364
T. A. Khalyavka et al.
Measurements of UV-vis diffuse reflection spectra (DRUV) of the powders were
carried out at room temperature using a Perkin Elmer Lambda Bio 35 spectrophotometer in the range from 1000 to 200 nm, which allowed converting data of the
corresponding spectra using the Kubelka–Munch equation.
Recording the diffuse reflection spectra in the coordinates F(R) = f (λ, nm),
where F(R) is the Kubelka–Munch function, was carried out with a special rate in
cuvettes with a layer thickness of the investigated powder material of 3 mm and a
reference sample (MgO). All the materials were ground directly in an agate mortar
before recording the DRUV spectra and obtaining constant optical characteristics.
The absolute and relative errors were ±0.01 eV and ±0.3%, respectively.
The values of the specific surface area (S sp ) of the samples as well as pore size
distribution were determined using a Quantachrom Nova Win 2 device. The specific
surface area of the samples was determined based on nitrogen adsorption–desorption
isotherms using the Brunauer–Emmet–Teller (BET) approach. The pore radius (R max )
and the pore volume (V tot ) were calculated from the desorption branches of the
isotherms using the Barret–Joiner–Halenda method [20].
Room temperature FT-IR spectra were recorded with a Perkin Elmer Spectrum
One spectrometer in the spectral region of 4000–400 cm
−1 with spectral resolution
of 4 cm
−1 .
2.3 Photocatalytic Experiments
2.3.1 Photocatalytic Degradation Experiments
Photocatalytic activity of the samples was evaluated for dye Safranine T (C init. =
0.03 g/l) destruction. Before irradiation, catalyst suspension (2 g/l) in aqueous solution was kept in dark up to achieving the adsorption equilibrium. The time of the
sorption equilibrium establishment in the system powder—ST does not exceed 2 h
for all samples. Irradiation of the dye aqueous solutions was performed at room
temperature in a quartz reactor in the presence of air. A standard BUV-30 UV lamp
(30 W, λ = 254 nm, exposure time = 1.5 h) was used for UV irradiation of the dye
aqueous solutions.
Concentrations of the substrate were measured using a Shimadzu UV-2450 spectrophotometer at λ = 520 nm for ST. Discoloration of ST was calculated from the
differences between the initial (100%) and final concentrations of the dye.
For comparative analysis, we conducted an experiment with the well-known and
well-proven P25 photocatalyst (Evonic, S sp ~50 m
2 /g).
T. A. Khalyavka et al.
Measurements of UV-vis diffuse reflection spectra (DRUV) of the powders were
carried out at room temperature using a Perkin Elmer Lambda Bio 35 spectrophotometer in the range from 1000 to 200 nm, which allowed converting data of the
corresponding spectra using the Kubelka–Munch equation.
Recording the diffuse reflection spectra in the coordinates F(R) = f (λ, nm),
where F(R) is the Kubelka–Munch function, was carried out with a special rate in
cuvettes with a layer thickness of the investigated powder material of 3 mm and a
reference sample (MgO). All the materials were ground directly in an agate mortar
before recording the DRUV spectra and obtaining constant optical characteristics.
The absolute and relative errors were ±0.01 eV and ±0.3%, respectively.
The values of the specific surface area (S sp ) of the samples as well as pore size
distribution were determined using a Quantachrom Nova Win 2 device. The specific
surface area of the samples was determined based on nitrogen adsorption–desorption
isotherms using the Brunauer–Emmet–Teller (BET) approach. The pore radius (R max )
and the pore volume (V tot ) were calculated from the desorption branches of the
isotherms using the Barret–Joiner–Halenda method [20].
Room temperature FT-IR spectra were recorded with a Perkin Elmer Spectrum
One spectrometer in the spectral region of 4000–400 cm
−1 with spectral resolution
of 4 cm
−1 .
2.3 Photocatalytic Experiments
2.3.1 Photocatalytic Degradation Experiments
Photocatalytic activity of the samples was evaluated for dye Safranine T (C init. =
0.03 g/l) destruction. Before irradiation, catalyst suspension (2 g/l) in aqueous solution was kept in dark up to achieving the adsorption equilibrium. The time of the
sorption equilibrium establishment in the system powder—ST does not exceed 2 h
for all samples. Irradiation of the dye aqueous solutions was performed at room
temperature in a quartz reactor in the presence of air. A standard BUV-30 UV lamp
(30 W, λ = 254 nm, exposure time = 1.5 h) was used for UV irradiation of the dye
aqueous solutions.
Concentrations of the substrate were measured using a Shimadzu UV-2450 spectrophotometer at λ = 520 nm for ST. Discoloration of ST was calculated from the
differences between the initial (100%) and final concentrations of the dye.
For comparative analysis, we conducted an experiment with the well-known and
well-proven P25 photocatalyst (Evonic, S sp ~50 m
2 /g).