Effect of FSP-inserted Cu on Physicochemical Properties of Cu/Al2O3 Catalyst

The copper inserted on Cu/Al2O3 catalysts with various Cu loading (10-40 wt%) were synthesized via flame spray pyrolysis (FSP). These catalysts were characterized using X-ray diffraction (XRD), N2 physisorption, temperature programmed reduction (TPR) and X-ray absorption near edge spectroscopy (XANES). The XRD results confirmed the formation of copper aluminate spinel (CuAl2O4) on the FSP-inserted Cu catalyst. The CuO crystallite size of the Cu/Al2O3 catalysts was increased with increasing Cu loading during the flame spray pyrolysis step. The incorporation of copper and aluminum precursors during the flame spray pyrolysis step can inhibit the growth of Al2O3 particles resulting in higher BET surface area and smaller particle size than pure Al2O3 support. The data from TPR and XANES results can predict the ratio of CuO and CuAl2O4 in the FSP-made support. Less than 20 wt% loading of the FSP-inserted Cu showed high concentration of CuAl2O4 phase in the FSP-made material. The composition of CuO and CuAl2O4 phase can be controlled by varying Cu loading in flame spray pyrolysis step. This is a promising alternative way to synthesize the desired catalyst. An example was the catalytic testing of the selective hydrogenolysis of glycerol. The presence of both CuO and CuAl2O4 phases in the Cu/Al2O3 catalyst enhanced the catalytic activity and promoted the selectivity to acetol product. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Phosphorus speciation in long-term drained and rewetted peatlands of northern germany

Previous studies, conducted at the inception of rewetting degraded peatlands, reported that rewetting increased phosphorus (P) mobilization but long-term effects of rewetting on the soil P status are unknown. The objectives of this study were to (i) characterize P in the surface and subsurface horizons of long-term drained and rewetted percolation mires, forest, and coastal peatlands and (ii) examine the influence of drainage and rewetting on P speciation and distributions using wet-chemical and advanced spectroscopic analyses. The total P was significantly (p < 0.05) different at the surface horizons. The total concentration of P ranged from 1022 to 2320 mg kg−1 in the surface horizons and decreased by a factor of two to five to the deepest horizons. Results of the chemical, solution 31P nuclear magnetic resonance (NMR), and P K-edge X-ray absorption near-edge structure (XANES) indicated that the major proportions of total P were organic P (Po). In the same peatland types, the relative proportions of Po and stable P fractions were lower in the drained than in the rewetted peatland. The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

The Adsorption of Per- and Polyfluoroalkyl Substances (PFASs) onto Ferrihydrite Is Governed by Surface Charge

An improved quantitative and qualitative understanding of the interaction of per- and polyfluoroalkyl substances (PFASs) and short-range ordered Fe (hydr)oxides is crucial for environmental risk assessment in environments low in natural organic matter. Here, we present data on the pH-dependent sorption behavior of 12 PFASs onto ferrihydrite. The nature of the binding mechanisms was investigated by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and by phosphate competition experiments. Sulfur K-edge XANES spectroscopy showed that the sulfur atom of the head group of the sulfonated PFASs retained an oxidation state of +V after adsorption. Furthermore, the XANES spectra did not indicate any involvement of inner-sphere surface complexes in the sorption process. Adsorption was inversely related to pH (p &lt; 0.05) for all PFASs (i.e., C-3-C-5 and C-7-C-9 perfluorocarboxylates, C-4, C-6, and C-8 perfluorosulfonates, perfluorooctane sulfonamide, and 6:2 and 8:2 fluorotelomer sulfonates). This was attributed to the pH-dependent charge of the ferrihydrite surface, as reflected in the decrease of surface zeta-potential with increasing pH. The importance of surface charge for PFAS adsorption was further corroborated by the observation that the adsorption of PFASs decreased upon phosphate adsorption in a way that was consistent with the decrease in ferrihydrite zeta-potential. The results show that ferrihydrite can be an important sorbent for PFASs with six or more perfluorinated carbons in acid environments (pH &lt;= 5), particularly when phosphate and other competitors are present in relatively low concentrations

Oxidation state analysis of LiFeSixP1-xO4/C (x = 0.06) with X-ray absorption near edge structure (XANES) in Fe K-edge and Si K-edge

The development of LiFePO4 as a cathode materials on lithium-ion battery was increased with the use of additional techniques such as atomic doping and coating. The material used in this report was LiFeSi0.06P0.94O4/C (LFP Si-6%), synthesized with doping silicon 6% and 11wt% carbon coating by a solid state method. X-ray Absorption Spectroscopy (XAS) characterization was used to investigate the effect on electronic and atomic structure of LFP Si-6%, especially in X-ray Absorption Near Edge Strucuture (XANES) region. XANES data measured on Fe K-edge and Si K-edge. Fe foil, FeO, Fe2O3, FePO4, Si powder, SiO, SiO2 were used as a standard sample for comparison with the result of LFP Si-6%. XANES analysis showed that the energy absorption of Fe K-edge and Si K-edge in LFP Si-6% was 7124.94 eV and 1846.16 eV, respectively. The oxidation state of Fe was Fe2.576+ between Fe2+ and Fe3+, while Si was close to the estimation of Si4+. In addition, the linear combination fitting (LCF) in XANES Fe K-edge was performed to show the ratio of Fe2+/Fe3+ (FeO/Fe2O3)

