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Laboratory courses are key to science, technology, engineering, and mathematics (STEM) programs in higher education, but often lack the flexibility for distance learning and inclusiveness for all students. To address these challenges, TU Bergakademie Freiberg introduced remote laboratories not only for international degree programs and the "Disti4Study" application, which provides interactive visualization of industrial thermal separation processes. This paper focuses on the development and didactic challenges associated with the "Continuous Distillation Laboratory". It illustrates how rethinking the technical and didactic frameworks of traditional laboratories can align with new learning objectives, such as those related to Industry 4.0, including the Internet of Things and data management. [ABSTRACT FROM AUTHOR]

Quantification understanding, and prediction of physical rock properties rely so far predominantly on laboratory analyses of cores and plugs. Based on such data, petrophysical models are found that relate both microstructural properties and environmental conditions to geophysically accessible quantities. When considering reactive rock–fluid–gas systems, for example in geothermal energy, enhanced oil recovery or carbon dioxide sequestration, especially with carbonatic rock matrix, this approach is costly and time-consuming at best, or impossible to implement at worst. This is based on the two following reasons: First, porosity, permeability and accessible internal surface area in solid rock plugs are often so low that experimental time duration of many months or even years would be required to achieve chemical equilibrium. Secondly, plugs are single specimens of their — generally heterogeneous — original rock formation, which strongly questions the representativeness of single-plug data. To overcome these shortcomings, we present a new methodology based on the combination of systematic crushing, multimethod laboratory measurements and model-based computational evaluation with solving an inverse problem. As a first step, a large amount of undisturbed rock is intentionally crushed and divided in several particle size classes. Then, petrophysical laboratory measurements are carried out on all particle size classes. The resulting data set is finally inverted for the intended properties of the undisturbed rock. This inverse problem entails a three-level forward model, which parametrizes the undisturbed rock properties, particle characteristics and particle packings, but can also be freely adapted to other tasks by any suitable model representation. The three-level model is designed to enforce the petrophysical correlation of all properties at all levels while using a minimal set of model parameters, thus keeping the inverse problem overdetermined. For the inversion, we have developed a publicly available software tool (AnyPetro) based on a Gauss–Newton inversion scheme to minimize a damped least-squares objective function. To demonstrate and validate the proposed methodology, we present a study using five rock types — four carbonates and one sandstone as a reference. Laboratory measurements of complex electrical conductivity (from spectral induced polarization), specific surface (from nitrogen adsorption) and intraparticle porosity (from mercury intrusion) have been carried out on eight particle size classes and on plugs of each rock for comparison. Supportive and complementary analyses include, for example particle geometry, nuclear magnetic resonance, scanning electron microscopy, computer tomography, uniaxial compression strength and mineralogical composition. We show that our new methodology is highly capable of robustly recovering the complex electrical conductivity, specific surface and porosity of the undisturbed rocks from the measured data. The resulting sets of model parameters are petrophysically reasonable and verifiable. The presented methodology can further be applied to the use of drill cuttings as sample material, which is often the only available rock material from deep wells. Our findings also represent a methodological advance for laboratory experiments on reactive systems and both the interpretation and prediction of petrophysical rock properties in such systems. [ABSTRACT FROM AUTHOR]

For the material use of the arising huge amounts of agricultural by-products (e.g., rice/wheat straw), a concept for the production of formed carbon adsorbent materials is presented hereinafter - the main process step is a wet pelleting process. Due to an additional activation step of the biomasses or the carbons, respectively, the adsorption properties can be improved. The presented study shows results for the production of formed carbons and the activation of not-pelleted biomasses or carbons, respectively, as a first step before a later combination of both process steps. [ABSTRACT FROM AUTHOR]

The spectral complex conductivity of a water-bearing sand during interaction with carbon dioxide (CO2) is influenced by multiple, simultaneous processes. These processes include partial saturation due to the replacement of conductive pore water with CO2 and chemical interaction of the reactive CO2 with the bulk fluid and the grain-water interface. We present a laboratory study on the spectral induced polarization of water-bearing sands during exposure to and flow-through by CO2. Conductivity spectra were measured successfully at pressures up to 30 MPa and 80 °C during active flow and at steady-state conditions concentrating on the frequency range between 0.0014 and 100 Hz. The frequency range between 0.1 and 100 Hz turned out to be most indicative for potential monitoring applications. The presented data show that the impact of CO2 on the electrolytic conductivity may be covered by a model for porewater conductivity, which depends on salinity, pressure and temperature and has been derived from earlier investigations of the pore-water phase. The new data covering the three-phase system CO2-brine-sand further show that chemical interaction causes a reduction of surface conductivity by almost 20 per cent, which could be related to the low pH-value in the acidic environment due to CO2 dissolution and the dissociation of carbonic acid. The quantification of the total CO2 effect may be used as a correction during monitoring of a sequestration in terms of saturation. We show that this leads to a correct reconstruction of fluid saturation from electrical measurements. In addition, an indicator for changes of the inner surface area, which is related to mineral dissolution or precipitation processes, can be computed from the imaginary part of conductivity. The low frequency range between 0.0014 and 0.1 Hz shows additional characteristics, which deviate from the behaviour at higher frequencies. A Debye decomposition approach is applied to isolate the feature dominating the data at lowfrequencies. We conclude from our study that electrical conductivity is not only a highly sensitive indicator for CO2 saturation in pore space. When it is measured in its full spectral and complex form it contains additional information on the chemical state of the system, which holds the potential of getting access to both saturation and interface properties with one monitoring method. [ABSTRACT FROM AUTHOR]

The electrical rock conductivity is a sensitive indicator for carbon dioxide (CO2) injection and migration processes. For a reliable balancing of the free CO2 in pore space with petrophysical models such as Archie's law or for the detection of migrating CO2, detailed knowledge of the pore water conductivity during interaction with CO2 is essential but not available yet. Contrary to common assumptions, pore water conductivity cannot be assumed constant since CO2 is a reactive gas that dissolves into the pore water in large amounts and provides additional charge carriers due to the dissociation of carbonic acid. We consequently carried out systematic laboratory experiments to quantify and analyse the changes in saline pore water conductivity caused by CO2 at thermodynamic equilibrium. Electrical conductivity is measured on pore water samples for pressures up to 30 MPa and temperatures up to 80 °C. The parameter range covers the gaseous, liquid and supercritical state of the CO2 involved. Pore water salinities from 0.006 up to 57.27 g L-1 sodium chloride were investigated as well as selective other ion species. At the same time, the CO2 concentration in the salt solution was determined by a wet-chemical procedure. A two-regime behaviour appears: for small salinities, we observe an increase of up to more than factor 3 in the electrical pore water conductivity, which strongly depends on the solution salinity (low-salinity regime). This is an expected behaviour, since the additional ions originating from the dissociation of carbonic acid positively contribute to the solution conductivity. However, when increasing salinities are considered this effect is completely diminished. For highly saline solutions, the increased mutual impeding causes the mobility of all ions to decrease, which may result in a significant reduction of conductivity by up to 15 per cent despite the added CO2 (high-salinity regime). We present the data set covering the pressure, temperature, salinity and ion species dependence of the CO2 effect. Furthermore, the observations are analysed and predicted with a semi-analytical formulation for the electrical pore water conductivity taking into account the species' interactions. For the applicability of our results in practice of exploration and monitoring, we additionally provide a purely empirical formulation to compute the impact of CO2 on pore water conductivity at equilibrium which only requires the input of pressure, temperature and salinity information. [ABSTRACT FROM AUTHOR]

Collagen is increasingly used as material for medical devices because of its excellent biocompatibility. To achieve long-term durability, the collagen materials are dried and subsequently sterilized. Most common sterilization methods are unsuitable as they cause denaturation. Currently, only ethylenoxide or γ irradiation preserves the microscopic and macroscopic collagen structure. However, both methods require high safety standards and include the risk of uncontrolled crosslinking or cleavage of protein chains. Here, supercritical carbon dioxide is used for the sterilization of different collagen devices. Thereby, the influence of pressure, temperature, sterilization aid and dosage, and different operation modes is determined. The method is a promising alternative to existing sterilization techniques. [ABSTRACT FROM AUTHOR]

