[Objective] The aim of this study was to discuss the optimizing preparation conditions of polyvinyl alcohol(PVA)hollow microsphere and its application in the production of slow-release urea fertilizer.[Method]PVA hollow microsphere was prepared by the emulsion chemical cross-linking method,while its composition,morphology and particle size was analyzed by technologies of FT-IR,SEM and TEM respectively.Thus,factors such as rate of emulsified speed,crosslink temperature and linking agent amount with effects on morphology and particle size of hollow microsphere were also discussed in this study.Furthermore,based on the optimizing preparation conditions,PVA fertilizer carrier microsphere was prepared by coating urea to investigate its sustained release effect on urea.[Result]The optimizing preparation conditions of polyvinyl alcohol(PVA)hollow microsphere were as follows:rate of emulsified speed 6 000 r/min,crosslink temperature 35 ℃ and linking agent amount 25 ml.PVA fertilizer carrier microsphere had significant sustained release effect on urea,and the optimal cross-linking time was 3 hours.[Conclusion]This study provides theoretical basis for the development of new slow-release fertilizer.
In common sense,the chemical reaction between Cu2+ and S2-ions produces black precipitation of CuS.However,if they are separated by an eggshell,they produce copper with trace amount of CuS on the surface of the eggshell at the side of copper chloride solution within one week.Such an unexpected phenomenon strongly indicated that Cu2+ is able to be reduced into metal copper when S2-diffuses throughout the porous eggshell.The produced copper was verified by reacting with nitric acid to generate red-brown nitrogen dioxide at ambient temperature,as well as by the powder X-ray diffraction(XRD) and energy dispersive analysis of X-rays(EDS).
ZHANG WenLi WANG Zhao SHAO Bing NI Liang QIU Lin QIU Shu