Synthesis and structural characterisation of solid titanium(IV) phosphate materials by means of X-ray absorption and NMR spectroscopy

Solid titanium phosphate, TiP, materials hold great promise for wastewater treatment for removal of metal ions and complexes. A series of TiP materials, synthesised at mild conditions and short reaction times, have been structurally characterised using solid-state X-ray absorption spectroscopy, phosphorus and titanium K edge XANES and EXAFS, and P-31 and Ti-47/49 NMR spectroscopy. The titanium K edge EXAFS data of alpha-Ti(HPO4)(2)center dot H2O (alpha-TiP) revealed octahedral coordination of oxygens around titanium. Repeated washing of primary beta-/gamma-TiP with hydrochloric acid results in formation of a weakly ordered solid, TiO(OH)(H2PO4)center dot H2O, TiP1-H. The structure of TiP1-H is shown by Ti EXAFS to be a titanyl compound, containing a short Ti=O bond. The analogous data for linked titanium phosphate compounds (LTP) disclosed that inter-linkage occurs between alpha-TiP and titanyl phosphate units, supported by P-31-P-31 NOESY NMR data. Ti-47/49 NMR and Ti pre-edge XANES show evidence of two different titanium environments in LTP, one very similar to that observed in TiP1-H and a second more symmetric octahedral environment. Data are discussed in terms of induced acidic hydrolyses of titanium(IV) and phosphate counterpart during washings with hydrochloric acid and water. A straightforward relation between synthesis parameters/post synthetic treatment and structural re-arrangement in the materials is established

Evolution of phosphorus speciation with depth in an agricultural soil profile

With time, different soil-forming processes such as weathering, plant growth, accumulation of organic matter, and cultivation are likely to affect phosphorus (P) speciation. In this study, the depth distribution of P species was investigated for an agricultural clay soil, Lanna, Sweden. Small amounts of apatite-P was demonstrated in the topsoil whereas the speciation of Pat 70-100 cm depth consisted of approximately 86% apatite according to P K-edge XANES (X-ray absorption near-edge structure) spectroscopy. Because there were only minor differences in bulk mineralogy and texture, these variations in P speciation were interpreted as the result of apatite weathering of the topsoil. Speciation modeling on soil extracts supported this idea: hydroxyapatite was not thermodynamically stable in the top 50 cm of the soil. Apatite was enriched in the bulk soil relative to the clay fraction, as expected during apatite dissolution. Combined results from batch experiments, XANES spectroscopy and X-ray diffraction suggested chemical transformations of the topsoil as a result from accumulation of organic matter and airing from tillage followed by enhanced weathering of apatite, amphiboles, clay minerals, and iron oxides. This caused the formation of poorly crystalline secondary iron and aluminum (hydr)oxides in the topsoil, which retained part of the released P from apatite. Other P was incorporated into organic forms. Furthermore, the results also showed that short-term acidification below the current pH value (below 5.5 in the topsoil and 7.2 in the deeper subsoil) caused significant solubilization of P. This is attributed to two different mechanisms: the instability of Al-containing sorbents (e.g. Al hydroxides) at low pH (in the topsoil), and the acid-mediated dissolution of apatite (the subsoil). (C) 2016 Elsevier B.V. All rights reserved

Synthesis and structural characterisation of solid titanium(iv) phosphate materials by means of X-ray absorption and NMR spectroscopy

Solid titanium phosphate, TiP, materials hold great promise for wastewater treatment for removal of metal ions and complexes. A series of TiP materials, synthesised at mild conditions and short reaction times, have been structurally characterised using solid-state X-ray absorption spectroscopy, phosphorus and titanium K edge XANES and EXAFS, and 31P and 47/49Ti NMR spectroscopy. The titanium K edge EXAFS data of α-Ti(HPO4)2·H2O (α-TiP) revealed octahedral coordination of oxygens around titanium. Repeated washing of primary β-/γ-TiP with hydrochloric acid results in formation of a weakly ordered solid, TiO(OH)(H2PO4)·H2O, TiP1-H. The structure of TiP1-H is shown by Ti EXAFS to be a titanyl compound, containing a short Ti[double bond, length as m-dash]O bond. The analogous data for linked titanium phosphate compounds (LTP) disclosed that inter-linkage occurs between α-TiP and titanyl phosphate units, supported by 31P–31P NOESY NMR data. 47/49Ti NMR and Ti pre-edge XANES show evidence of two different titanium environments in LTP, one very similar to that observed in TiP1-H and a second more symmetric octahedral environment. Data are discussed in terms of induced acidic hydrolyses of titanium(IV) and phosphate counterpart during washings with hydrochloric acid and water. A straightforward relation between synthesis parameters/post synthetic treatment and structural re-arrangement in the materials is established

Phosphorus speciation in the organic layer of two Swedish forest soils 13-24 years after wood ash and nitrogen application

Application of wood ash to forests can restore pools of phosphorus (P) and other nutrients, which are removed following whole tree harvesting. Yet, the mechanisms that affect the fate of ash-P in the organic layer are less well known. Previous research into the extent to which ash application leads to increased P solubility in the soil is contradictory. We combined synchrotron P K-edge XANES spectroscopy, mu-XRF microscopy, and chemical ex-tractions to examine the speciation and solubility of P. We studied organic horizons of two long-term field ex-periments, Riddarhyttan (central Sweden), which had received 3, 6, and 9 Mg ash ha -1, and Ro center dot dalund (northern Sweden), where 3 Mg ash ha- 1 had been applied alone or combined with N every-three years since 2003. At the latter site, we also determined P in aboveground tree biomass. Overall, the ash application increased P in the organic layer by between 6 and 28 kg P ha -1, equivalent to 17-39 % of the initial P content in the applied ash. At Ro center dot dalund, there was 4.6 kg Ca-bound P ha- 1 (9.5 %) in the ash treatment compared to 1.6 kg ha- 1 in the ash + N treatment and < 0.4 kg ha- 1 in the N treatment and the control. At Riddarhyttan, only the treatment with the highest ash dose had residual Ca-bound P (3.8 kg ha -1). In contrast, the ash application increased Al-bound P (p < 0.001) with up to 15.6 kg P ha -1. Moreover, the ash increased Olsen-P by up to two times. There was a strong relationship between the concentrations of Olsen-P and Al-bound P (R2 = 0.83, p < 0.001) as well as Fe-bound P (R2 = 0.74, p = 0.003), suggesting that the ash application resulted in an increased amount of relatively soluble P associated with hydroxy-Al and hydroxy-Fe compounds. Further, there was an 18 % increase in P uptake by trees in the ash treatment. By contrast, repeated N fertilization, with or without ash, reduced Olsen-P. The lower P extractability was concomitant with a 39 % increase in plant P uptake in the N treatment, which indicates elevated P uptake in response to higher N availability. Hence, the application of wood ash increased Al-bound P, easily available P, and P uptake. N fertilization, while also increasing tree P uptake, instead decreased easily available P and did not cause a shift in soil P speciation

Phosphorus speciation in the organic layer of two Swedish forest soils 13–24 years after wood ash and nitrogen application

Application of wood ash to forests can restore pools of phosphorus (P) and other nutrients, which are removed following whole tree harvesting. Yet, the mechanisms that affect the fate of ash-P in the organic layer are less well known. Previous research into the extent to which ash application leads to increased P solubility in the soil is contradictory. We combined synchrotron P K-edge XANES spectroscopy, µ-XRF microscopy, and chemical extractions to examine the speciation and solubility of P. We studied organic horizons of two long-term field experiments, Riddarhyttan (central Sweden), which had received 3, 6, and 9 Mg ash ha−1, and Rödålund (northern Sweden), where 3 Mg ash ha−1 had been applied alone or combined with N every-three years since 2003. At the latter site, we also determined P in aboveground tree biomass. Overall, the ash application increased P in the organic layer by between 6 and 28 kg P ha−1, equivalent to 17–39 % of the initial P content in the applied ash. At Rödålund, there was 4.6 kg Ca-bound P ha−1 (9.5 %) in the ash treatment compared to 1.6 kg ha−1 in the ash + N treatment and < 0.4 kg ha−1 in the N treatment and the control. At Riddarhyttan, only the treatment with the highest ash dose had residual Ca-bound P (3.8 kg ha−1). In contrast, the ash application increased Al-bound P (p < 0.001) with up to 15.6 kg P ha−1. Moreover, the ash increased Olsen-P by up to two times. There was a strong relationship between the concentrations of Olsen-P and Al-bound P (R2 = 0.83, p < 0.001) as well as Fe-bound P (R2 = 0.74, p = 0.003), suggesting that the ash application resulted in an increased amount of relatively soluble P associated with hydroxy-Al and hydroxy-Fe compounds. Further, there was an 18 % increase in P uptake by trees in the ash treatment. By contrast, repeated N fertilization, with or without ash, reduced Olsen-P. The lower P extractability was concomitant with a 39 % increase in plant P uptake in the N treatment, which indicates elevated P uptake in response to higher N availability. Hence, the application of wood ash increased Al-bound P, easily available P, and P uptake. N fertilization, while also increasing tree P uptake, instead decreased easily available P and did not cause a shift in soil P speciation