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以十四酸、十六酸、硬脂酸和二乙醇胺为原料,NaOH为催化剂,经酯化和水解二步法合成C14、C16、C18脂肪酸二乙醇酰胺类非离子表面活性剂,研究了各类脂肪酸二乙醇酰胺合成条件。测定了产物表面张力并确定了3种产物的临界胶团浓度(cmc),考察了无机盐对系列产物表面张力的影响,并测试了产物的起泡能力。结果表明,C14、C16、C18脂肪酸二乙醇酰胺形成临界胶团的浓度(cmc)分别为10、5、1mg/L,对应的表面张力分别为28.91、27.57、26.15mN/m。无机电解质浓度越高,产物水溶液的表面张力降低得越多,阳离子价态数的高低对产物表面张力影响不大。合成产物的起泡能力不强,但其消泡速率比较小,在0.37～0.6ml/min之间,说明合成产物的稳泡性能较好。
C14, C16, C18 fatty acid diethanolamide nonionic surfactants were synthesized by two steps of esterification and hydrolysis using myristic acid, palmitic acid, stearic acid and diethanolamine as raw materials and NaOH as catalyst. Fatty acid diethanolamide synthesis conditions. The surface tension of the product was measured and the critical micelle concentration (cmc) of the three products was determined. The effects of inorganic salts on the surface tension of the product were investigated, and the foaming ability of the product was tested. The results showed that the critical micelles concentration (cmc) of C14, C16 and C18 fatty acid diethanolamide were 10,5 and 1 mg / L, respectively. The corresponding surface tension were 28.91, 27.57 and 26.15 mN / m, respectively. The higher the concentration of inorganic electrolyte, the more the surface tension of the product aqueous solution decreases, and the cations of the valence state have little effect on the product surface tension. The foaming ability of the synthesized product is not strong, but its defoaming rate is relatively small, between 0.37 ~ 0.6ml / min, indicating the foam stability of the synthesized product is better.