Murad, Enver (1998). "Clays and clay minerals: What can Mössbauer spectroscopy do to help understand them?". Hyperfine Interactions. 117 (1/4): 39–70. doi: 10.1023/A:1012635124874. S2CID 93607974. Boggs, Sam (2006). Principles of sedimentology and stratigraphy (4thed.). Upper Saddle River, N.J.: Pearson Prentice Hall. ISBN 0131547283. C. Mikutta, X-ray absorption spectroscopy study on the effect of hydroxybenzoic acids on the formation and structure of ferrihydrite, Geochim. Cosmochim. Acta, 2011, 75, 5122–5139 CrossRef CAS .

Honestly, these Iron Clays really have opened my eyes. Previously resistant to investing in accessories, I am now actually looking for games with the worst cardboard counters just so that I can revel in superior counter smugness! If you are fed up with cardboard coins lowering your fun level, I highly recommend investing in Iron Clays. After all, stunning counters are for life, not just for Christmas! See also: Pottery Hexagonal sheets of the clay mineral kaolinite ( SEM image, 1,340× magnification) L. T. Kuhn, K. Lefmann, C. R. H. Bahl, S. N. Ancona, P. A. Lindgard, C. Frandsen, D. E. Madsen and S. Morup, Neutron study of magnetic excitations in 8-nm alpha-Fe 2O 3 nanoparticles, Phys. Rev. B: Condens. Matter Mater. Phys., 2006, 74, 184406 CrossRef . Previous studies have also investigated the sorption of Fe 2+ to different clay minerals at various Fe-loadings. 14,30 Collectively, the literature results suggested that depending on the Fe-loading, various Fe( II)- and Fe( III)-containing solids formed. At high Fe-loadings (0.53–2 mol Fe per kg) the formed secondary phases were predominantly Fe( II)-containing phases. 19,21 At low Fe-loadings (0.002–0.08 mol Fe per kg) mainly Fe( III)-containing phases were observed. 30,67 Our current study are in agreement with these results. The formation of an LDH phase with Fe in the octahedral sheet was observed for high Fe-loading anoxic sorption samples as shown by Jones et al. 19 Contrary, in the study by Zhu et al. 21 no Fe 2+ oxidation was observed during sorption of Fe 2+ onto Syn-1 and the formation of FeAl-LDH was suggested as the main solid phase forming. However, sorption experiments in the study by Zhu et al. were performed in an atmosphere with 5% H 2 and 95% N 2. Such elevated H 2 concentration are expected to disable H + to oxidize Fe 2+ ( cf. Fig. S2 †) and to suppress the formation of green rust as the main secondary phase. In our low Fe-loading samples, over half of Fe( II) was oxidized to Fe( III), from which a large fraction was incorporated into newly formed clay minerals. This result shows that clay minerals can play an important role in the mobility of Fe 2+ under anoxic conditions. Effects of aeration of anoxic sorption samples on Fe speciation To understand the effects of O 2-exposure on the speciation of Fe in clay suspensions (Syn-1) that were anoxically equilibrated for 1 or 30 days with Fe 2+, the anoxic suspensions were exposed to ambient air for 24 hours. Aeration resulted in a further increase in percent Fe sorption (see Fig. 4a, b and Table S2 †), despite a drop in suspension pH (between 0.8 and 3.1 pH values) as a result of hydrolysis of Fe 3+ (Table S3 †). Due to the high O 2 sensitivity of Fe 2+ at near-neutral pH, rapid oxidation of adsorbed and dissolved Fe 2+, hydrolysis of Fe 3+, and precipitation of Fe( III)-(oxyhydr)oxides may occur. This results in the release of protons, explaining the observed decrease of suspension pH.Fig. 1 Percentage of Fe 2+ sorbed on Syn-1 (∼1 g L −1) as a function of pH at different CaCl 2 concentrations. Samples in DDI water had a Ca 2+ concentration of ∼0.1 mM after 1 day equilibration. Total Fe 2+ concentrations of (a) 0.05 and (b) 0.5 mM were added and equilibrated for 1 day with 1 g L −1 Syn-1. If a game has great components, it can elevate the experience to something next-level. Sometimes it can even save one that has a few bumps in its design. Not often. But sometimes. On the other hand, if a game has poor components, then that’s a real knife-edge moment. Keep it despite the bargain-basement bits? Or lose it and seek something similar but better furnished? Iron Investment J. B. Dixon, S. B. Weed and R. C. Dinauer, Minerals in soil environments, Soil Science Society of America, Madison, Wis., USA, 2nd edn, 1989 Search PubMed .

In the XAS samples, the sorbed fraction of Fe 2+ was higher at pH ∼8 than at pH ∼7 (Table S2 †). The amount of sorbed Fe 2+ also slightly increased with increasing equilibration time from day 1 to 30 (Table S2 and Fig. S3 †), e.g., by 0.02 mol Fe per kg clay at pH 7. This observation is consistent with findings by Zhu et al., 34 who observed an increase in Fe 2+ sorption to Syn-1 during 5 days at pH 7.5. Such increases of Fe 2+ sorption suggest that slow sorption processes were taking place. Possible mechanisms explaining slow sorption kinetics include dissolution and precipitation reactions on surfaces. 35–44 with smectites: Temporal changes in redox reactivity and the formation of green rust, Environ. Sci. Technol., 2017, 51, 12573–12582 CrossRef CAS PubMed . A. M. Scheidegger, G. M. Lamble and D. L. Sparks, Spectroscopic evidence for the formation of mixed-cation hydroxide phases upon metal sorption on clays and aluminum oxides, J. Colloid Interface Sci., 1997, 186, 118–128 CrossRef CAS PubMed .

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A. Manceau and M. L. Schlegel, Texture effect on polarized EXAFS amplitude, Phys. Chem. Miner., 2001, 28, 52–56 CrossRef CAS . The FT of the EXAFS spectra of the low Fe-loading anoxic samples equilibrated at pH ∼8, showed a second peak at ∼2.75 Å (uncorrected for phase shift). This second shell was fitted with Fe located at a radial distance of 3.15–3.17 Å and a coordination number of 1.8–2.1. The fitted distance for the second shell corresponds with an intermediate distance of edge-sharing Fe atoms around Fe( II) and Fe( III) as in fougerite 56 and lepidocrocite, 64 respectively. This is consistent with the results obtained by LCF and Mössbauer spectroscopy. Rivkin AS, Volquardsen EL, Clark BE (2006). "The surface composition of Ceres: Discovery of carbonates and iron-rich clays" (PDF). Icarus. 185 (2): 563–567. doi: 10.1016/j.icarus.2006.08.022. Chrzanowski, Wojciech; Kim, Sally Yunsun; Abou Neel, Ensanya Ali (2013). "Biomedical Applications of Clay". Australian Journal of Chemistry. 66 (11): 1315. doi: 10.1071/CH13361. To investigate the sorption mechanism of Fe 2+ to Syn-1 by XAS further, an additional set of samples was prepared at pH 7 or 8 under anoxic conditions containing 5 g L −1 clay, 0.25 or 2.5 mM Fe 2+, and 50 mM CaCl 2. The high CaCl 2 concentration and pH values were selected to focus on sorption processes on edge surfaces, which are expected to dominate under these conditions. Furthermore, at pH < 8 the dissolved Fe 2+ concentrations in the suspensions were always below saturation with respect to Fe(OH) 2 (Table S1 †).