Preparation and characterization of slow release zeolite based fertilizer

In this study, a slow release zeolite-based fertilizer was prepared using ammonium nitrate fertilizer, which is frequently used in plant nutrition because it is very beneficial for plants, and zeolite mineral, which has high reserves in our country, is cheap, easy to access, nontoxic, and is generally used as a soil conditioner in agriculture. Natural zeolite was obtained from the Manisa Gördes region, and its chemical and mineral structure was elucidated by TGA/DTA, FTIR, BET, XRD, SEM-EDS, and ICP-OES characterization techniques. According to the ICP-OES results, the Si/Al ratio of the zeolite was 4.78, according to the SEM-EDS analysis results, the Si/Al ratio was 4.50 and according to the XRD analysis results, the Si/Al ratio was 4.90. These results showed that the natural zeolite type is clinoptilolite and contains sanidin and quartz impurities. In the zeolite fertilizer obtained by using natural zeolite and ammonium nitrate, the number of washings after preparation, different zeolite:ammonium nitrate solid:solid ratios, application temperature, reaction time, and different size parameters of the zeolite were investigated within the scope of optimization studies. Optimum zeolite fertilizer was obtained using 0-200 µm zeolite size, at a 1:4 zeolite:ammonium nitrate solid:solid ratio at 200 °C for eight hours synthesis time. According to the results of the elemental nitrogen analysis of the zeolite fertilizer obtained under optimal conditions, the %N content was determined as 5.06%. The characterization of the zeolite fertilizer was made by TGA/DTA, FTIR, BET, XRD, and SEM-EDS techniques as in natural zeolite, and its slow release at 15 days in water was investigated. The adsorption of ammonium nitrate to natural zeolite did not significantly change the zeolite structure, the structure lost more mass than natural zeolite in the TGA analysis, the presence of nitrate peaks in the FTIR analysis, and the crystal structure of the zeolite was preserved according to the result of XRD analysis. According to BET analysis, the adsorption of ammonium nitrate decreased the surface area of the zeolite fertilizer and it was determined that the structure aggregated in the SEM images. The NO3⎺ and NH4+ ions released from the structure of the zeolite fertilizer into the water during the slow release of 15-days were determined by the IC device. The characterization of the zeolite fertilizer after slow release was performed with TGA/DTA, FTIR, BET, XRD, and SEM-EDS techniques as in the natural zeolite and zeolite fertilizer, so that changes occurring according to the natural zeolite and zeolite fertilizer could be observed. The% N content of zeolite fertilizer after slow release was determined to be 1.58%, the mass loss in TGA analysis decreased compared to zeolite fertilizer, and nitrate peaks were observed to disappear in FTIR analysis. The BET surface area increased again as it released the ions in its structure compared to the zeolite fertilizer, and it was observed in the SEM images that the structure again took on an appearance close to the natural zeolite images. According to XRD analysis and EDS chemical analysis, the amounts of other elements, except for the N element, in zeolite fertilizer after slow release are similar to natural zeolite and zeolite fertilizer. According to the results of the detailed analysis of the characterization, the information obtained is compatible with each other, and the obtained zeolite fertilizer was slow release and slow release continued until the 15th day. The zeolite fertilizer obtained by this method is believed to be used as a slow-release zeolite fertilizer, which can be commercialized and can be included in integrated fertilization programs to increase plant yield.