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Clays and clay minerals dissolve over a broad pH range, such as during sediment diagenesis and in a variety of applications, including nuclear waste storage, landfills, and geopolymer binders in the construction industry. The solubility depends on process parameters (pH, temperature, pressure, etc.) and material properties (phase content, clay mineral composition, particle size, etc.). Pretreatments such as calcination or severe grinding change the material properties and could enhance solubility, which is called activation. The aim of the current study was to determine the solubility of three different clay minerals after calcination (metakaolinite, metamontmorillonite, and metaillite) in high molar alkaline solutions (NaOH) up to 10.79 mol/L and pH = 14.73. Furthermore, the solubility of an Al(OH)3 powder in alkaline solution (NaOH) was analyzed, as it can be used to adjust the Si:Al ratio of geopolymer precursors. The residues of the clay minerals after the alkaline treatment were investigated to disclose potential alterations in their phase contents. Based on the results of the thermal and alkaline activation, conclusions about the suitability as geopolymer precursors were made. All clay minerals showed an increase in solubility proportional to the concentration of the alkaline solution. The solubility decreased in the order metakaolinite > metamontmorillonite > metaillite. Thereby, dissolution was incomplete for all three clay minerals (

Low-cost enzyme-free glucose sensors with partial flexibility adaptable for wearable Internet of Things devices that can be envisioned as personalized point-of-care devices were produced by electroplating copper on locally carbonized flexible meta-polyaramid (Nomex) sheets using laser radiation. Freestanding films were annealed in nitrogen and nitrogen/air working environments, leading to the formation of Cu microspheroids and CuO urchins dispersed on the substrate film. The aggregation mechanism, crystallographic properties, surface chemistry, and electrochemical properties of the films were studied using scanning electron microscopy, X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. Cu microspheroids and CuO urchins attained activity for glucose detection and showed improvement of amperometric sensitivity to 0.25 and 0.32 mA cm$^{���2}$ mM$^{���1}$, respectively. The CuO urchin film retained its chemical composition after amperometric testing, and, by rinsing, allowed multiple repetitions with reproducible results. This study opens the possibility for the fabrication of durable composite biosensors with tailored shape, capable of implementation in flexible carriers, and microfluidic systems.

Functionalization of metal-organic frameworks (MOFs) is critical in exploring their structural and chemical diversity for numerous potential applications. Herein, we report multiple approaches for the tandem postsynthetic modification (PSM) of various MOFs derived from Zr(IV), Al(III), and Zn(II). Our current work is based on our efforts to develop a wide range of MOF platforms with a dynamic functional nature that can be chemically switched via thermally triggered reversible Diels-Alder (DA) and hetero-Diels-Alder (HDA) ligations. Furan-tagged MOFs (furan-UiO-66-Zr) were conjugated with maleimide groups bearing dienophiles to prepare MOFs with a chemically switchable nature. As HDA pairs, phosphoryl dithioester-based moieties and cyclopentadiene (Cp)-grafted MOF (Cp-MIL-53-Al) were utilized to demonstrate the cleavage and rebonding of the linkages as a function of temperature. In addition to these strategies, the Michael addition reaction was also applied for the tandem PSM of IRMOF-3-Zn. Maleimide groups were postsynthetically introduced in the MOF lattice, which were further ligated with cysteine-based biomolecules via the thiol-maleimide Michael addition reaction. On the basis of the versatility of the herein presented chemistry, we expect that these approaches will help in designing a variety of sophisticated functional MOF materials addressing diverse applications.

Kinetic study was applied for sodium bentonite (Na-B) and hexadecylpyridinium bentonite (HDP-B) under different amounts, namely 50% (50HDP-B), 100% (100HDP-B), and 200% (200HDP-B) with respect to cation exchange capacity (CEC). Pseudo first-order and pseudo second-order kinetic models were performed to optimize the sorption of Congo red (CR) dye from aqueous solution. The experimental data fit the pseudo second order kinetic model well. The sorption capacity (qe) of CR dye by the organo-bentonites at equilibrium was 36.0 mg g−1 (72.1%) for 50HDP-B, 48.05 mg g−1 (96.1%) for 100HDP-B, and 49.2 mg g−1 (98.4%) for 200HDP-B. These results were considerably higher than that found by Na-B. Response surface methodology with three-variable, three-level Box–Behnken design was applied for 100HDP-B to describe the removal of CR dye. The effects of three variables, namely temperature, adsorbent dosage, and initial dye concentration, were studied. Predicted values of adsorption efficiency were found to be in good agreement with the obtained experimental values (R2 = 0.97). A second-order polynomial model successfully described the effects of independent variables on the CR dye removal. At the optimized condition, the toxic azo dye could be quantitatively removed from aqueous solution. The results of the present study suggest that the organo-bentonite can be used as an efficient sorbent for dye removal from aqueous solution.

