Filtern
Erscheinungsjahr
Dokumenttyp
Schlagworte
- CONSENS (4)
- Geosynthetics (3)
- SAXS (3)
- Exposure (2)
- Geotextiles (2)
- MOUSE (2)
- Marine littering (2)
- Online NMR Spectroscopy (2)
- PFAS (2)
- Process Analytical Technology (2)
- Synchrotron (2)
- Additive Manufacturing (1)
- Additive manufacturing (1)
- Alkali-activated slag (1)
- Artificial ageing (1)
- Au NPs (1)
- BAMline (1)
- BESSY (1)
- Betriebspunktoptimierung (1)
- Bottom ash (1)
- CIS (1)
- CO2 separation membranes (1)
- COK-12 (1)
- CdTe (1)
- Chemical recycling (1)
- Chemisches Recycling (1)
- Circular economy (1)
- Cognitive performance (1)
- Computertomographie (1)
- Contamination (1)
- Continuous Manufacturing (1)
- Continuous processes (1)
- Data Fusion (1)
- Degradation (1)
- Digital X-ray detector (1)
- Digital radiography (1)
- Drawings (1)
- Dynamic surface leaching test (1)
- Echtzeitoptimierungsverfahren (1)
- Egyptian blue (1)
- Electron microscopy (1)
- Elemental Iron (1)
- Elemental imaging (1)
- Emission (1)
- FSDC (1)
- Fe (1)
- Fluorination (1)
- Fluorine (1)
- Fungus (1)
- GF-MAS (1)
- Gold (1)
- Graphene Oxide (1)
- Groundwater remediation (1)
- HR-CS-GFMAS (1)
- Haynes 282 (1)
- Hierarchically porous (1)
- High specific surface area (1)
- Holzschutz (1)
- Hydroxyapatite (1)
- Idiopathic environmental intolerance (1)
- Industrial and Manufacturing Engineering (1)
- Inorganic polymers (1)
- Iron speciation (1)
- Iterative real-time optimization (1)
- Ivory (1)
- Kulturgut aus Holz (1)
- LC-MS/MS (1)
- LD-Schlacke (1)
- Large-pore (1)
- Laser powder bed fusion (1)
- Laser printer (1)
- Laser printer emission (1)
- Leaching tests (1)
- Life cycle analysis (1)
- Life cycle thinking (1)
- Long-term Performance (1)
- Lung function (1)
- MYCN (1)
- Magnetoresistance (1)
- Magnetosensor (1)
- Mass-spectrometry (1)
- Measurement uncertainty (1)
- Mechanical processing (1)
- Melt-pool-monitoring (1)
- Mesocellular foam (1)
- Mesoporous Silica (1)
- Mesoporous silica (1)
- Messunsicherheit (1)
- Microplastic (1)
- Mining (1)
- Modifier adaptation (1)
- Modifier-Adaptation (1)
- Multiple chemical sensitivity (1)
- Multivariate Data Analysis (1)
- Müllverbrennung (1)
- NIR Spectroscopy (1)
- NMR Spectroscopy (1)
- Near Infrared Spectroscopy (1)
- Nonferrous slag (1)
- Nonstoichiometry (1)
- Nuclear Magnetic Resonance (1)
- OMS (1)
- Optical tomography (1)
- Ordered mesoporous silica (1)
- Oxyfuel-Verbrennung (1)
- Oxygen evolution reaction (1)
- Paints (1)
- Permeability (1)
- Permeable Reactive Barrier (1)
- Petzite (1)
- Photocatalysis (1)
- Photovoltaic (1)
- Plant pathogen (1)
- Plant-model mismatch (1)
- Plastic waste (1)
- Pore size tailoring (1)
- Porous materials (1)
- Process Industry (1)
- Products and production systems (1)
- Provenance (1)
- Prozess-Steuerung (1)
- Prozessanalytik (1)
- Pyrolyse (1)
- Pyrolysis (1)
- Reactor control (1)
- Real-time process monitoring (1)
- Real-time quality control (1)
- Recycling (1)
- Resource efficiency (1)
- Resources (1)
- Respiratory health (1)
- Robocasting (1)
- SDC (1)
- SPM (1)
- SR-FF-microXRF (1)
- SR-XRF (1)
- Samarium doped ceria (1)
- Scavenging effect of iron (1)
- Scintillator (1)
- Silica (1)
- Silver stylus (1)
- Simulation (1)
- Small angle scattering (1)
- Solid-State Complexes (1)
- Solvolyse (1)
- Solvolysis (1)
- Spark plasma sintering (1)
- Standardization (1)
- Subjective complaints (1)
- Synchrotron instrumentation (1)
- Synchrotron radiation (1)
- Tantalum oxyfluorides (1)
- Thermography (1)
- Thin film modules (1)
