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In comparison to the adsorption of hydrocarbons, the adsorption of mercury on activated carbons reveals many unexpected results. Both physisorptive and chemisorptive mechanisms play a role even in the adsorption on nonimpregnated activated carbons. In this work, the adsorption of Hg0 from a N2 carrier gas stream is studied on three commercial adsorbents. Single and cumulative breakthrough curves are measured in a fixed bed at temperatures of 25–100 °C and mercury concentrations of 50–1000 μg m–3. Isosteric heats of adsorption are calculated from the measured adsorption isotherms. Here, adsorption enthalpies in the range of 50% of the vaporization enthalpy are determined. In addition, desorption experiments are conducted to distinguish the contributions of physisorption and chemisorption. A dynamic simulation of experimental breakthrough curves yields diffusion coefficients, which are discussed with respect to the concentration and temperature dependence of diffusion mechanisms in mercury physisorption.

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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.