International audienceThis study is devoted to the physicochemical and mineralogical characterizations of palygorskite from Marrakech High Atlas, Morocco. The raw clay and its Na?-saturated\ 2 lm fraction were characterized using chemical, structural, and thermal analytical techniques. Measurements of specific surface area and porous volume are reported. The clay fraction was found to be made up of 95 %of palygorskite and 5 % of sepiolite. An original feature of this palygorskite is its deficiency in zeolitic H2O. The half-cell structural formula of its dehydrated form was determined on the basis of 21 oxygens to be (Si7.92Al0.08)(Mg2.15Al1.4Fe0.4Ti0.05h1)(Ca0.03 Na0.08K0.04)O21, while the hydrated form could be formulated as (Si7.97Al0.03)(Mg2.17Al1.46Fe0.40Ti0.05)(Ca0.03Na0.07K0,03) O20.18(OH)1.94(OH2)3.8812.43H2O. These formulas showthat the (Al3??Fe3?)/Mg2? ratio is around 0.84, revealing a pronounced dioctahedral character. Further, inside its octahedral sheet, it was determined that the inner M1 sites are occupied by vacancies, whereas the M2 sites are shared between 90 % of trivalent cations (78 % for Al3? and 22 % for Fe3?), 7.5 % of Mg2+, and 2.5 % of Ti4+, all of them linked to 1.94 of structural hydroxyls. The two remaining Mg2+ by half-cell occupy edge M3 sites and are coordinated to 3.88 molecules of OH2. Channels of this palygorskite are deficient in zeolitic H2O since they contain only 2.43 H2O molecules.A correlation was found between these results and the observation of very intense and well-resolved FTIR bands arising from dioctahedral domains (mainly Al2OH, Fe2OH, and AlFeOH) along with very small responses from a trioctahedral domain (Mg3OH). Accordingly, a schematic representation of the composition of the octahedral sheet was proposed. The cation exchange capacity, specific surface area, and total pore volume were also assessed to be ca. 21.2 meq/100 g, 116 m2/g, and 0.458 cm3/g, respectively

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The coronavirus pandemic, which appeared in Wuhan, China, in December 2019, rapidly spread all over the world in only a few weeks. Faster testing techniques requiring less resources are key in managing the pandemic, either to enable larger scale testing or even just provide developing countries with limited resources, particularly in Africa, means to perform tests to manage the crisis. Here, we report an unprecedented, rapid, reagent-free and easy-to-use screening spectroscopic method for the detection of SARS-CoV-2 on RNA extracts. This method, validated on clinical samples collected from 280 patients with quantitative predictive scores on both positive and negative samples, is based on a multivariate analysis of FTIR spectra of RNA extracts. This technique, in agreement with RT-PCR, achieves 97.8% accuracy, 97% sensitivity and 98.3% specificity while reducing the testing time post RNA extraction from hours to minutes. Furthermore, this technique can be used in several laboratories with limited resources.

A B S T R A C TIn a companion paper, it has been demonstrated the remarkably beneficial effect of palygorskite clay (Pal) fibers as support material coupled to appropriate thermal treatments and aging under CO 2 atmosphere in monitoring the phase composition of Ag 2 CO 3 -Pal composite. In this new nanocomposite material, the structure of the functional component Ag 2 CO 3 can be controlled from 100% stable monoclinic (m) to 100% metastable hexagonal β through an adjusted mixture of m-and β-Ag 2 CO 3 . The present study deals with the assessment of the visible photocatalytic properties of these various nanocomposite materials towards the removal of Orange G dye from aqueous solutions. It was found that the Ag 2 CO 3 -Pal nanocomposite in which Ag 2 CO 3 was single-phased and crystallized with the stable monoclinic structure was more active than the one crystallizing entirely with the metastable β-Ag 2 CO 3 structure. Nevertheless, the composite material containing a mixture of both Ag 2 CO 3 phases with a relative content of 32% of β-and 68% of m-phase was found to be the most photoactive compound of the series. This behavior reveals likely a synergetic effect between both phases in the photocatalytic degradation of the dye under visible light.