Metal–organic frameworks (MOFs), have emerged as ideal class of materials for the identification of structure–property relationships and for the targeted design of multifunctional materials for diverse applications. While the powder form is most common, for the integration of MOFs into devices, typically thin films of surface anchored MOFs (SURMOFs), are required. Although the quality of SURMOFs emerging from layer-by-layer approaches is impressive, previous works revealed that the optimum growth conditions are very different between different types of MOFs and different substrates. Furthermore, the choice of appropriate synthesis conditions (e.g., solvents, modulators, concentrations, immersion times) is crucial for the growth process and needs to be adjusted for different substrates. Machine learning (ML) approaches show great promise for multi-parameter optimization problems such as the above discussed growth conditions for SURMOF on a particular substrate. Here, this work presents an ML-based approach allowing to quickly identify optimized growth conditions for HKUST-I SURMOFs with high crystallinity and uniform orientation. This process can subsequently be used to optimize growth on other types of substrates. In addition, an analysis of the results allows to gain further insights into the factors governing the growth of MOF thin films.

For the first time, a procedure has been established for the growth of surface-anchored metal–organic framework (SURMOF) copper(II) benzene-1,4-dicarboxylate (Cu-BDC) thin films of thickness control with single molecule accuracy. For this, we exploit the novel method solution atomic layer deposition (sALD). The sALD growth rate has been determined at 4.5 Å per cycle. The compact and dense SURMOF films grown at room temperature by sALD possess a vastly superior film thickness uniformity than those deposited by conventional solution-based techniques, such as dipping and spraying while featuring clear crystallinity from 100 nm thickness. The highly controlled layer-by-layer growth mechanism of sALD proves crucial to prevent unwanted side reactions such as Ostwald ripening or detrimental island growth, ensuring continuous Cu-BDC film coverage. This successful demonstration of sALD-grown compact continuous Cu-BDC SURMOF films is a paradigm change and provides a key advancement enabling a multitude of applications that require continuous and ultrathin coatings while maintaining tight film thickness specifications, which were previously unattainable with conventional solution-based growth methods.

SUMMARY Ferrimagnetic, monoclinic 4C pyrrhotite (Fe7S8) is the only iron sulphide with high relevance for palaeomagnetism and rock magnetism that can be identified in rock materials by its characteristic low-temperature anomaly. Despite its relevance in natural magnetism and the many magnetic studies over the last decades, the physics and the crystallography behind this anomaly, also denoted Besnus transition, is a matter of debate. In this study, we analyse the static and dynamic magnetization associated with the Besnus transition in conjunction with low-temperature structural data of 4C pyrrhotite reported in the literature. The correlation between the Fe–Fe bonds causing spin-orbit coupling and the dynamic magnetic properties show that the magnetic characteristics of the Besnus transition stem from the interaction of two magnetocrystalline anisotropy systems triggered by thermally induced structural changes on an atomic level in monoclinic 4C pyrrhotite. This refutes the widespread view that the Besnus transition is caused by a crystallographic change from monoclinic to triclinic.

The monosulfides of the pyrrhotite omission series (Fe1xS; 0 < x 0:125) are important remanence carriers for paleomagnetic reconstruction of the Earth’s crust and extraterrestrial materials. The ferrimagnetic Fe7S8 polytypes are the endmembers, and their stacking modulations of full and vacant layers generate different magnetic anisotropy properties due to the cation-vacancy configurations. In this study, intergrown long-range ordered polytypes with four- and threefold modulation, i.e., 4C and 3C pyrrhotite, were prepared in a diffusion-driven process by quenching of a natural pyrrhotite crystal with randomized vacancies. In addition, a third constituent with coherence lengths of a few nanometers, denoted 3C , was found that exhibits spin-glass behavior at about 10 K due to local magnetic anisotropies arising from vacancy-density variations. The concomitant occurrence of this nano-scale constituent with spin disorder and the long-range ordered polytypes indicate competitive diffusion-driven processes during Fe7S8 formation. Such information provides insight into the provenance and genesis of ferrimagnetic pyrrhotite in Earth and extraterrestrial systems and in a broader sense into vacancy-induced materials., Applied Physics Letters, 121 (15), ISSN:0003-6951, ISSN:1077-3118

