Vol 51, No 1 (2017)

The functional group composition, spectroluminescent properties, and catalytic effect of humic acids isolated from coals were studied. The constants of the complexation of humic acids with cadmium ions were determined by a fluorescence quenching method.

The effect of the preheating rate of the char particles from Kuznetsk bituminous coal on their specific reaction rate was determined. The experiments were carried out with char samples with mean diameters of 0.15 and 0.35 mm heated to temperatures of 900–1000°C. It was found that the specific surface area of the initial coal, measured by CO₂ adsorption at 273 K, for rapid and slow heat treatments increased more that two times. According to the results of thermogravimetric analysis, it was established that rapid pyrolysis in a muffle furnace led to the production of char whose maximum specific reaction rate was higher than that of the samples after slow pyrolysis.

The effect of mechanochemical activation and microgrinding on the intensity of combustion of solid fuel particles was studied. As applied to the rapid process of the combustion of solid fuel particles, mechanochemical activation was simulated within the framework of nonequilibrium thermodynamics with the expansion of the classical dependence of the local entropy of state of the reacting system on relaxation phenomena. The dependences of the intensity of burning (mass loss time) of deformed organic solid fuel particles on the relaxation processes of the momentum transfer of their excited states and on the mutual orientation of shear stresses and the first difference in normal stresses (a steric factor), which compensate for temperature power consumption, were established. The rate of combustion is determined by the size of burning particles, their density, and a ratio between the elastic and dissipative scattering of mechanical energy in the particles, which increases the diffusion mobility of burning components with a decrease in the time of their burning. The ranges of variation in the parameters of the burning system in which the particle size or mechanoactivation exerts a considerable effect on the combustion time of fuel particles were recognized. Experiments on the torch combustion of coal-dust fuel as the cumulative combustion of its particles confirmed the effect of mechanoactivation.

The kinetics of adsorption of ethyl benzoate from solutions in ethanol on coconut shell activated carbon was studied. It was found that the kinetics of adsorption of ethyl benzoate can be described by pseudofirst-order and pseudo-second-order rate equations with the same accuracy. It was established that the adsorption isotherm at a concentration to 2 g/L in the initial solution is adequately described by the Langmuir equation.

Conditions for the solid-phase mechanochemical activation of coals, which make it possible to substantially increase the yield of water-soluble humic preparations enriched in humic acids and mineral elements, are given in this work. It was found that the humic preparations isolated from mechanically activated coals are characterized by an increase in the antioxidant activity and a change in the cationic and anionic composition. The concentration of acidic ionogenic groups in humic acids increased.