- Trace elements (1)
- Tricalciumsilikat (1)
- Tumor metabolism (1)
- Ultrafine particles (1)
- Utilisation (1)
- Virtual metrology (1)
- Virtuelle Messtechnik (1)
- Virulence (1)
- WWTP (1)
- Waste management (1)
- Water filtration (1)
- White beam topography (1)
- X-ray Color Camera (1)
- X-ray absorption near-edge structure (1)
- X-ray absorption spectroscopy (1)
- X-ray scattering (1)
- XANES spectroscopy (1)
- XRF (1)
- XRF analysis (1)
- Zement (1)
Organisationseinheit der BAM
- 4 Material und Umwelt (11)
- 1 Analytische Chemie; Referenzmaterialien (9)
- 4.3 Schadstofftransfer und Umwelttechnologien (8)
- 1.4 Prozessanalytik (5)
- 6 Materialchemie (5)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (5)
- 1.1 Anorganische Spurenanalytik (3)
- 7 Bauwerkssicherheit (2)
- 7.1 Baustoffe (2)
- 1.7 Organische Spuren- und Lebensmittelanalytik (1)
Paper des Monats
- ja (1)
The structures and properties of silver selenide samples strongly depend on the method of preparation. Thin films prepared by pulsed laser deposition (PLD) contain lamellae of two low-temperature modifications of Ag2Se whose structures were analyzed in detail by electron microscopy techniques. Besides the stable and known Naumannite-type phase (LT1), a metastable phase was observed (LT2), and the phase transformation was examined in situ. Via cooling and annealing, LT2 becomes dominant in thin films, thus enabling solving the structure of LT2 by electron diffraction. These experiments and HRTEM point to an Acanthite-type (stable low-temperature modification of Ag2S) structure of LT2. Rapid-quenching procedures were applied for the first synthesis of LT2 as bulk sample. Depending on the conditions of melt spinning experiments, well-defined products were formed. In one series, we found a separation of LT1 and LT2 into distinct morphologies, i.e. microspheres and dendrites, respectively. The results on the magnetoresistance of the rapidly quenched materials support previous work.
Phoenician ivory objects (8th century B.C., Syria) from the collections of the Badisches Landesmuseum, Karlsruhe, Germany, have been studied with full field X-ray fluorescence microimaging, using synchrotron radiation (SR-FF-microXRF). The innovative Color X-ray Camera (CXC), a full-field detection device (SLcam), was used at the X-ray fluorescence beamline of the ANKA synchrotron facility (ANKA-FLUO, KIT, Karlsruhe, Germany) to noninvasively study trace metal distributions at the surface of the archeological ivory objects. The outstanding strength of the imaging technique with the CXC is the capability to record the full XRF spectrum with a spatial resolution of 48 µm on a zone of a size of 11.9 × 12.3 mm² (264 × 264 pixels). For each analyzed region, 69696 spectra were simultaneously recorded. The principal elements detected are P, Ca, and Sr, coming from the ivory material itself; Cu, characteristic of pigments; Fe and Pb, representing sediments or pigments; Mn, revealing deposited soil minerals; Ti, indicating restoration processes or correlated with Fe sediment traces; and Au, linked to a former gilding. This provides essential information for the assessment of the original appearance of the ivory carvings. The determined elemental maps specific of possible pigments are superimposed on one another to visualize their respective distributions and reconstruct the original polychromy and gilding. Reliable hypotheses for the reconstruction of the original polychromy of the carved ivories are postulated on this basis.
