Synthesis of a lignin-based alcohol ether carboxylate surfactant and its application as cotton fiber detergent

Alkyl glycidyl ether and 3-chloropropionic acid were grafted onto alkaline lignin (KL) to obtain lignin-based alcohol ether carboxylate surfactant (KLS) and its structure, surface tension, emulsifying ability and detergency of cotton fiber were investigated. Then, the alkaline lignin was pretreated by using ultrasound to activate the KL molecular. The pretreated KL showed lower Mn and narrow molecular weight distribution. The absorbance ratio of A1125/A1600 and A1047/A1600 of pretreated KL increased as the time of the ultrasound increased, indicating that new phenolic hydroxyl groups were formed. Further study revealed that the Mn, surface tension and emulsifying ability were significantly affected by the reaction temperature and ultrasound treatment. The sample (KLSU) obtained at 70 °C with ultrasound pretreatment had a good surface activity and emulsifying ability. The critical micelle concentration of KLSU was 3.1 g/L and the corresponding surface tension was 29.1 mN/m. The KLSU was used as a novel surfactant for detergent and exhibited significant detergency property. The effect of different types of surfactant on the detergency, zeta potential, surface tension and particle distribution of mixture solution containing KLSU were investigated. The KLSU solution mixed with sodium dodecyl benzene sulfonate showed good detergency, surface tension and stability. This article highlighted the potential usage of lignin-based alcohol ether carboxylate surfactant in detergent.

将烷基缩水甘油醚与3-氯丙酸接枝至碱性木质素（alkaline lignin, KL）上，制备得到木质素基醇醚羧酸盐表面活性剂（lignin-based alcohol ether carboxylate surfactant, KLS），并对其结构、表面张力、乳化能力及棉纤维去污性能进行了表征与研究。随后采用超声预处理对碱性木质素进行分子活化，经超声处理后的碱性木质素数均分子量（Mn）更低，且分子量分布更窄。随着超声处理时间延长，预处理后碱性木质素的A1125/A1600与A1047/A1600吸光度比值逐渐升高，表明体系中生成了新的酚羟基。进一步研究表明，反应温度与超声预处理工艺对产物的数均分子量（Mn）、表面张力及乳化能力具有显著影响。于70℃下经超声预处理制备得到的样品（KLSU）展现出优异的表面活性与乳化能力，其临界胶束浓度（critical micelle concentration, CMC）为3.1 g/L，对应的表面张力为29.1 mN/m。将KLSU作为新型洗涤剂用表面活性剂，其表现出优异的去污性能。研究了不同类型表面活性剂对KLSU复配溶液的去污力、Zeta电位、表面张力及粒径分布的影响，结果显示，KLSU与十二烷基苯磺酸钠（sodium dodecyl benzene sulfonate）复配得到的混合溶液具备良好的去污力、表面活性与稳定性。本研究证实了木质素基醇醚羧酸盐表面活性剂在洗涤剂领域的应用潜力。