Influence of carboxymethylated lignin as pesticide dispersant on adsorptionand dispersion

doi:10.11949/j.issn.0438-1157.20160592

Abstract

Abstract:

The study aimed to reveal the reason why carboxymethylated lignin (CML) had better dispersion properties than sulfomethylated lignin (SAL). It was found that hydrophilic property of CML was weaker than that of SAL by measuring the amount of hydrophilic group of CML and SAL, relative molecular weight and pure water contact angle on lignin coating. The measured adsorption isotherms of two lignin dispersants on carbendazim particles showed that the adsorption capacity of CML was higher than that of SAL, indicating that CML was easier to be absorbed on carbendazim particles than SAL. It was also found that the adsorption ability of CML was larger than that of SAL under the application of the Langmuir and Freundlich adsorption isotherm equations. It indicated that the adsorption affinity between weak hydrophilic CML and pesticides was stronger, and the adsorption between lignin and pesticides may be based hydrophobic adsorption. Further more, through simulate calculating the π-π force between lignin dispersants and carbendazim, it was found that the CML was easier to form a stable π-π effect with pesticides and to promote the adsorption. Due to the stronger adsorption affinity between CML and pesticides, the absorption capacity of weaker hydrophilic CML was higher, and thus CML can improve the Zeta potential of carbendazim particles, showing better dispersion properties.

Key words: lignin, hydrophilicity, carboxyl methylation, sulfonation, adsorption, pesticide

摘要：

为了揭示羧甲基化碱木质素CML较磺化碱木质素（SAL）对农药具有更好分散性能的原因，测定了CML和SAL的亲水基含量、相对分子质量及纯水在木质素涂层的接触角，发现CML的亲水性弱于SAL。对比了两种木质素分散剂在多菌灵颗粒上的吸附等温线，发现CML的吸附量比SAL大，并采用Langmuir、Freundlich方程进行拟合，可知CML的吸附能力大于SAL，说明木质素与农药之间的吸附可能以疏水吸附为主。进一步采用Gaussian模拟计算木质素分散剂与多菌灵的π-π吸附作用力，结果表明羧甲基化碱木质素更易与农药形成稳定π-π作用，进一步促进吸附。亲水性较弱的CML由于与农药具有更强的吸附亲和力，因而吸附量大，对农药颗粒Zeta电位的提高更大，从而具有更好的分散性能。

关键词: 木质素, 亲水性, 羧甲基化, 磺化, 吸附, 农药

CLC Number:

TQ450.4

PANG Yuxia, LI Yuan, ZHOU Mingsong, TAO Jiayuan, GAO Fei. Influence of carboxymethylated lignin as pesticide dispersant on adsorptionand dispersion[J]. CIESC Journal, 2016, 67(11): 4858-4865.

庞煜霞, 李媛, 周明松, 陶家媛, 高菲. 羧甲基化碱木质素对农药的吸附分散作用机理[J]. 化工学报, 2016, 67(11): 4858-4865.

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