On the key role of the surface of palygorskite nanofibers in the stabilization of hexagonal metastable β-Ag2CO3 phase in palygorskite-based nanocomposites. (2019) Applied Clay Science, 172. 123-134.

The production of fertilizers has been evolving steadily in the last 300 years. It involves a high number of commodities and reagents that share a large portion of the costs and emissions of greenhouse gases (GHGs), particularly carbon dioxide (CO2). Phosphorus, nitrogen, and potassium fertilizers components represent more than 200 million tonnes of production annually. Given that most of the fertilizer production process is dependent on fossil fuels as fuel and feedstock, the amount of CO2 generated is at least 3 tonnes CO2 per tonne of fertilizer. The introduction, in the future, of less intensive carbon technological components and lower energy-consuming separation and catalytic technologies in the fertilizers industry has the potential to reduce CO2 emissions drastically. In this review, we thoroughly analyze the GHG emissions of the fertilizers industry over time and explore pathways to achieve viable and sustainable decarbonization solutions. In the review, we also aim to explore, whenever information is available, the factors (sources) and the ranges of GHG emissions in the different value chains of fertilizer plants. As a result, an overview of the literature on GHG emissions from synthetic fertilizers (N, P, K) industries will be given. More emphasis is on emissions that stem from the extraction of raw materials to final fertilizer products (energy source, efficiency, and fertilizer type) and transportation of intermediates within different sites of the plants (vehicle type, fuel type, and efficiency). A perspective analysis on possible recommendations for future net-zero carbon emissions and carbon capture technologies is also made.

This study deals with the immobilization of mixtures of two semiconductor oxides Cuo and TiO 2 on fi brous palygorskite clay minerai in order to evaluate their photocatalytic activity for removing Orange G dye as model pollutant from aqueous solutions. The elaboration of CuO-TiO:!Palygorskite nanocomposites was carried out by impregnation with Cu 2+ of before hand synthesized TiO 2 sup ported palygorskite (Pal) followed by air annealing for 5 h at 550 •c. ln the composite materials, different Cuo to Cuo+ TiO 2 molar ratios were used in order to obtain a Cuo content in the range 13-30 mol.%. XRD, SEM and TEM equipped with elemental EDS analysis are concordant for show ing the crystallization of anatase TiO 2 along with Cuo whose average size of nanoparticles (NPs) are in the range 6 to 20 nm as determined by TEM. By increasing the Cuo content the average size of this oxide remains constant at about 1 O nm while that of TiO 2 NPs is slightly decreasing from 8.4 to 5.1 nm. Both oxide NPs were successfully attached on palygorskite fibers where they form Cu0-TiO 2 heterojunctions (grain boundaries like). The Cu0-TiO 2 /Pal supported photocatalyst con taining 23% of Cuo was found to be the most photoactive material but itremained less active than TiO 2 /Palygorskite supported photocatalyst. The photocatalytic activity of the mixed nanocomposites is not readily correlated with only one of their main features as Cuo content or the average crystal lite size of functional oxides indicating that if there are synergistic effects there are also antagonistic effects in particular for high Cuo contents.

Composed of two europium complexes doped in polyvinyl butyral as the host material, a novel photoluminescent ink has been formulated by synthesizing Eu­(FAC)3Phen as a red luminescent down-shifting emitter and employing SrAl2O4:Eu, Dy as a long persistent green phosphor. Both emitters are incorporated to design a photoluminescent ink with binary emission under a single UV excitation wavelength, where a red light is emitted when exposed under 325 nm, subsequently becoming green upon the UV light being switched off. The concept presented here is unequivocally distinct from the classical dual-mode emission, which requires a second extra near-infrared excitation around 980 nm to produce a binary luminescence. This work demonstrates the effortlessness of using one UV excitation for dual-mode visible emission while rendering the counterfeiting of confidential documents more onerous.