In this work, adsorption of rhodamine B (RB) and acid yellow 17 (AY17) was investigated on ordered mesoporous carbon material obtained by soft-templating method with hydrochloric acid (ST-A). For comparison, the adsorption process on commercial activated carbon CWZ-22 was also carried out. The sorbents were characterized by nitrogen adsorption/desorption isotherms and scanning electron microscopy. Langmuir and Freundlich adsorption isotherm models were applied to simulate the equilibrium data of RB and AY17. Adsorption isotherm data could be better described by the Langmuir model than the Freundlich model. The adsorption kinetics of RB and AY17 on studied carbons could be well depicted by using pseudo-second-order kinetic modeling. The adsorption capacity increased with temperature increase in the range of 298–315 K. In the whole diffusion process, the intraparticle diffusion was involved, but not the whole rate-controlling step. The calculated thermodynamic parameters, including Gibbs free energy (∆G), enthalpy (∆H), and entropy (ΔS) suggested that adsorption processes of RB and AY17 on ST-A and CWZ-22 were endothermic and spontaneous.

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The kinetics of photocatalytic degradation of aniline, 2-chloroaniline, and 2,6-dichloroaniline in the presence of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites, halloysite containing naturally dispersed TiO2, Fe2O3, commercial TiO2, P25, and α-Fe2O3 photocatalysts, were investigated with two approaches: the Langmuir–Hinshelwood and first-order equations. Adsorption equilibrium constants and adsorption enthalpies, photodegradation rate constants, and activation energies for photocatalytic degradation were calculated for all studied amines photodegradation. The photodegradation mechanism was proposed according to organic intermediates identified by mass spectrometry and electrophoresis methods. Based on experimental results, it can be concluded that after 300 min of irradiation, aniline, 2-chloro-, and 2,6-dichloroaniline were completely degraded in the presence of used photocatalysts. Research results allowed us to conclude that higher adsorption capacity and immobilization of TiO2 and Fe2O3 on the halloysite surface in the case of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites significantly increases photocatalytic activity of these materials in comparison to the commercial photocatalyst: TiO2, Fe2O3, and P25.

Soils, next to vegetation, are one of the most popular indicators in environmental quality studies. The response of soils to air pollution is less complex than the response of vegetation. In soils, mainly in their upper layers, the deposition of compounds may occur almost undisturbed, therefore results of chemical analyses are readily used in the assessment of changes caused by natural processes and anthropogenic activities. In a temperate climate zone, the outermost layer of forest soils is formed by an organic horizon (-O), which comprises two basic subhorizons, of which the organic fermentative-humic subhorizon (-Ofh) is recognized as the most noteworthy. The subhorizon-Ofh encompasses partially and fully decomposed organic matter (humic and fulvic acids, humins), as well as Fe, Mn and Al oxides and hydroxides, forming a characteristic tangled mat. The structure pattern of this subhorizon is responsible for the higher concentrations of elements and organic compounds, which are immobilized through sorption, complexation or precipitation. Some previous studies have shown that the subhorizon-Ofh has enhanced accumulative properties in comparison to the remaining subjacent soil horizons. Results derived from soil studies in the Holy Cross Mountains/HCMs (south-central Poland) have also revealed that this subhorizon is mainly enriched in polycyclic aromatic compounds (PAHs) and some trace elements (Hg, Cd, Cu, Pb, Zn). This could make the subhorizon-Ofh a potential geoindicator of soil quality in relation to these compounds over the temperate climate zone. However, further study on this issue is needed to confirm its application in environmental monitoring.