This work establishes carbon nanofibre-mediated patterning of metal oxide nanostructures, through the combination of electrospinning and vapor-phase transport growth. Electrospinning of a suitable precursor with subsequent carbonization results in the patterning of catalyst gold nanoparticles embedded within carbon nanofibres. During vapor-phase transport growth, these nanofibres allow preferential growth of one-dimensional metal oxide nanostructures, which grow radially outward from the nanofibril axis, yielding a hairy caterpillar-like morphology. The synthesis of metal oxide caterpillars is demonstrated using zinc oxide, indium oxide, and tin oxide. Source and substrate temperatures play the most crucial role in determining the morphology of the metal oxide caterpillars, whereas the distribution of the nanofibres also has a significant impact on the overall morphology. Introducing the current methodology with near-field electrospinning further facilitates user-defined custom patterning of metal oxide caterpillar-like structures.

Integration of porphyrin based metal–organic frameworks (PP-MOFs) on a solid surface has emerged as a key advancement in terms of exploring their promising applications. However, a great challenge remains unmet when it comes to successfully fabricating a PP-MOF film with crystallinity, controllable orientation, adjustable morphology and thickness, all sustained in one. Herein, for the first time, vapor-assisted conversion (VAC) was developed as a facile and versatile technique to fabricate functional PP-MOF films on various substrates related to different application requirements. To understand the nucleation and growth mechanism, a number of fabrication methods were leveraged to prepare the PP-MOF films, thanks to an assortment of PP-MOFs varying from two-dimensional (2D) to three-dimensional (3D) scaffolds. The studies show that PP-MOF films are likely to display different nucleation and growth processes following different deposition approaches. This study demonstrates the pros and cons of different methods in the fabrication of functional PP-MOF films, potentially offering critical tools and reference points for the preparation of next-generation functional MOF thin films in general.

ISSN:1525-2027

The dispersion of anatase TiO2 on diatomic material was a prospective route to avoid agglomerates of these particles. In this work, the TiO2/diatomite composites were prepared using a solvothermal process and a non-hydrolytic sol-gel method at low temperature on the raw (TDB) and the purified (TDS) diatomite. The synthesized samples were characterized utilizing various techniques. These given that TiO2 anatase was impregnated well on the surface of diatomite, and the immobilization of these particles tends to increase the thermal stability of the composite as compared to the raw diatomite. In addition, the photodegradation of crystal violet (CV) in solution was in the direction of TDB > TDS > TiO2. The 99.996% of CV can be degraded in 210 min of irradiation time at pH 10. These results revealed that the immobilization of titanium on diatomite improves the photocatalytic degradation by reducing the crystallite size of anatase TiO2.

The potential of metal–organic frameworks (MOFs) for applications in optoelectronics results from a unique combination of interesting photophysical properties and straightforward tunability of organic and inorganic units. Here, it is demonstrated that using MOF approach chromophores can be assembled into well‐ordered 1D arrays using metal‐oxo strands as lead structure, and the resulting porphyrinic rows exhibit unique photophysical properties and allow the realization of highly sensitive photodetectors. A porphyrinic MOF thin film, In‐TCPP surface‐coordinated MOF thin films with [021] orientation is fabricated using a layer‐by‐layer method, from In(NO3)3 and TCPP (5,10,15,20‐(4‐carboxyphenyl)porphyrin). Detailed experimental and theoretical analysis reveals that the assembly yields a structure where In‐oxo strands running parallel to the substrate fix the chromophoric linkers to yield 1D arrays of porphyrins. The frontier orbitals of this highly anisotropic arrangement are localized in these columnar arrangements of porphyrins and result in high photoactivity, which is exploited to fabricate a photodetector with record (as compared to other organic materials) responsivity in visible regime of 7.28 × 1014 Jones and short rise/fall times (0.07/0.04 s). This oriented MOF thin film‐based high‐sensitive photodetector provides a new avenue to use inorganic, stable lead structures to assemble organic semiconductors into regular arrays, thus creating a huge potential for the fabrication of optoelectronic devices., Highly photoactive, porphyrinic metal–organic framework (MOF) thin films are grown on substrates using layer‐by‐layer process. The unusual architecture of this particular MOF consists of In‐oxo chains acting as lead structure to obtain highly ordered 1D arrays of porphyrins. The MOF thin film is successfully integrated in a visible light photodetector with record sensitivity, 7.28 × 1014 Jones.

