OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt) and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide) depending on solid residue mass fraction m_d = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration m_d has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t) changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t) increases at the increase of m_d; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;m_d) in aqueous solutions of carbamide at λ= 360-760 nm and at m_d = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR) of motor transport exhaust gases.

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