Dual-phase membranes for high-temperature carbon dioxide Separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement These membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce_(0.8) Sm_(0.2) O_(2-d) (SDC) and Ce_(0.8)Sm_(0.19)Fe_(0.01)O_(2-d) (FSDC) ceramic powders were used to form the skeleton in dual-Phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.
A similar secretome disturbance as a hallmark of non-pathogenic Botrytis cinerea ATMT-mutants?
(2019)
The gray mold fungus Botrytis cinerea is a necrotrophic pathogen able to infect
hundreds of host plants, including high-value crops such as grapevine, strawberry and tomato. In order to decipher its infectious strategy, a library of 2,144 mutants was generated by random insertional mutagenesis using Agrobacterium tumefaciensmediated transformation (ATMT). Twelve mutants exhibiting total loss of virulence toward different host plants were chosen for detailed analyses. Their molecular characterization revealed a single T-DNA insertion in different loci. Using a proteomics approach, the secretome of four of these strains was compared to that of the parental strain and a common profile of reduced lytic enzymes was recorded. Significant variations in this profile, notably deficiencies in the secretion of proteases and hemicellulases, were observed and validated by biochemical tests. They were also a hallmark of the remaining eight non-pathogenic strains, suggesting the importance of these secreted Proteins in the infection process. In the twelve non-pathogenic mutants, the Differentiation of infection cushions was also impaired, suggesting a link between the Penetration structures and the secretion of proteins involved in the virulence of the pathogen.
A general method to carry out the fluorination of metal oxides with poly(tetrafluoroethylene) (PTFE, Teflon) waste by spark plasma sintering (SPS) on a minute scale with Teflon is reported. The potential of this new approach is highlighted by the following results. i) The tantalum oxyfluorides Ta3O7F and TaO2F are obtained from plastic scrap without using toxic or caustic chemicals for fluorination. ii) Short reaction times (minutes rather than days) reduce the process time the energy costs by almost three orders of magnitude. iii) The oxyfluorides Ta3O7F and TaO2F are produced in gram amounts of nanoparticles. Their synthesis can be upscaled to the kg range with industrial sintering equipment. iv) SPS processing changes the catalytic properties: while conventionally prepared Ta3O7F and TaO2F show little catalytic activity, SPS-prepared Ta3O7F and TaO2F exhibit high activity for photocatalytic oxygen evolution, reaching photoconversion efficiencies up to 24.7% and applied bias to photoconversion values of 0.86%. This study shows that the materials properties are dictated by the processing which poses new challenges to understand and predict the underlying factors.
In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-mXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its K alpha XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution.
Per- and polyfuoroalkyl substances (PFAS) are emerging organic pollutants and can occur in surface and groundwater. To identify the degree of pollution in surface water with PFAS, often targeted HPLC–ESI–MS/MS has been employed in which commonly 30–40 compounds are analyzed. However, other PFAS and organofuorines remain undetected. We sampled surface water of the river Spree and the Teltow Canal in Berlin, Germany, which are afected by the efuent discharge of wastewater treatment plants. Here, we employed high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) for measuring extractable organofuorines (EOF) and compared in a mass balance approach the total fuorine to the identifed and quantifed PFAS from the targeted analysis. The analysis highlights that the EOF are in the range expected for an urban river system (Winchell et al. in Sci Total Environ 774, 2021). However, downstream of an efuent discharge, the EOF increased by one order of magnitude, e.g., 40.3 to 574 ng F L−1, along the Teltow Canal. From our target analytes, mostly short-chained perfuorinated carboxylic acids and sulfonates occur in the water, which however makes up less than 10% of the EOF. The increase in EOF in the Teltow Canal correlates well with the increase of perfuorohexanoic acid (PFHxA), indicating that PFHxA is characteristic for the discharged EOF but not responsible for the increase. Hence, it points to PFHxA precursor discharge. The study highlights that EOF screening using HR-CS-GFMAS is necessary to identify the full scale of pollution with regard to PFAS and other organofuorines such as pharmaceutical compounds from the efuent of WWTPs.
Almost 500 municipal solid waste incineration plants in the EU, Norway and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place.
A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances.
Das mechanische Recycling von Kunststoffen ist seit Jahren großtechnisch etabliert, hat aber technische und ökonomische Grenzen. Durch Verfahren des chemischen Recyclings gelangt man zurück zu Monomeren oder den Rohstoffen, so dass am Ende wieder Neuware für alle Einsatzgebiete von Kunststoffen entsteht. Die Vielfalt von chemischen Recyclingverfahren ist groß. Die Kapazitäten der Anlagen sind heute noch gering und die Wirtschaftlichkeit wird stark vom Ölpreis beeinflusst.
Die Rentabilitätsgrenze liegt derzeit bei einem Preis zwischen 50 und 60 US-$ pro Barrel.
Industrial-scale mechanical recycling of plastics has been established for years, but has technical and economic limits. Chemical recycling processes lead back to monomers or to the raw materials, so that in the end new goods can be produced for all areas of application of plastics. The variety of chemical recycling processes is large. The capacities of the plants are still low today. The profitability of the plants is strongly influenced by the price of oil; the profitability limit is currently between 50 and 60 US $ per barrel.
X-ray topography is a well known imaging technique to characterise strain and extended defects in single crystals. Topographs are typically collected on X-ray films. On the one hand such photographic films show a limited dynamic range and the production of films will be discontinued step by step in the near future. On the other hand new imaging detectors improved for X-ray tomography become more and more attractive even for topography because of increasing resolution, dynamic range, speed and active area. In this paper we report about the upgrade of the TOPOTOMO beamline at the synchrotron light source ANKA, Research Centre Karlsruhe, with a high resolution digital camera for the topography use.
Ultrafine particles emitted from laser printers are suspected to elicit adverse health effects. We performed 75-minute exposures to emissions of laser printing devices (LPDs) in a standardized, randomized, cross- over manner in 23 healthy subjects, 14 mild, stable asthmatics, and 15 persons reporting symptoms associated with LPD emissions. Low-level exposures (LLE) ranged at the particle background (3000 cm−3) and High-level exposures (HLE) at 100 000 cm−3. Examinations before and after exp sures included spirometry, body plethysmography, transfer factors for CO and NO (TLCO, TLNO), bronchial and alveolar NO, cytokines in serum and nasal secretions (IL-1β, IL-5, IL-6, IL-8, GM-CSF, IFNγ, TNFα), serum ECP, and IgE. Across all participants, no statistically significant changes occurred for lung mechanics and NO. There was a decrease in volume-related TLNO that was more pronounced in HLE, but the difference to LLE was not significant. ECP and IgE increased in the same way after exposures. Nasal IL-6 showed a higher increase after LLE. There was no coherent pattern regarding the responses in the participant subgroups or single sets of variables. In conclusion, the experimental acute responses to short but very high-level LPD exposures were small and did not indicate clinically relevant effects compared to low particle number concentrations.
Die Mikro- und Nanotechnologie gehört zu den Schlüsseltechnologien des 21. Jahrhunderts mit hohen Wachstumsprognosen, wie auch die im Auftrag des BMBF durchgeführte Studie “Nanotechnologie als wirtschaftlicher Wachstumsmarkt” von 2004 ausführlich darstellt. Aus diesem Trend resultiert ein steigender Bedarf an Messsystemen, die Nanostrukturen prozessnah bzw. im Fertigungsprozess charakterisieren können. Virtuelle Messgeräte liefern Erkenntnisse zur Entwicklung neuartiger Messsysteme, Analyse und Optimierung bestehender Verfahren sowie die Bestimmung der Messunsicherheit und modellbasierten Korrektur systematischer Fehler. Der virtuelle Messprozess umfasst neben dem Messmittel auch die Probe und die Wechselwirkungen zwischen beiden. In diesem Beitrag werden virtuelle Messgeräte vorgestellt sowie deren Anwendung diskutiert.
We performed spatially resolved synchrotron-induced x-ray fluorescence analyses (SY-XRF) of five silverpoint drawings from the famous `Karlsruhe sketchbook´ and a silverpoint, which is assumed to be an original one used by the Renaissance artist Hans Baldung Grien (1484-1545) himself. The silverpoint, one out of a very small number of ancient styli conserved nowadays, is fixed on the so-called `Karlsruhe sketchbook´. Measurements were executed at the FLUO-TOPO beamline at the electron storage ring ANKA. It has been shown, that SY-XRF at this beamline is nondestructive and sensitive enough for the analysis of minor and major elements in the silver strokes. This study provides new insights into this graphical technique and ancient drawing instruments: results are that three drawings have been created with a common type of silverpoint containing about (10.4 ± 0.7) wt% of Cu. In all the cases, Hg at a 10% level by weight was identified in the strokes. Presence of Hg is not due to the original silver alloy, but is a result of a general alteration phenomenon of silverpoint drawings. This fact is confirmed by the analysis of the original silverpoint, which contains only small traces of Hg. The result for the copper content of the silverpoint (10.4 ± 1.7) wt% is in good agreement with that of these three drawings. It is supposable that the silverpoint found attached today served for the creation of the corresponding drawings. Moreover, the graphical technique of Baldung is found to be continual over three decades. Only one very late drawing dated to 1543 was probably realized with another silverpoint, containing about 3 wt% of Cu. This difference in the chemical composition of drawings from the late period might be used as a more precise dating indicator of Baldung drawings that are not clearly attributed to a certain period.
Studies by Synchrotron Radiation-X-Ray Fluorescence (SR-XRF) for the search of the presence of trace elements like Sb, Sn, Te and Pb in archaeological metallic objects found on the territory of Romania-old coins and Bronze Age jewelry, aimed to determine the provenance of the gold used in their manufacture. The results are compared with the detailed elemental composition of alluvial or primary gold samples, obtained by the same technique. This work attempted to establish the origin of the gold used for the mint of two different types of koson coins. We found that the kosons with monogram are made of refined gold, while the one used for the kosons without monogram is mainly alluvial. The gold used in the manufacture of the Calarasi Vulchitrun-type disk and the Tauteu hair ring is also of alluvial origin.
Dispersions of very small non-magnetic metal particles or inclusions in a non-magnetic semiconductor matrix are well known to produce unusually large and linear magnetoresistance effects. So far these materials were limited to the binary silver-rich chalcogenides Ag2Se and Ag2Te. In this contribution Ag3AuTe2 was selected as a first candidate for a ternary matrix material, thus offering enhanced capabilities for the generation of heterogeneous microstructure and spatially varying composition on the nanoscale. In gold-rich Ag3Au1.1Te2 two kinds of inhomogeneities are present, namely Au deposits with a size on the micron scale and an inhomogeneous distribution of Au and Ag within the matrix. The matrix consists of micron-sized grains with the structure type of Ag3AuTe2 as studied by electron microscopy. Like the binary silver chalcogenide phases, the material also shows a large and linear magnetoresistance effect. The transversal magnetoresistance effect was measured between 20 K and 270 K in magnetic fields up to B = 5 T. The results are discussed on the basis of existing models for a large and linear positive MR effect.
Mechanically stable structures with interconnected hierarchical porosity combine the benefits of both small
and large pores, such as high surface area, pore volume, and good mass transport capabilities. Hence, lightweight micro-/meso-/macroporous monoliths are prepared from ordered mesoporous silica COK-12 by means of spark plasma sintering (SPS, S-sintering) and compared to conventionally (C-) sintered monoliths. A multi-scale model is developed to fit the small angle X-ray scattering data and obtain information on the hexagonal lattice parameters, pore sizes from the macro to the micro range, as well as the dimensions of the silica population. For both sintering techniques, the overall mesoporosity, hexagonal pore ordering, and amorphous character are preserved. The monoliths' porosity (77–49%), mesopore size (6.2–5.2 nm), pore volume (0.50–0.22 g cm-3
), and specific surface area (451–180 m2 g-1) decrease with increasing processing temperature and pressure. While the difference in porosity is enhanced, the
structural parameters between the C-and S-sintered monoliths are largely converging at 900 C, except for the mesopore size and lattice parameter, whose dimensions are more extensively preserved in the
S-sintered monoliths, however, coming along with larger deviations from the theoretical lattice. Their higher mechanical properties (biaxial strength up to 49 MPa, 724 MPa HV 9.807 N) at comparable porosities and ability to withstand ultrasonic treatment and dead-end filtration up to 7 bar allow S-sintered monoliths to reach a high permeance (2634 L m-2 h-1 bar-1), permeability (1.25 x 10^-14 m2), and ability to reduce the chemical oxygen demand by 90% during filtration of a surfactant-stabilized oil in water emulsion, while indicating reasonable resistance towards fouling.
The baroque epitaph Reyer (1704) at the St. Laurentius church in Tönning was treated with carbolineum as a wood preservation agent in 1903. The subsequent constant migration of carbolineum through the layers of paint to the surface has had a detrimental effect on the aesthetic appearance of the epitaph. Carbolineum is an oily, water-insoluble, flammable, dark brown mixture of coal tar oil components. Due to its content of polycyclic aromatic hydrocarbons (PAH), which are classified as carcinogenic and harmful to the environment, the use of carbolineum has been forbidden. The aim of the project is to develop an exemplary Conservation treatment (hat will reduce the toxic contents of the historical wooden object. The new method should be applicable to similar objects that are also contaminated with carbolineum. The historic carbolineum was identified by the GC-MS method and the X-Ray computed tomography revealed the biological wood damage and previous restoration measures. Several decontamination methods such as the extraction with supercritical C02, with dichloromethane vapour/fluids, with 1,3-dioxolane or with petrol ether by vaccum impregnation were investigated. This project is founded by the Deutsche Bundesstiftung Umwelt (DBU).
Slags from the nonferrous metals industry have great potential to be used as feedstocks for the production of alkali-activated materials. Until now, however, only very limited information has been available about the structural characteristics of these materials. In the work presented herein, synthetic slags in the CaO–FeOx–SiO2 system, representing typical compositions of Fe-rich slags, and inorganic polymers (IPs) produced from the synthetic slags by activation with alkali Silicate solutions have been studied by means of X-ray absorption near-edge structure (XANES) spectroscopy at the Fe K-edge. The iron in the slags was largely Fe2+, with an average coordination number of approximately 5 for the iron in the amorphous fraction. The increase in average oxidation number after alkali-activation was conceptualized as the consequence of slag dissolution and IP precipitation, and employed to calculate the degrees of reaction of the slags. The degree of reaction of the slags increased with increasing amorphous fraction. The iron in the IPs had an average coordination number of approximately 5; thus, IPs produced from the Fe-rich slags studied here are not Fe-analogs of aluminosilicate geopolymers, but differ significantly in terms of structure from the latter.
Large-pore ordered mesoporous silica (OMS) COK-12, analogous to the well-known SBA-15, but synthesized in a more environmentally friendly way and exhibiting a shorter plate-like structure, was grafted with different amounts of graphene oxide (GO) for the first time in an inexpensive and rapid process, that was successfully upscaled. Samples were examined with nitrogen sorption analysis, SAXS, Raman spectroscopy, XPS, and zeta potential analysis. Adsorption experiments with the cationic dye methylene blue (MB) were conducted on the grafted materials and on pure COK-12, taking into account the influence of initial dye concentration (30–600 mg L-1), adsorbent dosage (0.2–14 g L-1), contact time (0.3–300 min), solution pH (4 10), and influence of salts and temperature (0–1 M NaCl, 80 C) to simulate industrial dye effluent. The adsorption process was found to be represented best by the Langmuir isotherm model, i.e., adsorption is a monolayer process. The calculated maximum Adsorption capacities were found to be 20.2 and 197.5 mg g-1 at dosages of 5 and 0.5 g L-1 for pure COK-12 and COK-12 grafted with 50 wt% GO, respectively, at pH 5.65 and MB concentration of 100 mg L-1.
Adsorption kinetics were found to follow the pseudo-second order model, i.e., chemisorption is the rate controlling step. The adsorption performances could be well preserved at simulated dye effluent.
Desorption was found to be most effective with hydrochloric acid. The COK-12 grafted with GO presented in this work shows superior adsorption properties in comparison to other grafted OMS materials. In addition, grafting with GO remarkably improved the stability of COK-12 in aqueous solution.