UV spectroscopic properties of principal inorganic ionic species in natural waters

Abstract

The UV spectroscopic properties of the principal inorganic ionic species in natural waters were investigated at 25 °C in the wavelength range 195 to 280 nm. All absorbing species were identified and the corresponding molar absorptivities were determined experimentally. No cations were found to influence the UV spectrum. Relatively high molar absorptivities were observed for iodide, bromide and nitrate. The UV spectra of natural waters were calculated using the molar absorptivities and compared with observed signals from synthetic samples. This enabled the dominant components to be determined. Both bromide and nitrate have significant influence on the UV spectrum of natural waters. The study results can be used to predict the UV spectra of ionic solutions and thus evaluate the suitability of UV spectroscopy for given measurement projects.

Development of a Measuring Method for the Determination of Bisulfite and Sulfite in Seawater

“…In order to determine the interaction influences of the seawater components on the extinction coefficients of bisulfite and sulfite, solutions of the sulfur species together with individual background electrolytes were examined in the first step. The procedure of the measurements to determine the extinction coefficients of ions is described by Birkmann .…”

“…All salts used in the procedure have reagent grade with a purity of at least 99 % (Sigma Aldrich). A detailed description of the experimental setup, procedure, and the introduction of the measurement limit can be found in Birkmann .…”

“…As with the measurements with only one background electrolyte, a measurable reduction in the absorption strength of both components can be observed. Based on a characterization of the absorption behavior of seawater [13] it could be shown that the ions nitrate and bromide absorb significantly in the wavelength range 200 to 245 nm. For the extinction of the seawater, this leads to an exceeding of the instrumental measurement limit of E = 3 at wavelengths below 213 nm, so that the spectral range of shorter wavelengths can no longer be analyzed.…”

“…Within the framework of a parameter study, the number of independent variables used for modeling was systematically varied with the aim of minimizing the prediction error. Based on the spectroscopic investigations of seawater from Birkmann et al , the influence of the components in seawater on the detection of sulfur is described and an artificial seawater is proposed in which all relevant interactions and interferences occur. A practical PLS model was developed for this complex system.…”

Recovery and concentration of ammonia from return liquor to promote enhanced CO2 absorption and simultaneous ammonium bicarbonate crystallisation during biogas upgrading in a hollow fibre membrane contactor

“…Bicarbonate concentration was measured using UV absorption at 215nm (Wilson et al, 2001;Mookherji et al, 1966;Birkmann et al, 2018) (Jenway 6715, Cole-Parmer, Stone, UK).…”