Collagen is increasingly used as material for medical devices because of its excellent biocompatibility. To achieve long-term durability, the collagen materials are dried and subsequently sterilized. Most common sterilization methods are unsuitable as they cause denaturation. Currently, only ethylenoxide or γ irradiation preserves the microscopic and macroscopic collagen structure. However, both methods require high safety standards and include the risk of uncontrolled crosslinking or cleavage of protein chains. Here, supercritical carbon dioxide is used for the sterilization of different collagen devices. Thereby, the influence of pressure, temperature, sterilization aid and dosage, and different operation modes is determined. The method is a promising alternative to existing sterilization techniques. [ABSTRACT FROM AUTHOR]

Industrial extraction of montan wax from lignite requires a specific pre-treatment of raw material concerning milling and drying aiming on particles with sufficient strength and grain size distribution. The wax or its intermediate is a basic material, for example, in foundry, asphalt, or cosmetic industry. First time, the effects of drying temperature and moisture content of lignite samples on extraction rate, extraction yield, and mechanical properties were investigated. The examination was conducted out in lab-scale with two different mechanical pre-treatments. The experimental conditions ranged from 85 to 135°C concerning drying temperature and 1-20% for moisture content. The kinetic analysis of analytical wax extraction was made by adopting an approach from natural material extraction by Bucić-Kojić et al. . The extraction yield as well as the extraction rate is increasing with increasing moisture content until a constant level is reached whereas temperature of drying air showed unexpectedly no significant influence on both parameters. The mechanical properties of the solids were determined by a pressure stress test. For both investigated solids, mechanical strength increases with lowering moisture content. The solids produced with the novel pre-treatment showed in general a favorable compression behavior than the normally used particles. Practical applications: Industrial montan wax extraction process requires hard lignite particles, which do not decay during processing and handling. The strength of lignite is highly influenced by moisture content besides other factors such as the kind of lignite, the surface mine, drying technology, milling, and processing. The strength of lignite particles increases until a maximum in solidity is reached while drying down from deposit moisture of about 50 wt%. Lignite beds with high moisture content or wide grain size distribution offer the risk of their compression. Such compressed beds are not suitable for extraction due to a lowering or even total loss of permeability for the solvent. The selection of an adequate drying procedure and moisture content of the lignite avoids such problems. But a decrease of moisture content to 1% is known to reduce extraction yield considerably, e.g., the maximal extraction yield requires a specific moisture content of lignite particles . [ABSTRACT FROM AUTHOR]

ABSTRACT We conducted a detailed experimental investigation of the effect of CO2 injection on the electrical conductivity of water bearing porous media, needed for an improved geophysical monitoring of CO2 storage reservoirs. Therefore, we developed an experimental set-up that allows to investigate electrical characteristics of the injection process as well as the impact of dissolved CO2 on pore water conductivity. We found that a gaseous, fluid and supercritical pure CO2 phase bears no relevant conductivity at pressures up to 13 MPa and temperatures up to 50° C. When CO2 dissolves in pore water, pressure-dependent dissociation processes can double the pore water conductivity, that can be used in leakage detection. This is quantified by an adaptation of Archie's law. The empirical adaptation and the experimental data are confirmed by combined geochemical-geoelectrical modelling. Furthermore, water-saturated sand samples were investigated while CO2 displaced the pore water at pressures up to 13 MPa and temperatures up to 40° C. A decrease in electrical conductivity by a factor of up to 33 was measured, corresponding to a residual water saturation of 14-19%. Qualitatively, a decrease was also demonstrated under supercritical conditions. As an integrative interpretation, a conceptual model of electrical rock properties during CO2 sequestration is presented. [ABSTRACT FROM AUTHOR]