The synthesis of copper citrate complex supported on acid-activated vermiculite was investigated with a view to preparing an efficient, mild, robust and recyclable catalyst for the Biginelli reaction. The new catalyst was characterized by X-ray fluorescence (XRF), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). Copper citrate supported over activated vermiculite (AAVrm-Cu2) showed good catalytic activity in the synthesis of 3,4-dihydropyrimidinones. The catalyst can be separated easily from the reaction mixture by filtration and retains its catalytic activity for up to five cycles of reaction with no apparent decrease in yield.

Thermoplastic polyurethane (TPU) matrix was reinforced with polyhedral oligomeric silsesquioxane (POSS) and halloysite nanotubes (HNT), both separately and combined. Composite samples were fabricated using a melt-compounding method. Characterization of the composites obtained was performed via tensile and hardness tests, melt-flow index measurements (MFI), abrasion tests, dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM) to investigate the mechanical performance, flow behaviour, tribological characteristics, thermo-mechanical response and morphological properties. The greatest tensile strength value was obtained for the smallest HNT content. Further addition of HNT resulted in agglomerations for both POSS and HNT particles. The shore hardness of TPU was enhanced by filler inclusions. The TPU/POSS composites displayed significant improvement in terms of abrasion resistance compared to TPU at lower loading levels. The DMA study showed that composites containing 0.5% POSS and 1.0% HNT displayed the greatest storage modulus. The glass-transition temperature of TPU shifted to smaller values with the addition of both nanoparticles. The HNT inclusions increased the MFI value of TPU because of their large aspect ratio. Homogeneous mixing of nanoparticles in the TPU matrix was confirmed by a SEM study of the composites. Their dispersion decreased as the concentrations of POSS and HNT increased. An adjuvant effect of POSS with HNT was achieved in their hybrid composites.

To produce an optimized matrix for the in situ crystallization of zeolite Y, a commercial kaolin chemically treated with NaOH solution at 97°C for 24 h and thermally transformed from 750 to 1100°C was studied. The kaolin calcined at 750°C has 20% more reactive tetrahedral aluminium species for the synthesis of zeolite Y than kaolin calcined at 865°C. The kaolin calcined at 1000°C has amorphous silica zones that may be extracted using caustic solution; this increases the surface area by a factor of 16 and generates mesopores ~5 nm in diameter. These structural changes in the calcined and treated kaolins were combined to prepare microspheres of the mesoporous matrix, upon which well-dispersed crystals of zeolite Y crystallized.

Volcanic tuffs are important in determining the stratigraphic age of sedimentary sequences, which is closely related to the tectonic, sedimentological, geomorphological, palaeoclimatic, and palaeo-ecological evolution of the sequences. However, it may be difficult practically to identify tuffs in stratigraphic sections, especially when they are altered after deposition. In this study, a series of petrographic, mineralogical, and geochemical analyses was deployed in the tuff layers cropping out in the Lunpola Basin of the central Tibetan Plateau, which is a crucial site for studying the dynamics and processes of the Cenozoic uplift of the Tibetan Plateau and its environmental impacts. In these pyroclastic layers, authigenic analcime is the main volcanic glass alteration product. The analcime-bearing samples are Na-enriched, in contrast to the K-abundant magmatic rocks in the central Tibetan Plateau. The distribution patterns of the rare earth elements (REEs) of the bulk analcime-bearing samples are similar to those of the magmatic rocks but different from those of the analcime-poor sediments and analogues of well-mixed upper continental material (e.g. the upper continental crust and post-Archaean Australian average shales). The distinct distributions of Na and REEs among analcime-bearing samples, analcime-poor sediments, and volcanic rocks reveal that analcime formed both from alteration of volcanic material and from mixing processes with non-volcanic sediments. It is proposed, therefore, that the discrimination plot of Na2O/Al2O3-(La/Yb)N may be used to distinguish the analcime-related pyroclastic rocks from the basin sedimentary sequence, and thus it may provide a means of discriminating between various volcanic material and of supporting age dating by tephrochronology in the central Tibetan Plateau.

Sepiolite powder was hydrothermally solidified into a cemented, designed to function both in humidity regulation and volatile organic compound (VOC) removal. The solidification process mimicked the cementation of sedimentary rocks. The formation of the calcium aluminium silicate hydrate (C-A-S-H) or Al-tobermorite enhanced the strength (maximum flexural strength >17 MPa) and improved the porosity of the solidified materials. Due to the low temperature of hydrothermal solidification (≤473.15 K), most sepiolite remained in the matrix of the solidified specimens. The cemented sepiolite aggregate shows outstanding humidity-regulating performance (moisture adsorption of 430 g m–2), and the synergistic effects of the residual sepiolite and neoformed Al-tobermorite exerted a positive influence on the humidity regulation performance of the material. Similarly to the behaviour of sepiolite, the solidified material also displayed good formaldehyde-removal capacity (60–68%). The pore dimensions controlled the humidity regulation and formaldehyde removal. The humidity regulation depends on the mesopores, which originate mainly from both the original sepiolite and the neoformed C-A-S-H phases and Al-tobermorite, while the formaldehyde removal depends on the micropores from the original sepiolite in the matrix. As such, the cemented sepiolite aggregate might be hydrothermally synthesized and might be used to improve the comfort and safety of indoor environments for human beings.

Potential secondary influences on titanium distribution should be evaluated when using ash beds as volcanic source indicators and for correlation purposes. In this study, well-correlated altered ash beds in Permian–Triassic boundary (PTB) successions of various facies in South China were investigated to better understand their use in source discrimination and stratigraphic correlation. The ash beds deposited in lacustrine and paludal facies contain significantly more Ti relative to deposits in marine facies. Neoformed anatase grains nanometres to micrometres in size are associated closely with clay minerals, whereas detrital anatase was observed in the remnants of altered ash beds of terrestrial facies. Extraction of the clay fraction of altered ash beds may exclude significantly detrital accessory minerals such as anatase and rutile added during sediment reworking, and the concentrations of immobile elements in the clay fraction may therefore be used to interpret more effectively their source igneous rocks.

