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The aim of this experimental study was to evaluate and compare the geochemical impact of pure and impure CO2 on rock forming minerals of possible CO2 storage reservoirs. This geochemical approach takes into account the incomplete purification of industrial captured CO2 and the related effects during injection, and provides relevant data for long-term storage simulations of this specific greenhouse gas. Batch experiments were conducted to investigate the interactions of supercritical CO2, brine and rock-forming mineral concentrates (albite, microcline, kaolinite, biotite, muscovite, calcite, dolomite and anhydrite) using a newly developed experimental setup. After up to 42 day (1000 h) experiments using pure and impure supercritical CO2 the dissolution and solution characteristics were examined by XRD, XRF, SEM and EDS for the solid, and ICP-MS and IC for the fluid reactants, respectively. Experiments with mixtures of supercritical CO2 (99.5 vol.%) and SO2 or NO2 impurities (0.5 vol.%) suggest the formation of H2SO4 and HNO3, reflected in pH values between 1 and 4 for experiments with silicates and anhydrite and between 5 and 6 for experiments with carbonates. These acids should be responsible for the general larger amount of cations dissolved from the mineral phases compared to experiments using pure CO2. For pure CO2 a pH of around 4 was obtained using silicates and anhydrite, and 7-8 for carbonates. Dissolution of carbonates was observed after both pure and impure CO2 experiments. Anhydrite was corroded by approximately 50 wt.% and gypsum precipitated during experiments with supercritical CO2 + NO2. Silicates do not exhibit visible alterations during all experiments but released an increasing amount of cations in the reaction fluid during experiments with impure CO2. Nonetheless, precipitated secondary carbonates could not be identified.
The study reported here evaluates the degree to which metals, salt anions and organic compounds are released from shales by exposure to water, either in its pure form or mixed with additives commonly employed during shale gas exploitation. The experimental conditions used here were not intended to simulate the exploitation process itself, but nevertheless provided important insights into the effects additives have on solute partition behaviour under oxic to sub-oxic redox conditions.
In order to investigate the mobility of major (e.g. Ca, Fe) and trace (e.g. As, Cd, Co, Mo, Pb, U) elements and selected organic compounds, we performed leaching tests with black shale samples from Bornholm, Denmark and Lower Saxony, Germany. Short-term experiments (24 h) were carried out at ambient pressure and temperatures of 100 degrees C using five different lab-made stimulation fluids. Two long-term experiments under elevated pressure and temperature conditions at 100 degrees C/100 bar were performed lasting 6 and 2 months, respectively, using a stimulation fluid containing commercially-available biocide, surfactant, friction reducer and clay stabilizer.
Our results show that the amount of dissolved constituents at the end of the experiment is independent of the pH of the stimulation fluid but highly dependent on the composition of the black shale and the buffering capacity of specific components, namely pyrite and carbonates. Shales containing carbonates buffer the solution at pH 7-8. Sulphide minerals (e.g. pyrite) become oxidized and generate sulphuric acid leading to a pH of 2-3. This low pH is responsible for the overall much larger amount of cations dissolved from shales containing pyrite but little to no carbonate. The amount of elements released into the fluid is also dependent on the residence time, since as much as half of the measured 23 elements show highest concentrations within four days. Afterwards, the concentration of most of the elemental species decreased pointing to secondary precipitations. Generally, in our experiments less than 15% of each analysed element contained in the black shale was mobilised into the fluid. (C) 2015 Elsevier Ltd. All rights reserved.
Portal alumni
(2019)
Derzeit findet weltweit ein Umdenken in der Behindertenpolitik statt. Hat man bislang im Zusammenhang mit behinderten Menschen von der Integration, also der Anpassung behinderter Menschen an die Gesellschaft gesprochen, so geht es inzwischen um Inklusion. Der Begriff bringt zum Ausdruck, dass die Gesellschaft den Bedürfnissen behinderter Menschen im gesellschaftlichen Miteinander gerechter werden will. Angestoßen hat diesen Prozess die Behindertenrechtskonvention der Vereinten Nationen, die aufzeigt, was gegeben sein muss, damit behinderte Menschen ihre Menschenrechte auch wahrnehmen können. In der Konsequenz wird so Inklusion auch zur Kernaufgabe von Hochschulen. Denn diese haben ihre Angebote und Arbeitsbedingungen insgesamt so zu gestalten, dass Menschen mit Behinderungen ohne Diskriminierung an der Hochschularbeit teilhaben können. Wie gut das an der Universität Potsdam gelingt, erzählt die diesjährige Ausgabe unseres Alumni-Magazins. Insbesondere in der Betreuung unserer Studierenden können wir auf ein seit Jahren gut funktionierendes Betreuungsnetzwerk stolz sein, und auch im Hochschulsport gibt es vielzählige inklusive Angebote. Aber natürlich ist da noch viel Luft nach oben. Daher wird die Universität im kommenden Jahr ein Gesamtkonzept „Inklusive Hochschule“ entwickeln, das die erfolgreichen Projekte wie Studierendenförderung, Barrierefreiheit, Gesundheitsförderung, chancengerechte Personalentwicklung oder Antidiskriminierungsarbeit mitdenkt und integriert. Zuvor aber berichten wir in der diesjährigen Ausgabe von Absolventinnen und Absolventen und Studierenden mit Behinderungen oder chronischen Erkrankungen. Wir erfahren, wie inklusiv sie unsere Hochschule erleben oder erlebt haben und vor allem, ob und wie eine gelebte Integration Sichtweise von Menschen verändert (hat). Des Weiteren stellen wir Ehemalige vor, die heute in Schulen, Behörden oder sozialen Einrichtungen beruflich oder ehrenamtlich mit Inklusionsaufgaben befasst sind. Schließlich informieren wir in diesem Heft auch wieder über aktuelle Projekte an der Universität Potsdam.