Olena Goncharuk

Nanosized Oxides of Different Compositions as Adsorbents for Hazardous Substances Removal from Aqueous Solutions and Wastewaters

Adsorption methods are considered to be highly effective in the industrial effluents treatment technologies. Preparation of cheap and selective adsorbents with significant sorption capacity is a serious challenge for scientists. Nanosized mixed oxides have been successfully used for removal of environmental contaminations from aqueous streams. Taking into account the morphological and microstructural properties of the nanosized oxides, mechanical strength and non-toxicity in many cases, these materials are popular. The literature review concerning removal of metal ions, dyes and polymers using nanosized single and mixed oxides was made. The adsorption parameters which affect removal efficiency, i.e. concentration, phase contact time as well as equilibrium and thermodynamic aspects, were taken into account.

Effect of Ethonium Adsorption on Structure Formation in Nanosilica Dispersions

Adsorption of ethonium on silica surface strongly affects the particle size distribution, stability and rheological properties of aqueous dispersions of fumed silica. The Sshape of isotherm of ethonium adsorption on nanosilica suggests the multilayer adsorption. The adsorption of ethonium leads to changes in the shape of the pHdependence of the zeta-potential and a significant increase in the particle sizes in the aqueous dispersions of silica. A marked increase in the colloidal stability is observed for the dispersions at silica concentration of 5 wt.%, while for 1 wt.% dispersions the ethonium presence almost does not affect the stability. The rheological properties of the dispersions depend on the ethonium concentration, and the maximum values of the viscosity and rheopectic behavior are observed at ethonium concentration of 0.1-0.3 wt.%

Wettability and thermal analysis of hydrophobic poly(methyl methacrylate)/silica nanocomposites

Hydrophobic poly(methyl methacrylate)/silica layers on the glass support activated with plasma were obtained. Wettability was investigated from the contact angle measurements and surface free energy estimation by means of using contact angle hysteresis approach. The thermal analysis of poly(methyl methacrylate)/silica films was conducted on a STA 449 Jupiter F1, Netzsch in temperature range of 30–950℃. It was found that the thermal stability of the poly(methyl methacrylate)/silica films decreases with increasing poly(methyl methacrylate) amount in the sample. Morphology of the obtained nanocomposites was investigated by means of scanning electron microscopy. The addition of silanized silica to the poly(methyl methacrylate) solution leads to obtaining the film with more hydrophobic properties, the contact angle value over 90°, and the apparent surface free energy lower than 30 mJ/m2. The most hydrophobic film was obtained in the case of silica with Θ = 0.63 (Θ – surface fraction coverage with trimethylsilyl groups). Silica particles were well dispersed in the polymer solution which was confirmed by the scanning electron microscopy analysis.