Synthesis, characterization, and catalytic behaviour of nano-bimetallic nickel oxide on the thermal decomposition of dihydroxylammonium-5,5 0 -bistetrazole-1,1 0 -diolate)Bimetal combustion catalyst has become an emerging field in recent years, which is still in its infancy. When the combustion catalyst is used in double-base propellants, it can produce effects that conventional catalysts cannot achieve. In this study, nano-bimetallic nickel oxides (nanospheres of NiFe 2 O 4 and the sub-nanometre flower NiCo 2 O 4 ) were prepared by hydrothermal method and characterized using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and N2 adsorption-desorption test (BET). Moreover, its thermal catalytic action on dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) was studied. The thermal analysis of composite TKX-50/NiFe 2 O 4 and TKX-50/NiCo 2 O 4 was carried out by thermogravimetric differential scanning calorimetry (TG-DSC). The results show that when the addition amount of NiFe2O4 is 10%, the heating rate is 5.0 K min −1 , the NiFe 2 O 4 has the best catalytic activity for TKX-50 thermal decomposition, and the high thermal decomposition peak temperature (Tpeak1) is decreased by 29 °C. More interestingly, the apparent activation energies of the two composites were calculated by Kissinger, Ozawa, and Starink methods. The advanced thermal analysis kinetics software (AKTS) was used to perform kinetic calculations on the DSC experimental curves of the abovementioned composite energetic materials, and reaction rate curves obtained by the simulation are in good agreement with the experimental curves of the thermal decomposition reaction process, further proving that the accuracy of the experiment is high. Therefore, the addition of NiFe 2 O 4 shows high catalytic efficiency on the thermal decomposition of TKX-50 components, and this would be beneficial to promote the burning rate of propellants containing TKX-50 components.
This study investigated the inhibition effects of sulfate on ferrous ion-activated persulfate oxidation of azo dye reactive brilliant red X-3B. The experimental results showed that the degradation efficiency of reactive brilliant red X-3B decreased from 100% to 63% in 60 min when the initial concentration of sulfate increased from 0 to 3 g/L. The ferrous/persulfate molar ratio had remarkable influence on persulfate oxidation capability in presence of sulfate. SO42− could coordinate with Fe2+ and Fe3+ in generating FeSO4 ion pairs as well as FeSO4+ or Fe(SO4)2− complexes, which were difficult to activate persulfate and reduced the regeneration of Fe2+. Radicals quenching and electron paramagnetic resonance experiments showed that ·OH and SO4·− were responsible for the oxidation of reactive brilliant red X-3B; however, the addition of sulfate significantly inhibited the generation of SO4·−, and then the generation of ·OH. Moreover, the corresponding Nernst equation indicated that high concentration of sulfate reduced the oxidation potential of SO4·−/SO42−. Experimental results proved that the adverse effects of sulfate on the persulfate oxidation could be counteracted either by batch addition of ferrous or by adding Ba2+ to remove SO42− in the system.
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