The use of fiber reinforced plastics (FRPs) has significant potential to reduce the weight of components. As regards the sustainability of these components, thermoplastic matrices offer more potential for recycling than thermoset ones. A possible manufacturing process for the production of thermoplastic FRPs is thermoplastic resin transfer molding (T-RTM). In this very moisture-sensitive process, ε-caprolactam in addition to an activator and catalyst polymerizes anionically to polyamide 6 (aPA6). The anionic polymerization of aPA6 is slowed down or even completely blocked by the presence of water. This study analyses the sorption behavior of the matrix, fiber, binder and core materials for the production of anionic polyamide 6 composites, which are processed in the thermoplastic RTM process. Water vapor sorption measurements are used to determine the adsorption and desorption behavior of the materials. The maximum moisture loading of the materials provides information about the water adsorption capacity of the material. This knowledge is crucial for correct handling of the materials to achieve a fast process and good properties of the final product.

The demand for different materials in the field of semiconductors has been driving a strong research during the past decades. Few unique materials have been developed, and with additional modificat...

Magnetic stability of iron mineral phases is a key for their use as paleomagnetic information carrier and their applications in nanotechnology, and it critically depends on the size of the particles and their texture. Ferrimagnetic greigite (Fe3S4) in nature and synthesized in the laboratory forms almost exclusively polycrystalline particles. Textural effects of inter-grown, nano-sized crystallites on the macroscopic magnetization remain unresolved because their experimental detection is challenging. Here, we use ferromagnetic resonance (FMR) spectroscopy and static magnetization measurements in concert with micromagnetic simulations to detect and explain textural effects on the magnetic stability in synthetic, polycrystalline greigite flakes. We demonstrate that these effects stem from inter-grown crystallites with mean coherence length (MCL) of about 20 nm in single-domain magnetic state, which generate modifiable coherent magnetization volume (CMV) configurations in the flakes. At room temperature, the instability of the CVM configuration is exhibited by the angular dependence of the FMR spectra in fields of less than 100 mT and its reset by stronger fields. This finding highlights the magnetic manipulation of polycrystalline greigite, which is a novel trait to detect this mineral phase in Earth systems and to assess its fidelity as paleomagnetic information carrier. Additionally, our magneto-spectroscopic approach to analyse instable CMV opens the door for a new more rigorous magnetic assessment and interpretation of polycrystalline nano-materials., Scientific Reports, 11 (1), ISSN:2045-2322

Volcanic ash (VA) from explosive eruptions contributes to aerosol loadings in the atmosphere. Aside from the negative impact of VA on air quality and aviation, these particles can alter the optical and microphysical properties of clouds by triggering ice formation, thereby influencing precipitation and climate. Depending on the volcano and eruption style, VA displays a wide range of different physical, chemical, and mineralogical properties. Here, we present a unique data set on the ice nucleation activity of 15 VA samples obtained from different volcanoes worldwide. The ice nucleation activities of these samples were studied in the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud simulation chamber as well as with the Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology (INSEKT). All VA particles nucleated ice in the immersion freezing mode from 263 to 238K with ice nucleation active site (INAS) densities ranging from ∼105 to 1011 m−2, respectively. The variabilities observed among the VA samples, at any given temperature, range over 3.5 orders of magnitude. The ice‐nucleating abilities of VA samples correlate to varying degrees with their bulk pyroxene and plagioclase contents as a function of temperature. We combined our new data set with existing literature data to develop an improved ice nucleation parameterization for natural VA in the immersion freezing mode. This should be useful for modeling the impact of VA on clouds., Plain Language Summary: Volcanic ash particles, which are generated during volcanic eruptions, can initiate ice formation in clouds. The clouds formed by these volcanic ash particles can influence precipitation, and in turn, weather and climate. In our study, we investigated the ability with which volcanic ash particles form ice in clouds. We performed our study in a state‐of‐the‐art aerosol and cloud simulation chamber and on a cold‐stage instrument. The findings show that volcanic ash particles can form ice as effectively as mineral dust particles or their components. These results will help scientists to have a better understanding of the impact of volcanic ash particles on clouds., Key Points: The ice‐nucleating ability of natural volcanic ash particles in the immersion freezing mode can vary by 3.5 orders of magnitude. Ice‐nucleating properties of volcanic ash particles correlate to varying degrees with their pyroxene and plagioclase contents. The temperature‐dependent immersion freezing ability of volcanic ash is approximated with an exponential fit line., Alexander von Humboldt‐Stiftung (Humboldt‐Stiftung) http://dx.doi.org/10.13039/100005156, Marie Skłodowska‐Curie Actions, ERC 2018 ADG, Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659, Helmholtz Association of German Research Centres, EUROCHAMP 2020 Infrastructure Activity

1-Hexyne monomers were potentiostatically electropolymerized upon confinement in 1D channels of a surface-mounted metal-organic framework Cu(BDC) (SURMOF-2). A layer-by-layer deposition method allowed for SURMOF depostition on substrates with prepatterned electrodes, making it possible to characterize electrical conductivity in situ, i.e., without having to delaminate the conductive polymer thin film. Successful polymerization was evidenced by mass spectroscopy, and the electrical measurements demonstrated an increase of the electrical conductivity of the MOF material by 8 orders of magnitude. Extensive DFT calculations revealed that the final conductivity is limited by electron hopping between the conductive oligomers.