The adsorption behaviour of the herbicide clomazone on inorganic and organically modified montmorillonite from the Bogovina deposit in Serbia was investigated. Montmorillonite was modified first with NaCl and then with organic complexes such as hexadecyltrimethylammonium bromide (HDTMA) and phenyltrimethylammonium chloride (PTMA). Changes in the surface properties and morphology of the montmorillonite before and after the modification with various concentrations of organic complexes were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Adsorption of clomazone on all examined samples was investigated using the batch adsorption method. Montmorillonite modified with HDTMA-bromide displayed greater uptake of the clomazone compared to the PTMA-montmorillonite, and both organically modified montmorillonites displayed greater uptake of the herbicide compared to the inorganic montmorillonite. Comparing the Freundlich coefficient and maximum adsorbed clomazone quantity values obtained by Langmuir model, the levels of adsorption of clomazone decreased in the following order: HDTMA-montmorillonite with 1.00 cation-exchange capacity (CEC) saturation > HDTMA-montmorillonite with 0.75 CEC saturation > PTMA-montmorillonite with 1.00 CEC saturation > PTMA-montmorillonite with 0.75 CEC saturation > HDTMA-montmorillonite with 0.50 CEC saturation > HDTMA-montmorillonite with 0.25 CEC saturation > PTMA-montmorillonite with 0.50 CEC saturation > PTMA-montmorillonite with 0.25 CEC saturation > Na-montmorillonite > raw sample. The type and content of an organic cation plays an important role in the behaviour of clomazone in a solid/liquid system. It is concluded that organically modified montmorillonite from Bogovina might be used as an effective adsorbent for clomazone.

This study focuses on the characterization, thermal behaviour and firing properties of clays from Cap Bon Basin, Tunisia. Chemical (inductively coupled plasma atomic emission spectroscopy) and mineralogical (X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy) characterization of the clays was carried out. Physical properties were identified using particle-size distribution and Atterberg limits tests. Differential thermal analysis/thermogravimetry, dilatometry, XRD and FTIR analyses were conducted to assess the thermal behaviour, transformations and crystalline phase development during firing. The clays studied show large proportions of silt and clay fractions. They are rich in SiO2, Al2O3 and Fe2O3 and mostly consist of illite, kaolinite, smectite and minor mixed-layer illite-smectite. Associated minerals are mainly quartz, calcite and feldspar. To monitor the firing properties, three clay mixtures referred to as M1, M2 and M3 were prepared according to the physicochemical and mineralogical characteristics of the raw clays. These were sintered at 900°C, 1000°C and 1100°C and tested for firing shrinkage, flexural strength and water absorption. As a result, various mineralogical transformations occurred at 900–1100°C associated with the crystallization of new phases. The main transformations identified at >1000°C resulted in the formation of anorthite and mullite, causing significant densification of the fired ceramic materials. Sintering at 1100°C increased the densification and thus improved the flexural strength. At this temperature, the sintered ceramic tiles exhibited excellent properties, namely water absorption of 2–3% and flexural strength of 30–41 MPa, indicating that these studied clays might be used as raw materials for the production of stoneware tile ceramics.

Brushite (CaHPO4.2H2O) is an important calcium phosphate encountered in bone tissue engineering and bone cement formulation. There are many studies on the synthesis and characterization of brushite, but full-scale substitution and replacement of Ca by Sr in brushite as a key element in medical and environmental applications has not yet been explored systematically. Therefore, this study aims to evaluate the effects of substitution of Ca by Sr on the microstructural and thermal properties of brushite, including the chemical phases present, crystallization, structural water and phase stability. The chemical phases were determined by means of powder X-ray diffraction. The thermal properties were studied by thermogravimetric analysis. Crystallization and surface morphology were analysed using scanning electron microscopy. Various properties were dependent on the incorporated Sr ions. The replacement percentage of Sr may be divided into two major stages: the first from 0% to 50%; and the second from 50% up to 100%. The (CaxSr1–x)HPO4.nH2O shows that micro-scale crystals of platy brushite formed in the first stage of Sr replacement, from 0% up to 50%. As Sr might inhibit the formation of crystals, crystal nucleation rates were reduced as the Sr percentage increased. An amorphous product formed as a result of 50% Sr replacement. The second stage of Sr replacement with Sr contents >50% yielded a new crystal morphology corresponding mainly to SrHPO4.nH2O. The complete replacement of Ca by Sr transforms the brushite with platy microcrystals into SrHPO4 nanosheets.

The objective of this work was to use air-dried sepiolite granules as an additive in cigarette filter tips to increase the removal yield of tar and nicotine from mainstream smoke. Granules with a mass of 95 mg per cigarette filter and a mean particle size (D) of 0.05–0.41 mm were used to constrain the effects of the mean particle size and mass of sepiolite in the removal process. The granules were sandwiched in common cellulose acetate filter tips. Maximum removal yields of 90% were obtained when D ≤ 0.10 mm. Filters containing granules with a mean size of 0.10 mm and mass variations from 35 to 95 mg were tested, and increasing amounts of sepiolite added led to progressively greater yields of tar and nicotine from 20% to 90%. The sepiolite granules were examined using scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy and X-ray diffraction techniques both before and after smoke experimentation. It is suggested that tar and nicotine were condensed both on the fibre clusters of the sepiolite granules and in the voids between them during the flow of the mainstream smoke.