Browsing by Author "Petrova T."

Now showing 1 - 3 of 3
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    Basic holographic characteristics of a panchromatic light sensitive material for reflective autostereoscopic 3D display
    (2009-02-16) Sainov V.; Petrova T.; Ivanov B.; Zdravkov K.; Nazarova D.; Stoykova E.; Minchev G.
    Basic holographic characteristics of a newly developed panchromatic ultrafine grain silver halide light sensitive material for RGB recording of reflective holographic screen for autostereoscopic 3D display are presented. The average grain size is less than 10nm which ensures high resolution, diffraction efficiency, and signal-to-noise ratio (more than 100:1) in a large dynamic range for RGB reflective holographic recording. The decrease of the diffraction efficiency in recording of scattering objects is less than 30 from the maximal values for specular reflection. The analysis of color recording of the reflective holographic screen with one viewing zone is presented on the basis of the so-called sandwich structure built of two layers for multiple holographic recording in blue, green, and red spectral regions.
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    Utilization Perspectives of Lignin Biochar from Industrial Biomass Residue
    (2023-06-01) Naydenova I.; Radoykova T.; Petrova T.; Sandov O.; Valchev I.
    The present study aimed at utilizing technically hydrolyzed lignin (THL), industrial biomass residue, derived in high-temperature diluted sulfuric acid hydrolysis of softwood and hardwood chips to sugars. The THL was carbonized in a horizontal tube furnace at atmospheric pressure, in inert atmosphere and at three different temperatures (500, 600, and 700 °C). Biochar chemical composition was investigated along with its HHV, thermal stability (thermogravimetric analysis), and textural properties. Surface area and pore volume were measured with nitrogen physisorption analysis often named upon Brunauer–Emmett–Teller (BET). Increasing the carbonization temperature reduced volatile organic compounds (40 ÷ 96 wt. %), increased fixed carbon (2.11 to 3.68 times the wt. % of fixed carbon in THL), ash, and C-content. Moreover, H and O were reduced, while N- and S-content were below the detection limit. This suggested biochar application as solid biofuel. The biochar Fourier-transform infrared (FTIR) spectra revealed that the functional groups were gradually lost, thus forming materials having merely polycyclic aromatic structures and high condensation rate. The biochar obtained at 600 and 700 °C proved having properties typical for microporous adsorbents, suitable for selective adsorption purposes. Based on the latest observations, another biochar application was proposed—as a catalyst.
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    Utilization Perspectives of Lignin Biochar from Industrial Biomass Residue
    (2023-06-01) Naydenova I.; Radoykova T.; Petrova T.; Sandov O.; Valchev I.
    The present study aimed at utilizing technically hydrolyzed lignin (THL), industrial biomass residue, derived in high-temperature diluted sulfuric acid hydrolysis of softwood and hardwood chips to sugars. The THL was carbonized in a horizontal tube furnace at atmospheric pressure, in inert atmosphere and at three different temperatures (500, 600, and 700 °C). Biochar chemical composition was investigated along with its HHV, thermal stability (thermogravimetric analysis), and textural properties. Surface area and pore volume were measured with nitrogen physisorption analysis often named upon Brunauer–Emmett–Teller (BET). Increasing the carbonization temperature reduced volatile organic compounds (40 ÷ 96 wt. %), increased fixed carbon (2.11 to 3.68 times the wt. % of fixed carbon in THL), ash, and C-content. Moreover, H and O were reduced, while N- and S-content were below the detection limit. This suggested biochar application as solid biofuel. The biochar Fourier-transform infrared (FTIR) spectra revealed that the functional groups were gradually lost, thus forming materials having merely polycyclic aromatic structures and high condensation rate. The biochar obtained at 600 and 700 °C proved having properties typical for microporous adsorbents, suitable for selective adsorption purposes. Based on the latest observations, another biochar application was proposed—as a catalyst.