Hysteresis in the sorption equilibrium influences the production process of many multicomponent material systems. Electrodes for Li-ion batteries consist of several materials, some of which exhibit hysteresis in their sorption equilibrium with water. The moisture content adsorbed and absorbed in the electrodes of the Li-ion battery turned out to be an issue for its electrochemical performance and is reduced in the post-drying process. During this process, hysteresis in the sorption equilibrium needs to be overcome in order to achieve a low residual moisture content of the electrode. Modeling the post-drying process requires a description of the sorption equilibria of water in the components of the battery. This paper builds on previous research about the sorption equilibria and examines the hysteresis behavior of typical graphite anodes, with the active material graphite, carbon black as the conductive additive, and sodium carboxymethyl cellulose as well as styrene butadiene rubber as polymeric binders. Moreover, the mechanisms for the occurrence of hysteresis are presented, and how sorption equilibria during drying can be described is shown by applying models from the literature on the materials of battery electrodes. Theoretical deliberations on hysteresis mechanisms are validated, investigating graphite anodes of different material compositions and their materials.

This work deals with the preparation of MAPO-5 zeolite by a hydrothermal method. In order to study the adsorption properties of this zeolite several transition metals (Fe, Co, Ni, Mn and Zn) were incorporated by a direct route. The obtained zeolites were characterized by various physico-chemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, adsorption/desorption of argon, thermogravimetric analysis/differential thermal analysis, scanning electronic microscopy (FEG-ESEM) and Inductively coupled plasma–optical Emission spectrometry (ICP-OES). The prepared zeolites were tested for adsorption of water and xylene isomers (ortho-, para- and meta-xylene). The obtained results showed that the isomorphic substitution of the transition metals in the framework of the zeolite has been achieved with different levels of metals. The isomorphic substitution by zinc showed the best results in terms of the percentage of the incorporated metal, while the substitution by cobalt presented the lowest rate of incorporation in the framework of the zeolite CoAPO-5. The adsorption of water in the vapor state on the zeolite substituted by Ni, Fe and Zn has presented the best adsorption capacity. The adsorption of xylene isomers on MAPO-5 showed different isotherms, confirming that the adsorption behavior differs from one zeolite to another. ZnAPO-5 showed higher adsorption capacity for all xylene isomers with slight selectivity towards meta-xylene.

Migration of atoms in solids during diffusion-dependent reactions is relatively fast and generally not directly recordable in experiments. Here we present an experimental framework that includes fast differential scanning calorimetry to resolve cation-migration paths in crystalline solids using the reversible magneto-structural transition of 4C to 1C pyrrhotite as a testbed. The transition between these two polymorphic Fe7S8 phases at about 600 K is a diffusive process of vacancies, respectively of Fe in octahedral interstitial sites within a hexagonal close-packed lattice of sulfur, and it coincides with the Curie temperature of 4C pyrrhotite. The Fe cations migrate along three kinds of diffusion paths, and their enthalpy contributions to the total reaction enthalpy are taken to define the diffusion patterns in the endothermic reaction and the exothermic back-reaction, respectively. Our experimental findings provide insight into the potential of diffusion patterns to disentangle ordering mechanisms in solids.

The emission of natural dust particles into the atmosphere from the high-latitude/cold regions is fast-becoming more important than previously thought. Due to land use and climate changes, a vast expanse of land surface previously covered by ice is getting exposed; hence, leading to an increase in dust emissions from these regions. Currently, an estimated 500,000 km2 land surface area is contributing up to 100 Tg of dust annually1. Aside from the direct impact of this dust on the air quality and direct solar radiation budget, it can also influence the cloud glaciation processes. Many studies have clearly established that mineral dust aerosol particles are generally good ice-nucleating particles2. However, most of these ice nucleation studies have been conducted on dust from deserts and mid-latitude regions. At present, our understanding of the ice-nucleating abilities of dust from high-latitude regions is highly limited. Here, we report the first comprehensive quantification of ice-nucleating properties of dust obtained from a typical high-latitude region – Iceland. We engaged two laboratory set-ups for this investigation – the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) cloud simulation chamber, and the Ice Nucleation Spectrum of Karlsruhe Institute of Technology (INSEKT). Based on the INAS density calculations which we adopted in quantifying the Icelandic dust ice-nucleating efficiencies, our current results show that dust from Iceland nucleates ice effectively in the range of ~ 103 – 1012 m-2 in the temperature range studied (266 K - 238 K). A preliminary assessment shows that from ~ 250 K its ice-nucleating abilities can compete with that of desert dust and agricultural soil dust. Currently, work is ongoing to understand the role that mineral composition plays in ice nucleation behaviour. Potentially, our new results suggest that the high-latitude dust source could contribute to the INP budget of clouds in the region and may influence precipitation and the climate conditions in high-latitude regions.Bullard, J. E. et al. High-latitude dust in the Earth system. Reviews of Geophysics 54, 447–485 (2016). Hoose, C. & Möhler, O. Heterogeneous ice nucleation on atmospheric aerosols: a review of results from laboratory experiments. Atmos. Chem. Phys. 12, 9817–9854 (2012).

