• OLENA ORANSKA

      Articles written in Bulletin of Materials Science

    • Silica-supported Ni$_x$O$_y$, Zn$_x$O$_y$ and Mn$_x$O$_y$ nanocomposites: physicochemical characteristics and interactions with water and $n$-decane

      OLENA GONCHARUK VIKTOR BOGATYROV OLGA KAZAKOVA MARIA GALABURDA OLENA ORANSKA EWA SKWAREK HALINA WANIAK-NOWICKA WŁADYSŁAW JANUSZ VOLODYMYR GUN’KO

      More Details Abstract Fulltext PDF

      A series of M$_x$O$_y$/SiO$_2$ (where M $=$ Ni, Zn and Mn) nanocomposites were synthesized at different M$_x$O$_y$ contents (0.2, 1 and 3 mmol per 1 g SiO$_2$) using a deposition method. The samples were characterized using nitrogen adsorption–desorption, X-ray diffraction, Fourier transform infrared spectroscopy, high resolution transmission electronmicroscopy and photon correlation spectroscopy. The heat of immersion in water ($Q_w$) and $n$-decane ($Q_d$) were measured using a microcalorimetry method, and the corresponding values of the hydrophilicity index $K_h = Q_w/Q_d$ were analysed.The formation of M$_x$O$_y$ on a silica surface leads to diminishing of the $Q_w$ and $Q_d$ values (calculated per 1 g of nanocomposites) because of the specific surface area reduction. However, the $Q_w$ values calculated per 1 m$^2$ increase for Zn$_x$O$_y$/SiO$_2$ andMn$_x$O$_y$/SiO$_2$ in comparison with the unmodified silica, and it remains unchanged for Ni$_x$O$_y$/SiO$_2$. Silica modification with M$_x$O$_y$ significantly changes the pH dependence of zeta potential and affects the surface charge density. A shift of the isoelectric point (pH$_{\rm IEP}$) and a character of the zeta potential $\zeta$ (pH) curve are affected by the M$_x$O$_y$ phase, and pH$_{\rm IEP}$ shifts toward higher values as follows Mn < Zn < Ni.

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