Preparation And Study On Release Properties Of Thiamethoxam Sustained-release Granules

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-Active ingredients were embedded by macromolecule matrix,which is a significant controlled release formulations preparation technology.Biodegradable macromolecule materials of sodium alginate and polylactic acid were usually applied to controlled release matrix.Excessively fast or slow release rates were obtained by only using sodium alginate,ploylactic acid respectively.Therefore,release rate of active ingredients was modulated hard.High water-soluble pesticides thiamethoxam was used as model drug.Organobentonites of different modifying agent loaded were modified by Octyl trimethyl ammonium chloride(OTMAC),Dodecyl trimethyl ammonium chloride(DTMAC)and Hexadecyl trimethyl ammonium chloride(HTMAC)respectively.Thiamethoxam sustained-release granules were manufactured by embedding thiamethoxam into composite sustained-release materials mixed organobentonites with sodium alginate or polylactic acid.Organobentonites structure were studied by Fourier Transform Infrared Spectroscopy(FTIR)and X-ray diffractometer(XRD).Effects on organobentonites structure for sorption ability and thiamethoxam release from sustained-release granules were investigated.Main results as followed:(1)Sorption experiments revealed that organobentonites did not show higher adsorption of thiamethoxam.Adsorption capacity of organobentonites was enhanced by lengthening alkyl chain of quaternary ammonium.Surface adsorption was dominant function for organobentonites that modified by short alkyl chain of quaternary ammonium.Distribution function played an important role on adsorption of organobentonites that modified by long alkyl chain of quaternary ammonium.(2)The results showed that thiamethoxam release was delayed by adding organobentonites onto matrix of sodium alginate.Thiamethoxam release rates from sustained-release granules based on sodium alginate as matrix were independent of amount of additive organobentonites.Increased the alkyl chain of quaternary ammonium,thiamethoxam release rates were decreased on low modifying agents loaded,but thiamethoxam release rates were increased and then reduced on high modifying agents loaded.Thiamethoxan release was dominantly governed by adsorption capacity and interlamination distance of organobentonites.Release rates could be decreased by organobentonites with excellent adsorption capacity and small interlamination distance.(3)The results indicated that thiamethoxam release was boosted by adding organobentonites onto matrix of polylactic acid.Release rates were further enhanced by increasing content of organobentonites.Added organobentonites that were modified by long alkyl chain of quatermary ammonium,thiamethoxam release rates were reduced.Thiamethoxan release from sustained-release granules based on polylactic acid as matrix was related to hydrophobic and interlamination distance of organobentonites.Release speed was boosted by weak hydrophobic and large interlamination distance of organobentonites.Release speed of thiamethoxam will be modulated by selected to adding different organobentonites.Compared with experiment results of two kinds of sustained-release granules,polylactic acid was superior to sodium alginate as sustained-release materials of thiamethoxam.