Sodium tantalate, NaTaO3, is one of the best semiconductors for photocatalytic water splitting and CO2 reduction. Doping with metal cations is crucial for enhancing the quantum efficiency of the desired reactions. Nevertheless, details related to the doping of the host metal oxide and activation by guest metal cations are not sufficiently known. The most fundamental question concerns the increase in the quantum efficiency via doping with guest cations that are impurities in the host lattice. In this study, the local environment of Sr cations, which are the typically used guest cations in NaTaO3, was characterized by extended X-ray absorption fine structure spectroscopy. The results reveal the presence of two Sr-O shells in the Sr-doped NaTaO3 photocatalysts. The small shell with an unexpectedly short Sr-O bond length of 1.96 Å corresponds to SrO6 octahedra embedded in the corner-shared network of TaO6 octahedra. The other shell with a Sr-O bond length of 2.60 Å corresponds to SrO12 cuboctahedra with Sr cations at positions previously occupied by Na cations. Rietveld analysis of the X-ray diffraction data confirmed the formation of a NaTaO3-Sr(Sr1/3Ta2/3)O3 solid solution to accommodate the two Sr-O shells in NaTaO3 with no requirement for creating oxygen anion vacancies. Mechanisms for increasing the quantum efficiency via doping with Sr cations are discussed in the context of the revealed environment.

The purpose of this study deals with the use of a new strategy of solidification/stabilization (S/S) process of heavy metals recovered from waste sludge into low-cost nanomaterial frameworks. The new alkaline fusion process applied to waste sludge and raw Bentonite provides a selective recovery metals. The efficiency of the new adopted process in the selectivity and the yield of the metal recovery are compared with the acid leaching process. The obtained results are determined through inductively coupled plasma optical emission spectrometer (ICP-OES) analyses. As results, it is found that the acid leaching process favors the extraction of iron, zinc and copper respectively, whereas the alkaline fusion process leads to a selective extraction in favor of zinc. It is found else that the mass ratio Si/Zn depends on the alkaline fusion period. The structural and textural properties of MCM-41 synthesized depend on the mass ratio Si/Zn. Based on the XRD and N2 sorption, highly ordered hexagonal nanomaterials with uniform pore sizes around 3.8 nm and 3.9 nm, pore volumes ca. 0.7 cm3/g and 0.6 cm3/g and high specific surface areas up to 1100 m2/g and 980 m2/g have been successfully synthesized from (sup I) and (sup II) respectively without any phases such as ZnO, Zn2SiO4, and ZnAl2O4.

An atomic-level understanding of dioxygen activation on metal oxides remains one of the major challenges in heterogeneous catalysis. By performing a thorough surface-science study of all three low-index single-crystal surfaces of ceria, probably the most important redox catalysts, we provide a direct spectroscopic characterization of reactive dioxygen species at defect sites on the reduced ceria (110) and (100) surfaces. Surprisingly, neither of these superoxo and peroxo species was found on ceria (111), the thermodynamically most stable surface of this oxide. Applying density functional theory, we could relate these apparently inconsistent findings to a sub-surface diffusion of O-vacancies on (111) substrates, but not on the less closely packed surfaces. These observations resolve a long standing debate concerning the location of O-vacancies on ceria surfaces and the activation of O2 on ceria powders.

