Materials and Equipment

Carbon-metal nanocomposites with titanium as the metal NCMC(Ti) were prepared by the electrochemical method. The process was based on the use of a two-electrode device; one electrode made of a high-density isotropic graphite OEG4 (Russia) (65 mm x 30 mm x 15 mm) and a second electrode was made of titanium plate (65 mm x 30 mm x 1 mm). The electrodes were immersed in a plastic electrolytic cell (120 mm x 140 mm x 105 mm) filled with 0.025 M H2SO4 as the electrolyte. The electrodes had a separation distance of about 10 mm and applied voltage in the range of 5-30 V. The device operation involved two consecutive steps: (1) electrolysis for 2-10 min while the Ti-electrode was as an anode and (2) electrolysis for 2-5 min while the carbon electrode was as an anode. The process was conducted automatically using a twin timer ST-T (Korea).

The size and the shape of nanoparticles were determined by transmission electron microscopy (TEM) (LEO-912-OMEGA, Carl Zeiss, Germany). The size values were averaged over more than 200 nanoparticles from different TEM micrographs of the same sample. Conductivity and pH of the solutions were measured with a WTW bench Multiparameter MultiLab 540. The concentration of Ti in solutions was determined by neutron activation analysis by irradiating water samples in the Nuclear Reactor of the Institute of Nuclear Physics (Tashkent, Uzbekistan). A Ge(Li) detector with a resolution of about 1.9 keV at 1.33 MeV and a 4096-channel analyzer were used for detection of gamma-ray quanta. The area under g-peak of radionuclide 51Ti (half-life T1/2 is 5.8 min, energy of g-peak Eg is 0.319 MeV) was measured to calculate the amount of Ti.

The photocatalytic oxidation of methyl orange (MeO) in a NCMC(Ti) suspension under UV illumination was investigated to evaluate the photocatalytic activity of the nanoparticles. A 150 ml of a 3.2 x 10-3 mol/l MeO solution was filled into a Petri dish. A 60 W UV lamp (DB-60, Russia) fixed at a distance of 25 cm above the solution surface was used as the UV light source and provided radiation power of 1 W/m2 in the interval from 220 nm to 320 nm. The absorbance of the MeO solution was measured with Cary 50 UV-Vis spectrophotometer (Varian) with Xenon flash Lamp.

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