TY - CONF A1 - Mundra, S. A1 - Furcas, F. E. A1 - Huthwelker, T. A1 - Simon, Sebastian A1 - Borca, C. N. A1 - Provis, J. L. A1 - Gluth, Gregor T1 - Kinetics of Sulfide Oxidation in alkaline solutions studied by X-ray absorption near-edge structure spectroscopy N2 - The oxidation of sulfur in aqueous solutions is an important process in several geochemical and industrial contexts. In concrete technology, it is particularly relevant for the protection of steel reinforcement in slag cement-based concretes, as the presence of sulfides affects the passivation of the steel and corrosion initiation in the presence of chlorides. However, the knowledge about the kinetics of sulfide oxidation in alkaline solutions, such as concrete pore solutions, is incomplete. To address this issue, we prepared solutions with 0.80 M NaOH, and nominally 10, 100 and 350 mM HS−, respectively, and followed the evolution of the sulfur species during bubbling with oxygen-containing gas (concentration 100% or 22%) using X-ray absorption near-edge structure (XANES) spectroscopy at the sulfur K-edge. Polysulfide, thiosulfate, sulfite and sulfate were identified and quantified via linear combination fitting of the spectra, using previously measured standards. A preliminary analysis of the results shows that the initial rate constant of sulfide oxidation depends strongly on the HS− concentration, while it less strongly depending on the oxygen concentration, in line with previous results for lower pH values. Approaches to fit the data to obtain the rate constants of all relevant reactions will be discussed. T2 - 41st Cement & Concrete Science Conference CY - Leeds, Great Britain DA - 12.09.2022 KW - XANES KW - Sulfide oxidation KW - Kinetics PY - 2022 SP - 1 EP - 3 PB - Institute of Materials, Minerals & Mining (IOM3) AN - OPUS4-55650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Brandes, E. A1 - Colson, B. A1 - Frost, K. A1 - Lüth, Peter A1 - Simon, K. A1 - Stolz, T. A1 - Uhlig, S. T1 - Evaluation of the interlaboratory test 2015 – 2016 on the method UN Test L.2 “Sustained combustibility test” / EN ISO 9038:2013 “Determination of sustained combustibility of liquids" N2 - The test methods UN Test L.2 / EN ISO 9038:2013 DIN EN 15188:2007 are applied to characterize the sustained combustibility of liquids i.e. the behaviour of a material under specified test conditions, whereby its vapour can be ignited by an ignition source and sufficient flammable vapour is produced to continue burning for at least 15 s after the source of ignition has been removed. The aims of this interlaboratory test (IT) are the verification and/or the improvement (if necessary) of the verification data (reference material) in Annex B of EN ISO 9038:2013, the assessment of influencing (disturbing) factors (laboratory specific factors, which possibly may have an influence on the test result) and the assessment of the performance of the participating laboratories. It could be demonstrated that the reference materials n-Dodecane, n-Decane and n-Undecane as mentioned in the standard are suitable and the verification shall continue to be valid. Sustained combustibility tests are influenced by several factors like the presence of a draught shield, the experience of the laboratory assistant, verification of the apparatus, calibration of the metering device. Based on the interlaboratory test, the gained experience and the actual results, well-founded measures / actions can be recommended to improve execution of the method. The IT was organized by PTB, BAM and QuoData GmbH in the framework of the co-operation project CEQAT-DGHS Centre for Quality Assurance for Testing of Dangerous Goods and Hazardous Substances. KW - Dangerous goods KW - Hazardous substances KW - Test method KW - Quality assurance KW - Interlaboratory comparison KW - Round robin test KW - Validation KW - Sustained combustibility KW - Reference material KW - Gefahrgut KW - Gefahrstoff KW - Prüfmethode KW - Qualitätssicherung KW - Ringversuch KW - Validierung KW - Selbstunterhaltende Verbrennung KW - Referenzmaterial PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-410270 SN - 978-3-9818270-3-3 SP - 1 EP - 103 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-41027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -