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The consensus is growing for the UN sustainable development goals regarding responsible consumption, production, and climate actions. Because of growth towards a digital society (“industry 4.0 revolution”), it is needed to have our resources and economies to be circular. The success also depends on appropriate management of critical raw materials, such as Rare Earth Elements (REEs). Here, a cost-effective recycling method for the recovery of single REEs from fluorescent powder (FP) with end-of-life lamp e-waste is presented with the additional benefit of having a much less environmental impact than mining. The recycling method involves a carefully designed sequential digestion of two phosphor components (YOX and LAP) and treating their leachates separately under specific hydrometallurgical conditions. The phosphors were targeted for Yttrium (Y), Europium (Eu), Terbium (Tb), Lanthanum (La), Cerium (Ce), and Gadolinium (Gd). On trace REEs basis, the leaching process with the FP showed >95% recovery for Eu, La, Ce, Y and Tb. The effective recycling was achieved to >99% purity for Y, Eu, and Tb in 1, 25, and 55 liquid-liquid extraction stages, respectively. To our knowledge, this is one of the first methods to leach and separate Tb from FP e-waste with near quantitative leaching efficiency and >99% purity.

In biomass gasification processes, the formation and handling of tars are of major concern. Robust and versatile analytical tools are needed to on-line monitor tar compound concentrations in process gases from lab- to industrial scale. This study addresses the development and application of an on-line UV-Vis method, based on a liquid quench sampling system. The high sensitivity of this method allows to detect UV-Vis active tar compounds in the low ppmv region. Recorded spectra from the liquid phase were analyzed for their tar composition by means of a classical least squares (CLS) and partial least squares (PLS) approach. The developed method was applied to two case studies, involving a lab-scale tar reformer and a pilot-scale gas scrubber. Quantification results in gases with limited complexity in tar composition showed good agreement with off-line reference methods (GC-FID). The case studies show that the developed method is a rapid, sensitive tool that can be applied for qualitative process monitoring with the added benefit of quantification in gases with a limited number of tar compounds. (C) 2016 Elsevier Ltd. All rights reserved.

Fly ash (FA) is a by-product of power, and incineration plants operated either on coal and biomass, or on municipal solid waste. FA can be divided into coal fly ash, obtained from power plant burning coal, flue gas desulphurisation FA, that is, the by-product generated by the air pollution control equipment in coal-fired power plants to reduce the release of SO2, biomass FA produced in the plants for thermal conversion of biomass and municipal solid waste incineration (MSWI) FA, that is, the finest residue obtained from the scrubber system in a MSWI plant. Because of the large amount produced in the world, fly ash is now considered the world's fifth largest material resource. The composition of FA is very variable, depending on its origins; then, also pollutants can be very different. In this frame, it is fundamental to exploit the chemical or physical potentials of FA constituents, thus rendering them second-life functionality. This review paper is addressed to FA typology, composition, treatment, recycling, functional reuse and metal and organic pollutants abatement. Because of the general growing of environmental awareness and increasing energy and material demand, it is expected that increasing recycling rates will reduce the pressure on demand for primary raw materials, help to reuse valuable materials which would otherwise be wasted and reduce energy consumption and greenhouse gas emissions from extraction and processing.

Ni:a-C:H thin films obtained by reactive sputtering processes were investigated using EXAFS and subsequent wavelet analysis. Depending on overall thin film deposition conditions, the clusters of Ni in Ni:a-C:H can appear as fcc-Ni or as a non-fcc-Ni phase, such as hcp-Ni or Ni3C. While hcp-Ni and Ni3C are hardly distinguishable by XRD, the EXAFS analysis can reveal if carbon is the nearest neighbour of Ni or not, thus if Ni3C is present or hcp-Ni. Our study showed that wavelet transformation analysis of the EXAFS data is necessary to discriminate clearly between hcp-Ni and Ni3C regarding the presence or absence of carbon coordination shells around the X-ray absorbing Ni atoms. Furthermore, we are confident to have identified Ni3C in our thin films, however, we cannot exclude the possibility of the co-existence of hcp-Ni. Finally, calculations of XRD peaks of hcp-Ni and Ni3C showed that a discrimination of these two crystal phases might be feasible when the crystallite size is increased beyond 40 nm.

The purpose of this study was to investigate the sulphur deactivation mechanism during an industrial methanation process, but also after catalyst regeneration. In the present work we extended our computational investigations to study the adsorption of sulphur poisoning compounds on the Ni/Al 2 O 3 catalyst. The focus was to study possible catalyst changes and thus the modified catalytical behaviour of the nickel particles, as well as to see differences in the poisoning behaviour, when sulphur adsorbs either on the Ni particle or on the support. This was done using Density Functional Theory calculations (StoBe) with cluster model and non-local functional (RPBE) approach. For modelling the catalyst, an Al 15 O 40 H 35 cluster has been selected representing the γ-Al 2 O 3 (1 0 0) surface, and Ni metal particles of different sizes were cut from a Ni(1 0 0) surface and deposited on the Al 15 O 40 H 35 cluster. Several poisoning agents have been found to be stable on both Ni clusters and alumina support such as COS, H 2 S, or hydrogen thiocarbonates.

Ni-based catalysts are prone to deactivation (poisoning) of their active surface sites by sulphur and carbon species contained in the gas fed to the reactor. This study focuses on Ni/Al2O3-based catalyst samples which had allegedly been deactivated by sulphur poisoning. The samples had been collected from a 10 kW methanation reactor fed with producer gas from the industrial biomass gasifier in Gussing (Austria). The samples allowed intensive investigation using several analytical tools to identify the chemical nature (inorganic, organic) of the S-poisoning species. Temperature-programmed oxidation (TPO) allowed quantification of the sulphur content, but not the identification of the S species responsible. S 2p X-ray photoelectron spectroscopy (XPS) pointed at the presence of sulphide and sulphate, but the data were too noisy to reach more specific conclusions. Ni K-edge X-ray absorption spectroscopy (XAS) in the fine structure (EXAFS) region suggested the presence of elemental or thiophenic sulphur, but the contribution was masked heavily by other backscattering paths. Only S Kedge analysis in the near edge (XANES) region showed unambiguously that the catalyst could not have been deactivated by inorganic H2S only. This conclusion is supported by S K-edge XANES results with model catalysts which had either been poisoned by H2S or thiophene (C4H4S), representing a cyclic, aromatic S compound. Short-term H2S poisoning in the absence of air led to a white-line position characteristic for sulphide (2470 eV), whereas with thiophene the white-line position started at 3 eV higher energy. The XANES signatures changed with the catalyst samples after contacting air, but remained unique for each of the two S-poison types studied here. (C) 2009 Elsevier B.V. All rights reserved.

Keywords: Evaporation Rates ; Metal Removal ; Speciation ; Vaporization ; Behavior ; Sulfide Reference EPFL-ARTICLE-159665doi:10.1002/adem.200800324View record in Web of Science Record created on 2010-11-30, modified on 2016-08-09

Metallic Ni nanopowder (Ni-0) was monitored during 23 h of carburization (2CO + 3Ni(0) - Ni3C + CO2, T = 265 degrees C) using Ni K-edge X-ray absorption spectroscopy. X-ray diffraction analysis made afterward at room temperature revealed 28 +/- 3% Ni3C among 72% unreacted Ni-0. The chi(k) data recorded during carburization showed small changes at low k indicative of carbon backscattering. The identification of carbon was possible with wavelet transform analysis after eliminating the integral contribution from the unreacted Ni-0 phase using experimental chi(k) data collected during methanation (CO + 3H(2) -> CH4 + H2O) at T = 265 degrees C. The Fourier-transformed chi(k) data recorded during carburization revealed destructive interference between signals from Ni atoms in slightly different (Ni-0, Ni3C) environments. The interference effect mainly lowered the peak amplitude of the first two Ni-Ni coordination shells compared to metallic Ni at T = 265 degrees C and it propagated very slowly with increasing carburization run time. In simulation of the amplitude lowering of the first Ni-Ni peak by destructive interference as a function of the carburization run time, it followed that the carbon atoms migrate into the Ni-0 particle lattice according to the diffusion-induccd grain boundary motion advocated in the literature.

Profiles of the major sulfur functional groups in mature Norway spruce wood tissue have been established for the first time. The big challenge was the development of a method suitable for sulfur speciation in samples with very low sulfur content (

Fly ash is commonly deposited in special landfills as it contains toxic concentrations of heavy metals, such as Zn, Pb, Cd, and Cu. This study was inspired by our efforts to detoxify fly ash from municipal solid waste incineration by thermal treatment to produce secondary raw materials suited for reprocessing. The potential of the thermal treatment was studied by monitoring the evaporation rate of zinc from a certified fly ash (BCR176) during heating between 300 and 950 degreesC under different carrier gas compositions. Samples were quenched at different temperatures for subsequent investigation with X-ray absorption spectroscopy (XAS). The XAS spectra were analyzed using principal component analysis (PCA), target transformation (TT), and linear combination fitting (LCF) to analyze the major Zn compounds in the fly ash as a function of the temperature. The original fly ash comprised about 60% zinc oxides mainly in the form of hydrozincite (Zn-5(OH)(6)(CO3)(2)) and 40% inerts like willemite (Zn2SiO4) and gahnite (ZnAl2O4) in a weight ratio of about 3:1. At intermediate temperatures (550750 degreesC) the speciation underlines the competition between indigenous S and Cl with solid zinc oxides to form either volatile ZnCl2 or solid ZnS. ZnS then transformed into volatile species at about 200 degreesC higher temperatures. The inhibiting influence of S was found absent when oxygen was introduced to the inert carrier gas stream or chloride-donating alkali salt was added to the fly ash.

The gasification reaction of fir charcoal with CO2 was studied by isothermal thermogravimetric analysis under kinetic control. The derived reaction rate (r = dX/dt) as a function of the converted carbon mass (X) was compared with random pore model predictions and found to be much higher at elevated conversion levels than predicted by theory. Similar enhanced reaction rate behaviour was evidenced after removing the natural alkali catalyst from the charcoal by acid washing, suggesting that with untreated charcoal the late reaction rate contribution stems from both, catalytic and additional structure effects. Literature attributes the unpredicted late reaction rate behaviour to the disintegration of the porous char particle into small fragments, which, in line with percolation theory predictions, seems to occur only after a critical conversion level has been reached. However, our gasification data reveal a gradual rise in the charcoal reactivity thereafter, suggesting a breaking up (embrittlement) of the solid phase accompanied by the exposure of fresh surface area from fracturing. The original random pore model derivation given by Bhatia and Perlmutter is extended to account also for these peculiarities and the resulting kinetic relation described our reaction rate data well over the entire conversion range. (C) 2002 Elsevier Science Ltd. All rights reserved.

The experimentally observed rise in the single pass methanol production with CO2 and H-2 (T = 200 degreesC, P = 4.3 bar) by in situ product removal over a perm-selective Nafion (R) membrane is verified by model simulations. For this purpose, software was developed which addresses the two rivalling processes (synthesis and permeation) for given catalyst activity and permeation performance of the membrane. The program predicts the production rate of all the reactor gas components leaving the reactor by explicit integration of the gas component and (reactor and mantle) space specific differential rate equations along the symmetry axes of the tubular membrane reactor. The activity of the CO2-tolerant catalyst used was characterized independently by kinetic model analysis; the experimentally determined permeation performance of the membrane for the various reactant gas components by Arrhenius type temperature dependencies. The model confirmed the membrane reactor results satisfactorily well. It was estimated that with 10 mum thin membrane surfaces implemented in commercial methanol synthesis plants and operated under technically relevant conditions (T = 200 degreesC, P = 40 bar, GHSV = 5000 h(-1)), the single pass reactor yield improves by 40% and that the additional costs for the membrane material are two production months only. (C) 2001 Elsevier Science B.V. All rights reserved.

In view of the laboratory tests performed at PSI with a Nafion tubular membrane reactor module for the catalysed methanol synthesis with CO2 and H-2 at 200 degrees C, the mechanical stability of a commercially available Nafion hollow fiber was tested at elevated temperatures (T=160-200 degrees C) and pressures (P

This chapter reviews fly ash typology, composition, treatment, deposition, recycling, functional re-use, and metals and organic pollutants abatement. Fly ash is a by-product of power and incineration plants operated either on coal and biomass, or municipal solid waste. The growing of environmental awareness and increasing energy and material demand will foster recycling. Recycling will help to reuse valuable materials which would otherwise be wasted, and reduce energy consumption and greenhouse gas emissions from extract ion and processing. Fly ash is world’s fifth largest material resource because of the large amount of ash produced in the world. Fly ash can be classified into several categories: coal fly ash obtained from power plant burning coal; flue gas desulphurisation fly ash, that is the byproduct generated by the air pollution control equipment in coal-fired power plants to prevent (reduce) the release of SO2; biomass fly ash produced in the thermal conversion of biomass; and municipal solid waste incineration (MSWI) fly ash, that is the finest residue obtained from the scrubber system in a municipal solid waste incineration plant.

Thermal treatment is a promising way for the decontamination and inertization of residues from waste incineration. The evaporation of heavy metal compounds thereby is of great significance. It is the goal of this work to identify, by analyzing evaporation rates, the predominant thermochemical reactions of the heavy metals with other constituents of fly ash, with respect to volatilization. To this end, experiments were performed with fly ash from a municipal solid waste (MSW) incineration plant as well as with synthetic powder mixtures in the temperature range of 670−1000 °C. The rates of Cd, Cu, Pb, and Zn evaporation can be described accurately by a simple first-order rate law and a rate coefficient which itself follows an exponential temperature dependence analogous to the Arrhenius equation. The degrees (completeness) as well as the rates of evaporation of the heavy metals are markedly influenced by chlorides contained in the fly ash, largely as NaCl. Experiments with model substrates indicate that the...

Methanol synthesis from CO 2 and H 2 is a promising chemical energy storage reaction for hydrogen. The methanol yield of the synthesis is limited by the thermodynamic equilibrium at the temperatures required by state-of-the-art catalysts. Substantial conversion improvements would be achieved by selective product separation from the catalyst bed of a synthesis reactor. A perfluorinated cation exchange material (Nafion ® , DuPont) is evaluated for use as a vapour permeation membrane at temperatures up to 200°C. The permselectivities for methanol and water with respect to hydrogen depend on the counter ion in the polymer, and drop as a function of temperature. With respect to long term stability and performance, lithium is best suited as a counter ion, with permselectivities of 32 for water, and 5.6 for methanol, respectively. Permeability and permselectivity are found to increase with increasing partial pressures of both methanol and water vapours. The capability of the Li-Nafion membrane to separate products from a commercially available catalyst bed operating on CO 2 and H 2 at 200°C is demonstrated using a simple tubular membrane reactor module.

Waste incineration is a technology which is more than 100 years old. The technology was first introduced at the end of the 19th century to reduce the volume and mass of MSW in order to save landfill space. In a time when smoking stacks were synonymous with progress, nobody cared about the emissions from incinerators into the air. Only when air pollution became a high priority issue in the early 1980s was it found that MSW incinerators were in fact contributing substantially to the overall emission of air pollutants, notably of HO, dioxins and various heavy metals. Once this drawback to MSW incineration was acknowledged, legislation intervened and forced the environmental technology industry to develop suitable air pollution control (APC) technology, which in turn required that operators of incinerators invest large sums to limit the emission of acid gases, particulates and toxic trace compounds. The era of environmental technology from 1980 to 2000 has in fact brought down the emissions from incineration to levels that have made MSWI a minor contributor to air pollution for all emission categories [48].

