羧甲基化木质素在阿维菌素颗粒表面的吸附行为

摘要

The analysis by FT-IR, GPC and functional groups content tests indicated that carboxymethylated lignin ( CML) had higher molecular weight, lower polydispersity, less phenolic hydroxyl and more carboxyl content than those of alkali lignin ( AL) . In order to investigate the feasibility of using CML to disperse avennectins particles in aqueous suspension, the adsorption isotherm, kinetics and thermodynamics of CML on avennectins particles surfaces were studied by batch equilibrium experiments. The results showed that the adsorption of CML was fitted to Langmuir isotherm equation, and the saturated adsorption amounts and Langmuir constants decreased with temperature increasing. The maximum saturated adsorption amount was 9. 569 mg/g, and 00. This indicated that the adsorption was a spontaneous, exothermic and entropy process. Theoretically, high temperature was not beneficial to the adsorption process. The values ofΔHad = -5. 18 kJ/mol implied that Van der Waals forces were responsible for the binding of CML with avennectins. The values of Ea =14. 23 kJ/mol indicated that the adsorption process was physical adsorption. The SEM showed that abamectin particle surface was smooth without hole structure. Abamectin particles adsorbed by CML could prevent particle from aggregation effectively, and increase physical stability of abamectin SC. The adsorption characteristics study demonstrated that CML was able to form stable adsorption on avermectin particles surfaces, and eligible to be used as a suspending agent in avermectin suspension.%通过凝胶渗透色谱、红外光谱和官能团含量测定表明经过羧甲基化改性后的碱木质素的分子质量增加,多分散性降低；分子中酚羟基含量减少,羧基含量增加。在此基础上采用振荡吸附实验研究了羧甲基化木质素( CML)在阿维菌素颗粒表面的吸附等温线、动力学和热力学。结果表明,吸附等温线符合Langmuir模型,饱和吸附量和吸附常数均随温度升高而降低,最大饱和吸附量为9.569 mg/g,00,表明该吸附为自发、放热、熵增过程；由ΔHad为-5.18 kJ/mol, Ea 为14.23 kJ/mol可知该吸附过程属于物理吸附,主要作用力为范德华力。 SEM分析表明,阿维菌素颗粒表面光滑无孔型结构,吸附CML后可有效阻止阿维菌素团聚,增加其悬浮剂物理稳定性。由此可知,CML能够在阿维菌素颗粒表面形成稳定吸附,适合作为分散剂用于阿维菌素水悬浮剂。