Preparation Of Alachlor And Acetochlor Release Formulation And Study On Adsorption And Realease

Controlled release formulations that were deemed to be safe,rational,economic and effective within field of employment were ideal formulations.Research of sustained-release materials that aimed to exploit low cost and excellent regulative capacity of release rate for high water-soluble pesticides was an important topic in the domain of research of controlled release formulations.In this paper,organobentonite,prepared by employing octadecyl trimethyl ammonium chloride(OTMAC),dodecyl trimethyl ammonium chloride(DTMAC)and cetyl trimethyl ammonium chloride(HTMAC)as modifying agents,was used as carrier to obtain different loading levels of alachlor and acetochlor controlled release granule.The structure of organobentonite was also investigated by X-ray diffraction(XRD)?Fourier transform infrared spectroscopy(FTIR)and thermal analysis(DTG-TG).The adsorption kinetics,equilibrium isotherm on the organic bentonite and controlled release of alachlor and acetochlor have been studied.The main conclusions of this work are as follows:1.Organobentonite was found to be modified successly by XRD,FTIR and TG analysis.OTMAC-bentonite inserted the bentonite layer in the form of single-layer tiles mainly.Increasing loading of DTMAC and HTMAC into bentonite can increase interlayer spacing.DTMAC-bentonite arrangement in the layer of bentonite changed from monolayer to bilayer tile.HTMAC-bentonite arrangement in bentonite changed from single tile transition to double tile to fake three layers of tile.2.Adsorption kinetics experiments showed that the adsorption of acetochlor and alachlor on the organobentonite is a fast process.The experimental datas werea fitted with pseudo-first order equation,pseudo-two order equation and particle diffusion equation.It was found that the adsorption process was in accordance with the pseudo-two equation and the correlation coefficient was above 0.99.The results showed that two steps occurred mainly in the whole process.The external surface adsorption(stage 1)was the fastest and the initial rate of adsorption was greater for higher loading and longer carbon chain of modifiers.Then the stage of intraparticle diffusion control(stage 2)is attained and the rate of adsorption was decreased with increasing loading and carbon chain of modifiers.3.Equilibrium isothermal adsorption experiments showed that the adsorption capacity increased with the increasing of the loading of the modifiers.When the loading reaches about 1.0CEC,the increase of the adsorption capacity is not obvious.In addition,The length of carbon chain is the main factor affecting the adsorption capacity.The longer the carbon chain,the greater the adsorption capacity.4.The release experiments showed that Fickian diffusion is the main ways of release and the release of the herbicides could be effectively delayed by the use of organic modified bentonite as carrier.The release rate was mainly influenced by the adsorption properties,the length of the carbon chain and the internal structure of the organic modified bentonite.The results indicated that the time taken for 50%of active ingredient to be released(T50)from acetochlor and alachlor,modified by organobentonites with HTMA loading of 100%of the cation exchange capacity,were 35 and 85 times,respectively.