Removal and interaction mechanisms of four different steroid micropollutants, estrone (E1), estradiol (E2), progesterone (P) and testosterone (T) were determined for different types of polymer-based spherical activated carbon (PBSAC). Higher than 90% removal and significantly faster kinetics compared to conventional granular activated carbon (GAC) were observed, while performance was comparable with powdered activated carbon (PAC). No influence of pH in the range 2–12 was determined, while the presence of humic acid (HA) reduced both the removal and the kinetic by up to 20%. PBSAC was characterized in terms of morphology and material properties. The low oxygen content was identified as the main cause for the high performance observed. This was attributed to the enhancement of the hydrophobic effect between PBSAC and hormones and the reduced interactions between PBSAC and water. The ratio of micropollutant size (∼0.8 nm) and average pore size (1–2 nm) proved ideal for both micropollutant adsorption and HA exclusion. The homogenous size, spherical shape and surface smoothness of PBSAC did not influence adsorption negatively and make PBSAC a very promising sorbent for a vast range of applications, in particular for the removal of micropollutants in water treatment applications.

The ability to control the structure and topology of polymer networks, both on macroscopic and molecular levels, is crucial for optimizing their performance. Here we describe a novel type of network polymer, which is synthesized via conversion of a highly ordered metal–organic framework (MOF) template into a polymer gel. The synthesis is performed using light-induced and metal-free thiol–ene click chemistry. The use of light-triggered reactions in combination with photomasks or other photopatterning techniques allows the reaction to be locally confined and thereby structuring the network polymer on a macroscopic level. The potential to vary and exactly adjust the parameters within the polymer network (including exact network topology on the nanometer scale as well as the macroscopic morphology) combined with the ability to further functionalize their surfaces or incorporate guest molecules allows their targeted design for potential applications in catalysis and optoelectronics as well as their use as a no...

International audience; Al-SBA-15 is an interesting mesoporous material having highly ordered nanopores and a large surface area, which is widely employed as catalysts and adsorbents, but relatively few studies on the surfaces properties of this type of materials have been carried out. The purpose of the present work was to advance knowledge on the textural properties of Al-SBA-15 by applying the accurate NLDFT method as well as to gain insight into the surface characterisation and acidic trend of this material. Mesoporous Al-SBA-15 molecular sieves, in three SiO2/Al2O3 ratios: 50, 75 and 100 were accomplished by post-synthesis alumination in aqueous solution of a purely siliceous SBA-15 material. The obtained solids were characterized using powder X-ray diffraction (XRD), X-ray fluorescence (XRF), N-2 adsorption-desorption (BET/DFT), transmission electron microscopy (TEM), water adsorption and zeta potential measurements. The results indicate that Al atoms have been successfully incorporated into the framework of the hexagonal mesoporous SBA-15. The aluminum introduced amount has remarkably affected the surface properties of the SBA-15 solid, indeed microporosity decreased. Furthermore, the esterification test showed that the Al-SBA-15 material exhibit Bronsted acid properties with an interesting activity leading to yields of similar to 90% of biodiesel.

Edible rice paper wrapper is found to be an interesting precursor of a porous and light-weight carbon material. During pyrolysis, material samples show significant differences in length change, displaying typical 20-25% shrinking in the in-plane directions, and strongly expanding (up to 500%) across their out-of-plane direction. This results in a template-free synthesis of a 3D network of cellular carbon material. The out-of-plane expansion also allows for fabrication of 3D shapes of cellular carbon material from the 2D precursor. The rice paper derived carbon material features a hierarchical porosity, resulting in a specific surface area ranging from 6 m

The performance of electrical discharge machining is dependent mainly on the dielectric fluid and process parameters. Significant attention has been drawn to introducing alternative dielectric fluids in order to achieve superior surface integrity and higher productivity. However, there is a challenge in producing more uniform surface layers in the emerging nitriding process by electrical discharges. Thus, this work studies the relationship between process parameters and the features of the layers produced using surface modification by die-sinking electrical discharge machining employing urea [(NH2)2CO] in deionized water as dielectric fluid. The influence of pulse-on time and pulse-off time on the uniformity and thickness of the recast layer, heat-affected zone, and depth of hardened layer was investigated. The experimental work employed annealed AISI H13 tool steel as base material and electrolytic copper as electrode. In order to characterize the samples and investigate the modifications produced by the process, chemical analysis, optical microscopy, scanning electron microscopy, X-ray diffraction, and microhardness measurements were used. The results indicated an evident influence of the process parameters on uniformity and thickness of the layers. The thickest altered metal zone layer obtained was 53.2 ± 5.5 μm when both pulse-on and -off times of 500 μs were used, while the smallest thickness of 31.0 ± 4.6 μm was obtained for both pulse times of 100 μs. The investigated process increased the surface hardness about three times compared with the non-processed AISI H13 steel. This can be attributed to the iron nitrides such as Fe11N found in the samples.

