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UV Process Calculations for Food Applications
Published in Tatiana Koutchma, Ultraviolet Light in Food Technology, 2019
Estimation of the quantum yield of HHEVC dye provided an accurate calculation of UV dose. UV dose is defined as the delivered photons from a UV source that reacts with the actinometer resulting in a chemical change at a particular wavelength. Thus, delivered UV dose (Einstein/cm2) or (mJ/cm2) is the ratio of the number of moles of actinometer reacted per cm2 in relation to the quantum yield of the actinometer. The quantum yield of HHEVC dye at 254 nm was calculated based on Equation 23 (Lu, 1981) Q=−dc/dtIo/b(1−10−kbc) where Q is the quantum yield of the HHEVC dye (mol/Einstein); –dc/dt is the change in concentration of the HHEVC dye with time (mol/L.s); Io is the incident UV intensity (mW/cm2); b is the path length (cm); k is the molar absorption coefficient of the dye at 254 nm (L/mol/cm); c is the initial concentration of the dye (mol/L).
Terminology
Published in France Lasnier, Tony Gan Ang, Photovoltaic Engineering Handbook, 2017
Pyrheliometer (Synonymous with the deprecated term actinometer) an instrument using a collimated detector for measuring the direct (beam) radiation received from a solid angle centred on the sun’s disc, on a plane perpendicular to the axis of the solid angle. The output of the instrument can be either irradiance or irradiation. It should have an approximately constant response in the wavelength range 0.3–3.0 μm. Note that most instruments have a field (acceptance) angle of up to 15°. For the purposes of concentrating collectors the field angle should not be greater than 6°.
Available Lamp (or Burner) Technologies
Published in Willy J. Masschelein, Rip G. Rice, Ultraviolet Light in Water and Wastewater Sanitation, 2017
Willy J. Masschelein, Rip G. Rice
Potassium ferri(III) oxalate is transformed into ferro(II) oxalate and the concentration is correlated with the number of photons absorbed. In the region of interest in water treatment, the quantum yield to be considered is 1.23 (see Figure 44). The lowering of the quantum yield at wavelengths under 250 nm makes the ferrioxalate actinometer less adaptable for the evaluation of germicidal efficiency of a lamp compared with the uranyl-oxalic acid method.
Parameters affecting LED photoreactor efficiency in a heterogeneous photo-Fenton process using iron mining residue as catalyst
Published in Journal of Environmental Science and Health, Part A, 2019
Hernán Dario Rojas-Mantilla, Saidy Cristina Ayala-Durán, Raquel Fernandes Pupo Nogueira
The absorbed photon flux (N) in each LED systems was estimated using potassium ferrioxalate as a chemical actinometer[29] (Eq. 1): where N is the photon flux (Einstein s−1), nFe2+ is the number of moles of Fe2+ generated in the solution after irradiation, Ф is the quantum yield (Φ = 1.21 at 365 nm and 0.92 at 460 nm), and t is the irradiation time (s). The reactor was filled with 300 mL of potassium ferrioxalate solution at concentrations of either 6.0 mmol L−1 (for use of the UV LEDs) or 150 mmol L−1 (for use of the visible light LEDs). Aliquots of 5.0 mL were periodically withdrawn (at times of 1, 2, 4, 6, 8, 10, 12, and 14 min) and transferred to 10.0 mL flasks for the determination of Fe2+. The fluxes of absorbed photons (N) were determined to be 8 × 10−8 and 3 × 10−8 Einstein s−1, using the 21 visible light LEDs and the 5 UV LEDs irradiation sources, respectively (Appendix, Fig. A4).
Application of Response Surface Methodology for Coffee Effluent Treatment by Ozone and Combined Ozone/UV
Published in Ozone: Science & Engineering, 2018
Thiago A. Takashina, Vanessa Leifeld, Danielle W. Zelinski, Marcos R. Mafra, Luciana Igarashi-Mafra
The O3/UV process used an artificial source of light supplied by a 125-W Philips mercury vapor lamp and quartz bulb. The intensity of the incident UV-C light irradiation of the lamp was measured with a chemical actinometer based on potassium ferrioxalate (Hatchard and Parker 1956). A radiation intensity of 4.6 10–7 Einstein L−1 s−1 was obtained and a quantum yield ϕ (FeII) = 1.25 was used (Goldstein and Rabani 2008).