The sorption properties of two layered minerals of the hydrotalcite supergroup – hydrotalcite and stichtite – were investigated with the aim of determining their kinetic parameters of sorption and their adsorption isotherm type. Pristine hydrotalcite and stichtite were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive Х-ray analysis and laser diffraction analysis of the particle-size distribution. The ‘memory effect’ of the sorbents was examined after calcination at 650°C. Slight indications of reconstructed hydrotalcite were observed, while the stichtite dehydration–rehydration cycle was irreversible. The hydrotalcite and stichtite were used to remove Congo Red from the aqueous solution. The pseudo-second order kinetic model described the process adequately. Mixed external and internal diffusion was confirmed for both minerals. The sorption of Congo Red on stichtite fits the Langmuir model. Stichtite demonstrated a maximum adsorption capacity of 2.5 mmol g–1 at 35°C. Increasing temperature increased the adsorption rate of Congo Red on stichtite but did not affect the adsorption rate constant for hydrotalcite.

The influence of hydrogen on the growth of carbon nanostructures in thermal chemical vapor deposition is studied using density functional theory calculations. It is shown that hydrogen adatoms effectively bind to edges of graphitic structures on the Ni (111) surface. This is found to result in a significant decrease of the rate of carbon attachment to the growing graphitic structures. However, it is also demonstrated that the edges of graphitic structures which are attached to steps on the Ni surface should not be hydrogenated.