Article ID Journal Published Year Pages File Type
9693933 Thermochimica Acta 2005 5 Pages PDF
Abstract
Zinc hydroxide carbonate precursor, Zn4CO3(OH)6·H2O, was synthesized from zinc sulfate using ammonium carbonate as a precipitating agent. Thermogravimetry (TG), differential scanning calorimetry (DSC), transmission electronic microscopy (TEM), infrared spectrum (IR) and X-ray diffraction (XRD) were used to characterize the precursor and the decomposed product. Non-isothermal kinetics of the thermal decomposition of zinc hydroxide carbonate were studied in nitrogen. Based on which, the kinetic parameters were obtained through mode-free method and the thermal decomposition mechanism was derived by mains of non-linear regression. The results show that the decomposition of zinc hydroxide carbonate acts as a double-step reaction, A⟷D2B⟶FnC: a reversible reaction of two-dimensional diffusion (D2), with E1 = 202 kJ mol−1, lg(A1/s−1) = 22.1, is followed by an irreversible one of nth-order reaction (Fn) with n = 0.51, E2 = 129 kJ mol−1, lg(A2/s−1) = 10.5, and the decomposition of Zn4CO3(OH)6·H2O to ZnO is accompanied by the change in particle morphology and particle size.
Related Topics
Physical Sciences and Engineering Chemical Engineering Fluid Flow and Transfer Processes
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