Laser polishing of metals consists of irradiating the part’s surface with a laser beam, thus generating a molten layer that is redistributed and resolidified to create a surface with reduced roughness. However, the process is also characterized by an instantaneously formation of heat-affected zones with consequent microstructural changes that influences the mechanical properties. In order to understand the microstructural evolution during laser polishing of Ti-6Al-4V laser-based powder bed fusion samples, a thermal model is applied in the current study to predict the dimensions of the melted zones and the heat-affected areas. Furthermore, the results obtained through the simulations are discussed and compared to the experimental data, thereby establishing the validity of the process models. Finally, the experimental studies also include the evaluation of the material hardness and residual stresses after laser polishing.

Aluminosilicate (Al-MCM-41) was synthesized via a modified wet-method in a Si/Al atomic ratio of 13.64:1.00 and calcination at 500 °C. The structural as well as the thermal stability were studied by powder X-ray diffractometry (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), Fourier transform infrared (FTIR) analysis and surface area measurements. Al-MCM-41 was confirmed to acquire a mesoporous structure with a high stability against hydrolysis which was attributed to the homogeneous dispersion of Al(III) in the silica framework. The adsorption parameters of the cationic dye methylene blue (MB), on Al-MCM-41 were investigated in aqueous solutions. The adsorption isotherm data showed a notable monolayer adsorption capacity (285 mg g−1) of MB and fitted well the Langmuir adsorption model and the pseudo-second-order kinetics model. The adsorbent was applied successfully for removing 92.0–94.7% of MB from spiked fresh water samples and the initial capacity was recovered by 0.05 mol L−1 HCl or calcination.

A method for the fabrication of flexible electrical circuits on polyaramid substrates is presented based on laser-induced carbonization followed by copper electroplating. Locally carbonized flexible sheets of polyaramid (Nomex), by laser radiation, create rough and highly porous microstructures that show a higher degree of graphitization than thermally carbonized Nomex sheets. The found recipe for laser-induced carbonization creates conductivities of up to ∼45 S cm-1, thereby exceeding that observed for thermally pyrolyzed materials (∼38 S cm-1) and laser carbon derived from Kapton using the same laser wavelength (∼35 S cm-1). The electrical conductivity of the carbonized tracks was further improved by electroplating with copper. To demonstrate the electrical performance, fabricated circuits were tested and improvement of the sheet resistance was determined. Copper films exhibit antimicrobial activity and were used to fabricate customized flexible antibacterial coatings. The integration of laser carbonization and electroplating technologies in a polyaramid substrate points to the development of customized circuit designs for smart textiles operating in high-temperature environments.

Quantifying the impact of complex organic particles on the formation of ice crystals in clouds remains challenging, mostly due to the vast number of different sources ranging from sea spray to agricultural areas. In particular, there are many open questions regarding the ice nucleation properties of organic particles released from terrestrial sources such as decaying plant material. In this work, we present results from laboratory studies investigating the immersion freezing properties of individual organic compounds commonly found in plant tissue and complex organic aerosol particles from vegetated environments. To characterize the ice nucleation properties of plant-related aerosol samples for temperatures between 242 and 267 K, we used the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber and the Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology (INSEKT), which is a droplet freezing assay. Individual plant components (polysaccharides, lignin, soy and rice protein) were mostly less or similarly ice-active compared to microcrystalline cellulose, which has been suggested by recent studies as a proxy for quantifying the primary cloud ice formation caused by particles originating from vegetation. In contrast, samples from ambient sources with a complex organic matter composition (agricultural soils, leaf litter) were either similarly ice-active or up to two orders of magnitude more ice-active than cellulose. Of all individual organic plant components, only carnauba wax (i.e. lipids) showed a similarly high ice nucleation activity as the samples from vegetated environments over a temperature range between 245 and 252 K. Hence, based on our experimental results, we suggest to consider cellulose as being representative for the average ice nucleation activity of plant-derived particles, whereas lignin and plant proteins tend to provide a lower limit. In contrast, complex biological particles may exhibit ice nucleation activities which are up to two orders of magnitude higher than observed for cellulose, making ambient plant-derived particles a potentially important contributor to the population of ice-nucleating particles in the troposphere.

High quality, monolithic UiO‐66‐NH2 thin films on diverse solid substrates have been prepared via a low temperature liquid phase epitaxy method. The achievement of continuous films with low defect densities and great stability against high temperatures and hot water is proven, clearly outperforming other reported types of MOF thin films., The synthesis of high quality, monolithic UiO‐66‐NH2 thin films was successfully explored on various solid substrates via liquid phase epitaxy method. The synthesis delivered continuous films with low defect densities and great stability against high temperatures and hot water.