Pergher, Sibele Berenice CastellaDiógenes, Larissa Castro2023-05-162023-05-162022-11-03DIÓGENES, Larissa Castro. Desenvolvimento de carreadores para fertilizantes a base de zeólita Lta e hidroxiapatita com liberação lenta de nitrogênio, fósforo e potássio. Orientador: Sibele Berenice Castellã Pergher. 2022. 141f. Tese (Doutorado em Química) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2022.https://repositorio.ufrn.br/handle/123456789/52426The 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.Acesso AbertoQuímicaFertilizantes de liberação lentaZeólitasArgilasCarreadores de potássioCompósitos-NPKdoctoralThesisCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA