Layered double hydroxides can be widely applied as catalysts, catalyst precursors, ion exchangers, adsorbents materials, among others. Those minerals can be found in nature, but can be synthesized in the laboratory as well. Therefore, many researches has been done to improve the conditions of synthesis of these compounds. This work proposes to synthesize two types of LDH, Zn,Cu-Al-CO3 System and Zn-Al (CO3) In order to evaluate the effects of various reaction parameters: hydrothermal bath time and molar ratio (M2+∕M3+), in the optimization of the synthesis process. The samples were synthesized by the coprecipitation method, 11≤pH≤13, and thermal treatment with 80ºC. The characterization of the samples was carried out through XRD, SEM, IR and DTA-TGA. The first experiment was related to Zn,Cu-Al (CO3) LDH system, wherein the predetermined variable was the molar ratio (0,25 to 1,5), In the second experiment we used the best result of the previous experiment, which in turn had as variable the hydrothermal bath time (1 to 3 days). The third experiment was related to the HDLs in the Zn-Al (CO3) system wherein the predetermined variable is, like the first one, the molar ratio (0,5 a 3), in order to determine the best reason (M2+∕M3+) for the synthesis of LDH. The XRD patterns of the formed LDH indicated good crystallization, with sharp and intense peaks. The network parameters a=b=3,072Å, c=22,62Å, V=184,87Å, were similar to mineral reference values of the Carbonate Hydroxide, Cu, Zn and Al hydrated. There was a formation of two parallel stages in both systems; aluminum hydroxide and zinc oxide. In the LDHs of the Zn-Al(CO3) system, There was also the presence of two phases: aluminum hydroxide and zinc oxide. The micrographs showed well-formed crystals (≤2 μm) in the best results, was observed hexagonal habit that is typical of LDH. In the IR spectra was possible to verify the presence of 7 bands like: 3420,3046,1632,1359,959,792,609,551 and 427cm1- attributed to stretch links of OH, symmetry of CO32-, interlayer water, metal-O links and lamellar OH, respectively. The results of DTA-TGA exhibited 3-4 endothermic peaks in the second experiment, com perda de massa total entre 8,3 a 12,24%. In the two best results of the third experiment, the samples showed 4 endotherms and similar mass losses (9,04 e 8,1%).
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