Desenvolvimento de carreadores para fertilizantes a base de zeólita Lta e hidroxiapatita com liberação lenta de nitrogênio, fósforo e potássio
The present work describes the development of composite materials to be used as slowrelease fertilizers. To obtain these composite materials, bentonite and illite clays, LTA zeolites and clinoptilolite were tested as potassium carriers. The materials were characterized by X-ray diffraction (XRD),...
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| 格式: | doctoralThesis |
| 语言: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| 在线阅读: | https://repositorio.ufrn.br/handle/123456789/52426 |
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| 总结: | The present work describes the development of composite materials to be used as slowrelease fertilizers. To obtain these composite materials, bentonite and illite clays, LTA
zeolites and clinoptilolite were tested as potassium carriers. The materials were
characterized by X-ray diffraction (XRD), X-ray fluorescence (FRX), Fourier transform
infrared spectroscopy (FTIR), the leached potassium content in soil columns was
determined by atomic emission spectrometry with inductively coupled plasma
(ICP-OES). Among the materials tested, the LTA zeolite was the one that presented the
best potassium adsorption capacity with a slow and gradual release behavior, which are
desirable characteristics for slow-release fertilizers. Zeolite LTA was also exchanged
with KOH solutions of different concentrations and different times. In this process, the
KOH concentration exerts a greater influence on the K+ adsorption capacity by the LTA
zeolite than the time used in the cation exchange process. Considering the good
performance of the LTA zeolite as a K+ ion carrier in the soil and its high K+ adsorption
capacity, this material was chosen for the formulation of the composites. The composites
were prepared with LTA zeolite, urea, and hydroxyapatite, which is a calcium phosphate
that presents excellent biocompatibility and a specific area that allows the connection
with urea molecules. The composites were synthesized through precipitation reactions of
phosphate ions in suspension of calcium hydroxide with urea and LTA zeolite and
characterized by XRD, FRX, FTIR and scanning electron microscopy (SEM-FEG). XRD
analysis with Rietveld refinement confirmed that the composite samples have
hydroxyapatite in their composition. In the samples identified as HUZ and ZHU, the
hydroxyapatite present is found in two phases, monoclinic and hexagonal. In the other
two composite samples Z3AUH2 and HAZ3AU, hydroxyapatite is present only in the
monoclinic phase. The presence of phases referring to hydroxyapatite, Zeolite LTA and
urea are also confirmed by FTIR and SEM results. The SEM images show hydroxyapatite
crystals with urea in the form of rods lining the cubic surface of the LTA zeolite. The best
results were obtained by preparing a composite material based on Zeolite LTA,
hydroxyapatite, and urea, for use as a slow-release fertilizer for soil nutrients. |
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