| In recent years, with the improvement of environment awareness and protection,pesticide is developed in the direction of high-efficiency and environmentally friendly.Suspension concentrate (SC) not only has the advantages of emulsifiable concentrate (EC)and wettable powder (WP), but also has no solvent pollution during the preparation. SC hasbecome “epoch-making” pesticide formulation. However, the physical stability of SC is poordue to the problems of sediment and agglomeration during long-term storage. Therefore, thedispersant of SC is mainly expenxive polycarboxylate. Lignin, the second abundant biomassresources, is completely biodegradable, nearly non-toxic and harmless. Lignin dispersant hasbeen used in the pesticide formulation. However, utilization of lignin dispersant is not sopopular in the field of SC because of some limitations. As a result, it is necessary to develophigh-efficient lignin dispersant to reduce the cost and promote the application of SC.In this thesis, effects of four lignin dispersants (ELSMN, GCL4-1, GCL4-2andGCL4-CM) on SC’s application performance were studied, with the aim of choosingexcellent lignin dispersants to enrich the variety of efficient dispersants. The influence oflignin dispersants’ structures on their adsorption amount were explored, to provide theoreticalguidance for the development of high-efficient lignin dispersants.New formulation of43%tebuconazole SC was studied. The results showed that theapplication performance of43%tebuconazole SC was perfect with a dosage of3%ELSMNand0.08%xanthan gum, respectively. Meanwhile, new formulation of35%imidacloprid SCwas also studied. The application performance of35%imidacloprid SC was perfect with adosage of3%GCL4-1, or with a dosage of4%GCL4-2and0.15%xanthan gum, respectively.The SC formulations had met the requirements of national standard GB29381-2012. Theresults showed that ELSMN, GCl4-1and GCL4-2were suitable for the preparation of SC.The structures of four kinds of lignin-based dispersants were characterized, and thehydrophilicities were investigated by measuring the contact angles of water on lignin films.Meanwhile, the effect of lignin-based dispersant’s hydrophilicity on the adsorptionperformance was investigated. The results showed that hydrophilicity was closely related tothe molecular weight, hydrophilic group and its content. Lignin dispersant with biggermolecular weight had better hydrophilicity, while higher hydrophilic group content wouldhelp to improve its hydrophilicity. Different lignin dispersants had different absorptionperformances on high hydrophobic tebuconazole. Adsorption amounts of medium hydrophilicGCL4-1and GCL4-CM on tebuconazole were larger than the absorption amounts of GCL4-2 with most hydrophilicity and ELSMN with least hydrophilicity. It was not true that thedispersant with less hydrophilicity absorbed more on the surface of hydrophobic pesticide.There would be better interaction between dispersant and pesticide only when theirhydrophilicity and hydrophobicility match well.The effect of pH, NaCl, temperature and urea on adsorption amount were furtherexplored. The result showed that the maximum adsorption amount of lignin dispersants ontebuconazole increased with the decrease of pH or the increase of temperature. The additionof NaCl helps to increase adsorption amount of lignin dispersants on tebuconazole. While themaximum adsorption amount of lignin dispersants on tebuconazole decreased with theaddition of urea, it indicated that there was hydrogen bonding. The Zeta potential of lignindispersants on tebuconazole particles at different pH was investigated. The Zeta potential oflignin dispersants on tebuconazole decreased as pH reduced. At pH8, the Zeta potential oflignin dispersants on tebuconazole is GCL4-CM> GCL4-1> ELSMN> GCL4-2.The results showed that ELSMN has the best application performance in tebuconazoleSC, while ELSMN did not have the largest adsorption capacity and zeta potential, which isprobably because ELSMN has larger molecular weight and volume, and easily form largerspace steric effect. In follow study, the thickness of adsorption layer need to be furtherinvestigated. |
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