Synthesis And Application Of Mono Alkyl Diphenyl Oxide Disulfonate

In this paper,Disodium monoalkyl diphenyl oxide disulfonates（MADS）with different carbon chains（C_n-MADS,n=8,12,16）were synthesized through the steps of alkylation-sulfonation-neutralization using fatty alcohols(C₈,C₁₂,C₁₆),diphenyl oxide and fuming sulfuric acid（20%free SO₃）as reagents.The structures of the products were identified by HLPC,Infrared Spectroscopy and Electrospray Ionization-mass Spectrometry.The surface activities,emulsification,wettability alteration and salinity and hardness tolerance of C_n-MADS were systematically investigated.Effect of inorganic salts（NaCl,CaCl₂ and Al₂（SO₄）₃）on the interfacial tension between C₁₆-MADS aqueous solution and paraffin liquid was investigated,and the washing oil efficiency of C₁₆-MADS aqueous solution with the presence of inorganic salts（NaCl and CaCl₂）were studied.The effect of alkylation conditions（temperature,material molar ration,catalyst added）and carbon chain length of alcohol on the alkylation reaction rate were studied.The cmc of C₈-MADS,C₁₂-MADS,C₁₆-MADS are 7.24×10^-3,1.49×10^-3 and 2.09×10^-4mol/L;and the surface tension at cmc(γ_cmc)are 37.5,38.9 and 46.8 mN/m;the emulsification of C₁₂-MADS is better than C₈-MADS and C₁₆-MADS,while C₈-MADS and C₁₆-MADS have no difference in the emulsifying ability;C₁₆-MADS can transfer the hydrophobic surface to a weak hydrophilic surface,while C₈-MADS and C₁₂-MADS can transfer the hydrophobic surface to a medium hydrophilic surface;MADS has more excellent salinity and hardness tolerance compares to conventional surfactants such as LAS.Addition of NaCl,CaCl₂ and Al₂（SO₄）₃ can decrease the interfacial tension between C_n-MADS aqueous solution and parrfin liquid,and the interfacial tension keeps in the range of 10^-1 mN/m;the interfacial tension between C₁₆-MADS aqueous solution and paraffin liquid can keep stable under a high concentration inorganic salts,which shows that C₁₆-MADS has the excellent salinity and hardness tolerance;the washing oil efficiency of C₁₆-MADS aqueous solution（0.3%wt）is about 10%higher than deionized water,NaCl and CaCl₂ have certain enhancement effect on washing oil efficiency of C₁₆-MADS aqueous solution.