The influence of Mn2+ and Ni2+ ions on the surface properties of the aluminium oxide samples using Q-TG and Q-DTG data

The paper presents the complex studies of adsorption and porosity of pure and modified–aluminium oxides samples. The presence of Mn²⁺ and Ni²⁺ modifiers on the aluminium oxide surface causes increase in water adsorption capacity and its decrease in the case of benzene and n-octane. This is due to decrease of specific surface area, volume and radius of pores as a result of surface impregnation and microcrystals formation during modification with manganese and nickel chlorides. Microcrystals formation on the surface and porosity decrease where confirmed by the AFM and SEM studies. From the Q-TG and Q-DTG data, the energies of liquid desorption from the surface of the samples and the functions of desorption, energy distribution were calculated. High degree of nonlinearity of the run of the functions resulting from great heterogeneity of the studied surface was found. Adsorption of cations creates more homogeneous surface of aluminium oxide, and it is responsible for the change in adsorbate molecule interaction energy and changes mechanism of adsorption and desorption as well as thickness and structure of the adsorbed film. From the experimental data some parameters characterizing adsorption properties and porosity of the studied samples were determined using the measuring methods (thermal analysis, sorptomate, porosimetry, AFM).