摘要
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,0<RL<1表明该吸附易于进行;吸附动力学符合准二级动力学方程,吸附速率常数随温度升高而增加,吸附平衡时间约为60 min;吸附热力学结果表明:ΔGad<0、ΔHad<0、ΔSad>0,表明该吸附为自发、放热、熵增过程;由ΔHad为-5.18 k J/mol,Ea为14.23 k J/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。
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,and0 RL 1 indicated that the adsorption process was feasibility. The adsorption process followed the pseudo-second-order kinetic model with the entire adsorption,and the adsorption rate constants increased with temperature increasing. The equilibrium adsorption time was approximately 60 min. The thermodynamic parameters were obtained as ΔGad 0,ΔHad 0 and ΔSad 0.This indicated that the adsorption was a spontaneous,exothermic and entropy process. Theoretically,high temperature was notbeneficial to the adsorption process. The values of ΔHad=- 5. 18 k J / mol implied that Van der Waals forces were responsible for the binding of CML with avennectins. The values of Ea= 14. 23 k J / 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.
出处
《林产化学与工业》
EI
CAS
CSCD
北大核心
2015年第5期45-52,共8页
Chemistry and Industry of Forest Products
基金
“十二五”国家科技支撑计划资助项目(2011BAE06A06-10)
关键词
阿维菌素
羧甲基化木质素
吸附
动力学
热力学
avennectins
carboxymethylated lignin
adsorption
kinetic
thermodynamics
