微波消解预处理碱木质素制备阳离子型表面活性剂

Preparation of Cationic Surfactant Derived from Alkali Lignin by Microwave Digestion Pretreatment

中文关键词:  碱木质素  表面活性剂  季铵化  微波消解

Key Words:alkali lignin  surfactant  quaternization  microwave digestion

中文摘要:

      以碱木质素（AL）为原料，采用微波消解预处理AL，随后采用季胺化反应制备得到木质素基离子型表面活性剂。探究H₂O₂用量、微波功率、微波时间对产物性能的影响，并利用电位滴定、傅里叶变换红外光谱仪、紫外-可见分光光度计和光学接触角测量仪等对AL及其季铵化产物（ALG）、微波消解预处理木质素（ALM）及其季铵化产物（即木质素基阳离子型表面活性剂，ALMG）进行表征。结果表明，微波消解预处理的最佳反应条件是：H₂O₂用量8.4 wt%、微波时间7 min、微波功率140 W。经微波消解预处理后，ALM的酚羟基含量明显提高（由AL的1.29 mmol/g提高至ALM的2.39 mmol/g）。经季铵化接枝后，ALMG具有较低的表面张力，相同质量浓度（0.1 g/L）下，ALMG溶液的表面张力为36 mN/m，显著低于ALG溶液的表面张力（47 mN/m）；ALMG临界胶束浓度值为0.6 g/L，可用作润湿剂。

Abstract:

      Lignin-based cationic surfactant derived from alkali lignin （AL） was prepared by microwave digestion pretreatment， accompanied by quaternization in this study. Effects of H₂O₂ dosage， microwave power， and microwave duration on performance of the obtained product were studied. Potentiometric titration， FT-IR， UV-vis， optical contact angle measuring were used to characterize AL and its quaternization product （ALG）， microwave pretreated lignin （ALM） and its quaternization product （i.e.‍， lignin-based cationic surfactant， ALMG）. The results show that the optimal conditions of microwave digestion are H₂O₂ dosage of 8.4 wt%， microwave duration 7 min， and microwave power 140 W. It is found that the hydroxyl content of ALM increased significantly from 1.29 mmol/g（AL） to 2.39 mmol/g after microwave digestion. The surface tension of quaternized ALMG solution （36 mN/m） was lower than that of its ALG counterpart （47 mN/m） at the same mass concentration of 0.1 g/L. Moreover， the critical micelle concentration of ALMG is 0.6 g/L， rendering it a promising candidate of wetting agent.