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 M_n 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 M_n, 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.