Preparation And Property Of Lignin Based Slow/Controlled Release Pesticide

The authors gratefully appreciate the financial support from the National Natural Science Foundation of China (No.30901135), the State Forestry Administration Industry Public Welfare Projects (No.20120480306) and the "12th Five Year" in national science and technology for the rural development (No.2012BAD24B0403). The using of slow-release formulation of pesticide is an effective strategy to reduce environmental pollution. However, the high cost hampers the widespread applications of slow-release formulation of pesticide. The source of industrial alkali lignin is widespread and low cost. However, its utilization rate is low. So a slow-release formulation of pesticide was prepared with lignin as raw material, reducing the cost of the preparation, and industrial alkali lignin could be better used. In order to a slow-release formulation of low cost and of release regulation capability, two kinds of slow-release formulation of pesticide were prepared with industrial alkali lignin, sodium-based bentonite and polyvinyl alcohol (PVA) as raw material in this paper. The research results were as follows:Bentonite loading different lignin quaternary ammonium salt was synthesized through metal ion exchange of the layers of bentonite, sodium-based bentonite as a raw material, as the modification agent was L-QA and DBSLAC, respectively. Hymexazol and Acetaniprid were selected as the drug for release, and were loaded on modified bentonite, respectively. Pesticide slow release formulation was prepared by means of adsorption, and its performance was studied with the method of water solving. The structure of modified bentonite was analyzed by FT-IR. The basal spacing of modified bentonite was analyzed with XRD, and the particle size was analyzed with laser particle analyzer.The modification agent was L-QA, and the process conditions were determined by single-factor test. The optimum preparation conditions of hymexazol slow-release formulation were L-0.8Bt dosage 0.06 g, adsorption time 10 h, mass concentration of hymexazol 500 mg/L and pH 4, which the maximum adsorption capacity was 281 mg/g. The optimum preparation conditions for acetaniprid slow-release formulation were L-0.8Bt dosage 0.02 g, adsorption time 4 h, mass concentration of acetaniprid 500 mg/L and pH 6, which the maximum adsorption capacity was 315 mg/g.The modification agent was DBSLAC, and the process conditions were determined by single-factor test. The optimum preparation conditions of hymexazol slow-release formulation were L-1.2Bt dosage 0.02 g, adsorption time 8 h, mass concentration of hymexazol 500 mg/L and pH 2, which the maximum adsorption capacity was 406 mg/g. The optimum preparation conditions for acetaniprid slow-release formulation were L-1.2Bt dosage 0.02 g, adsorption time 6 h, mass concentration of acetaniprid 500 mg/L and pH 6, which the maximum adsorption capacity was 333 mg/g.With alkali lignin (AL) and PVA as raw material, glyoxal as crosslinker, alkali lignin crosslinking PVA blended slow-release pesticide flim was prepared by tape casting. The chemical structure of the flim was characterized by FT-IR. The gas permeability and mechanical properties were characterized. The results showed that alkali lignin had been crosslinked with PVA successfully. Compared with no pesticide crosslinked film, oxygen transmission and carbon dioxide transmission of pesticide slow-release film reduced. Its tensile strength and elongation at break reduced. The optimum preparation conditions of hymexazol slow-release film were the mass ratio of AL and PVA 4:6, glyoxal dosage 2.0 mL and hymexazol dosage 0.8 g. The optimum preparation conditions of acetaniprid slow-release film were the mass ratio of AL and PVA 3:7, glyoxal dosage 1.5 mL and acetaniprid dosage 0.5 g.The slow release performance of the product prepared under the optimum condition was determined by the water soluble method. The result could prove that with the increase of potion proportion, the accumulative release rate of drug was graually increased. We could select different potion proportion to spray, when the plant encountered in different levels of disease. With the increase of temperature, the accumulative release rate of drug-loaded product was graually increased. This is suggesting that the potion proportion and temperature had an effect on the slow release speed of drug-loaded product.