with n-alkanes was measured, in the right salt concentration, alcohol concentration, and the matching n-alkanes can form a lower interface tension. The interface tension of CPEC-14 aqueous solution was 0.0888mN/m when the concentration of NaCl was 6g/L and the volume concentration of n-pentanol was 1.5%.