The catalytic influence of major metal species found with waste wood (Na, K, Ca, Mg, Zn, Pb, Cu) was studied during the gasification of nitrate salt impregnated charcoal with CO2 at 800degreesC in the kinetically controlled regime. In contrast with literature, the respective reaction rate data were analysed over the entire carbon conversion (X) range by using extended kinetic relations to quantify catalyst metal-specific reaction rate contributions not accounted for by the original random pore model of Bhatia and Perlmutter. The kinetic analysis provided valuable insights in the underlying mechanisms. With alkali nitrate impregnated charcoal, it is demonstrated that the often found reaction rate maximum around X similar to 0.7 may merely reflect increasing catalytic activity resulting from alkali accumulation in the charcoal, superimposed on structural changes in the charcoal micropore domain. Impregnated earth-alkali nitrates revealed substantial activity as well, but only during the early gasification stage (X < 0.2), hereby, underlining their sintering propensity in combination with the localised deposition of the earth-alkaline nitrate salt in the former wood cells by the impregnation procedure. Added heavy metal nitrates revealed no activity, apart from lowering the charcoal reactivity over the entire conversion range by ca. 15% compared with the untreated charcoal, suggesting inhibition by covering, hence, blocking of otherwise accessible active charcoal surface sites and/or by deactivation of neighbouring indigenous alkali due to immobilisation at the heavy metal oxide surfaces formed during pyrolysis. The extended kinetic relation reproduced all of our reaction rate data well over the entire gasification stage, hereby, supporting the superposition of micropore domain and catalyst specific effects. (C) 2002 Elsevier Science Ltd. All rights reserved.

Successful management of secondary waste resources is essential for the viable circular economy. E-waste could serve as the potential urban mining source for the alternative supply chain of critical metals such as rare earth elements (REEs). The hydrometallurgical processes for REEs are mainly designed for primary mining. Conventional approaches lack sustainability and the economic- and value chain-based aspects that are significant in the current era with its increasing focus and pressure to reduce environmental impact. We have performed thermodynamic calculations to simulate the solution chemistry behaviour of REEs, such as Neodymium (Nd), Dysprosium (Dy), and Praseodymium (Pr) present in NdFeB magnets. The results suggested that one could exploit the different solubility of these REE hydroxides by controlling the pH value and separating the REEs further using extractive processes. In contrast to primary mining, the use of appropriate wet chemistry, extractive conditions with selective ligands and supported liquid membrane methods with secondary (urban) mining could open up more sustainable and economic recycling of rare earth magnets with reduced environmental impact and direct scalability.

Nickel iron oxide (NiFe2O4) has been tested as a combined catalyst precursor and oxygen transfer material for improved conversion of methane into syngas. Thermogravimetric measurements with simultaneous gas analysis have demonstrated the superior behavior of nickel iron oxide compared to iron oxide. The enhanced catalytic activity is attributed to the generation of fresh nickel surfaces in the course of the reduction of the metal oxide. This allows for a periodic in situ generation of fresh, catalytically active nickel. (C) 2006 Elsevier Ltd. All rights reserved.

Many efforts have been undertaken in past decades to minimize pollution from municipal solid waste incineration fly ash (MSWI FA). This residue is toxic, because of its high concentration of heavy metals, mainly Pb and Zn. A new method for heavy metals entrapment with MSWI FA was proposed recently. The method is based on the use of colloidal silica and it was applied to other FA typologies (flue gas desulfurization and coal fly ashes). The first results, in terms of material recovery, are very promising. The present paper is dedicated to the study of the mechanism of entrapment of heavy metals as promoted by the use of colloidal silica in the inertisation process by means of X-ray Absorption Spectroscopy (XAS) and by synchrotron-based XRD. Only XAS allowed focussing on the local environmental changes for Pb and Zn atoms on a molecular level. Chemical equilibrium calculations predict that, without silica, water-soluble Pb and Zn salts form stable phases, such as carbonates. XAS analysis showed that, despite carbonation of alkaline earth metals such as Ca, colloidal silica promotes the stabilisation of major heavy metals in phases other than carbonates and most likely in the more inert silicate form.