TY - JOUR A1 - Zhang, Yue A1 - Martin, A. A1 - Wolf, G.-U. A1 - Rabe, S. A1 - Worzala, H. A1 - Lücke, B. A1 - Meisel, M. A1 - Witke, Klaus T1 - Structural transformations of VOHPO4.1/2H2O in the Presence of Ammonia JF - Chemistry of materials KW - Vanadium KW - Ammoniak KW - Phosphat KW - Phyrophosphorsäure PY - 1996 SN - 0897-4756 SN - 1520-5002 VL - 8 IS - 5 SP - 1135 EP - 1140 PB - American Chemical Society CY - Washington, DC AN - OPUS4-684 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bandow, Nicole A1 - Finkel, M. A1 - Grathwohl, P. A1 - Kalbe, Ute T1 - Influence of flow rate and particle size on local equilibrium in column percolation tests using crushed masonry JF - Journal of Material Cycles and Waste Management N2 - Column leaching tests are frequently used and accepted for investigation of release of hazardous substances from solid materials. Independent of differences due to the field of application or national regulations, column tests assume that local equilibrium is established in the experiment which facilitates transfer of results to field conditions. In the process of harmonization and standardization within Europe the question on the influence of flow rate and grain size distribution on the local equilibrium was raised. Thus, a set of experiments using two different masonry materials with varying grain size distribution and flow rate were conducted including stop/flow experiments. Results are compared to a numerical model which takes intraparticle pore diffusion-controlled release of Mo and V into the percolating water into account. Due to the relatively high intraparticle porosity of the materials (24–29%) data and model indicate that initially equilibrium-state conditions prevail followed by rapidly decreasing concentrations. The model fits data for Mo and V reasonably well; however, after the initial decline of concentrations (at L/S > 2) extended tailing is observed especially of elements occurring as oxides, which is not captured by the model. KW - Leaching KW - Porosity KW - Stop/flow experiments model KW - Intraparticle diffusion KW - Vanadium KW - Molybdenum PY - 2019 DO - https://doi.org/10.1007/s10163-019-00827-3 SN - 1438-4957 SN - 1611-8227 VL - 21 IS - 3 SP - 642 EP - 651 PB - Springer Japan AN - OPUS4-47265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kowalewska, Z. A1 - Abad Andrade, Carlos Enrique A1 - Okruss, M. A1 - Recknagel, Sebastian T1 - Feasibility of high-resolution continuum source molecular absorption spectrometry for vanadium determination JF - Journal of Analytical Atomic Spectrometry N2 - This work aimed to evaluate high-resolution continuum source molecular absorption spectrometry (HR-CS MAS), traditionally used to determine non-metals, for the determination of a new element, metal, vanadium. VO was selected as a target molecule because it is relatively stable and was expected to be spontaneously generated in a flame or a graphite furnace (GF). The high-resolution overview spectra of the molecule were obtained in a wide range of 480–630 nm, and absorption due to the X4Σ−–C4Σ− electronic transition was registered. A unique instrumental setup, comprising a prototype Modular Simultaneous Echelle Spectrograph (MOSES) and a commercial HR-CS MAS apparatus, was applied in the research. Finally, the spectral area centered at 550.6230 nm was selected for analysis. A method was developed to determine V in solutions of catalysts of heavy petroleum oil hydroprocessing using a commercial HR-CS spectrometer in a flame version. Although sensitivity was relatively poor (characteristic concentration 380 mg L−1), an extremely low noise enabled reaching a satisfactory detection limit (20 mg L−1 in solution, i.e. 0.1% m:m in the catalyst). For the first time vanadium was determined using ordinary air-acetylene flame. The obtained results were consistent with the results of atomic absorption spectrometry with N2O-C2H2 flame. Unfortunately, only a small population of VO molecules could have been generated in GF measurements. Furthermore, the observed VO molecules appeared only at unfavorably high temperatures. The work shows the potential of HR-CS MAS as a scientific tool for investigating the mechanism of processes occurring in the GF. This work can inspire other research of new analytes for HR-CS MAS. KW - Vanadium KW - HR-CS-MAS KW - VO KW - High-resolution continuum source molecular absorption spectrometry KW - AAS PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-569899 DO - https://doi.org/10.1039/D2JA00281G SN - 0267-9477 VL - 38 IS - 2 SP - 472 EP - 483 PB - Royal Society of Chemistry AN - OPUS4-56989 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -