Abstract: The thiosulfate anion (S₂O₃^2-) was intercalated into a ZnAl layered double hydroxide (LDH), and its oxidation reaction with hexacyanoferrate(III) (Fe(CN)₆^3-) in the confined region between the layers of LDH has been discussed. Based measurements of the intermediate state and final product using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the oxidation product tetrathionate (S4O₆^2-) dissolved in solution, while the reduction product hexacyanoferrate (II) existed in the interlayer of the LDH. Furthermore, the kinetics of this reaction were investigated in batch mode. The influences of the initial Fe(CN)₆^3- concentration, ZnAl-S₂O₃ LDH quantity, and reaction temperature on the oxidation reaction were studied. The reaction follows a diffusion-controlled process represented by Crank-Ginstling and Brounstein model with the apparent activation energy of 24.6 kJ·mol^-1, which was about 13.7 kJ·mol^-1 less than that of the solution reaction under the same conditions. The influence of water content on interlayer spacing was simulated by molecular dynamics. The simulation result shows that the size of this microreactor can be regulated in a certain orientation in the solution environment. From the experimental results and theoretical calculation, we propose a mechanism for the interlayer reaction. This layered material can be used as a novel nano-reactor to regulate the rate of chemical reactions.

Key words: Kinetics, Thiosulfate, Hexacyanoferrate(III), Interlayer reaction, Reaction mechanism