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Hierarchical porous silicon carbide (SiC) attracts great attention due to its superior chemical resistance, high thermal shock resistance, and excellent thermal stability. The preparation of a porous SiC monolith via a simple sol–gel method is limited by either the high cost of the raw materials or the special time-consuming drying process. Herein, we report an ambient drying sol–gel approach for the synthesis of organic–inorganic hybrid monolithic gels which can be converted into hierarchical porous SiC monoliths upon pyrolysis at 1400 °C. The as-synthesized SiC monoliths possess hierarchical pores with macropores of 4.5 µm and mesopores of 2.0 nm. The porosities, specific surface areas and compressive strengths of the hierarchical porous SiC monoliths are 71.3%, 171.5 m2/g and 7.0 ± 0.8 MPa, respectively.

In this study, the reconstruction peculiarities of sol–gel derived Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides were investigated. The mixed metal oxides (MMO) were synthesized by two different routes. Firstly, the MMO were obtained directly by heating Mg(M)–Al–O precursor gels at 650 °C, 800 °C, and 950 °C. These MMO were reconstructed to the Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides (LDHs) in water at 50 °C for 6 h (pH 10). Secondly, in this study, the MMO were also obtained by heating reconstructed LDHs at the same temperatures. The synthesized materials were characterized using X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). Nitrogen adsorption by the Brunauer, Emmett, and Teller (BET) and Barrett, Joyner, and Halenda (BJH) methods were used to determine the surface area and pore diameter of differently synthesized alkaline earth metal substituted MMO compounds. It was demonstrated for the first time that the microstructure of reconstructed MMO from sol–gel derived LDHs showed a “memory effect”.

Photocatalysts have been widely applied in the degradation of organic compounds using visible and ultraviolet radiation. Different synthesis approaches have been developed and optimized to produce efficient, eco-friendly, and inexpensive materials to photo-treat water samples contaminated with dyes, pigments, pesticides, and other organic pollutants. Over the last two decades magnetic materials have emerged as a potential alternative to facilitate catalyst isolation in heterogeneously catalyzed liquid-phase reactions. In this review, we focus on the discussion of several studies including the main synthesis processes and new protocol modifications for the fabrication of magnetic photocatalysts, and their impact on the catalyst morphology, efficiency, and recycling. Emphasis is given on the discussion of the synthesis strategies over last decade to produce photoactive catalysts including single-phase catalysts, composites, Multifunctional metal–organic framework materials, binary and ternary core–shell materials, and yolk–shell photocatalysts. Highlights A review on magnetic materials for photocatalysis is given. Emphasis is given on sol–gel preparation methods utilized for the fabrication of magnetic photocatalysts. Discussion on different material types of magnetic photocatalysts is presented. Magnetic separation properties and efficiency are discussed based on the material structures.

In the present study, DOPO-based alkoxysilane (DOPO-ETES) and amido alkoxysilane (DOPO-AmdPTES) were synthesized by one-step and without by-products as halogen-free flame retardants. The flame retardants were applied on cotton fabric utilizing sol–gel method and pad-dry-cure finishing process. The flame retardancy, the thermal stability and the combustion ehaviour of treated cotton were evaluated by surface and bottom edge ignition flame test (according to EN ISO 15025), thermogravimetric analysis (TGA) and micro-scale combustion calorimeter (MCC). Unlike CO/DOPO-ETES sample, cotton treated with DOPO-AmdPTES nanosols exhibits self-extinguishing ehaviour with high char residue, an improvement of the LOI value and a significant reduction of the PHRR, HRC and THR compared to pristine cotton. Cotton finished with DOPO-AmdPTES reveals a semi-durability after ten laundering cycles keeping the flame-retardant properties unchanged. According to the results obtained from TGA-FTIR, Py-GC/MS and XPS, the major activity of flame retardant occurs in the condensed phase via catalytic induced char formation as physical barrier along with the activity in the gas phase derived mainly from the dilution effect. The early degradation of CO/DOPO-AmdPTES compared to CO/DOPO-ETES, triggered by the cleavage of the weak bond between P and C=O, as the DFT study indicated, provides the beneficial effect of this flame retardant on the fire resistance of cellulose.

The preparation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-functionalised polysilsesquioxane (Si-DOPO)-coating was described and its flame retardant efficiency for cotton fabric was thoroughly investigated. The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide–vinyltrimethoxysilane (DOPO–VTS) was synthesized and applied to cotton fabrics at different concentrations using a sol–gel process. The structure of the synthesized DOPO–VTS was characterized using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The characteristics of the Si-DOPO coatings formed on the cotton fibres were investigated using X-ray photoelectron spectroscopy, time-of-flight-secondary ion mass spectrometry and scanning electron microscopy. The flame retardant properties of the Si-DOPO-coated cotton samples were evaluated by thermogravimetric analyses, vertical flame spread tests and cone calorimetry analyses. The Si-DOPO coating increased the thermo-oxidative stability of the cotton fibres by increasing the stability of the protective char and inhibited cellulose fibres degradation. The Si-DOPO coating did not decrease the time of flaming combustion but did completely stop the vigorous combustion of the fibres. The results also suggest that the flame retardation by the Si-DOPO coating is due to the quenching of active radicals from the decomposing cellulose and the cellulose phosphorylation by the DOPO component as well as the silicon oxide formation by the silsesquioxane component on the fibre surface. These findings indicate that the flame retardant efficiency of the Si-DOPO coating can be ascribed to the combined activity of phosphorus acting in both gas and condensed phases and silicon acting in the condensed phase.

Raman and IR investigations indicated the presence of reduced graphene oxide (rGO)-like residues on ceria nanoparticles after solvothermal treatment in ethanol. The appearance of such structures is closely related to cerium tert -butoxide as precursor and ethanol as solvothermal solvent. The rGO-like residues improve the catalytic CO oxidation activity. This was also confirmed by introduction of “external” graphene oxide during sol–gel processing, by which the rGO structures and the catalytic activity were enhanced.

Bacterial cellulose (BC) produced from Achrmobacter sp. M15, was used to reduce titanium tetra isopropoxide into titanium dioxide nanoparticles (TiO2NPs) via green process. Addition of titanium dioxide nanoparticles (TiO2NPs) was carried out via sol–gel method utilizing 3-Glycidyloxypropyltrimethoxysilane (GPTMS). Transmission electron microscopy (TEM) was used to characterize the prepared TiO2NPs and their particles size were within a range of 5–10 nm. Cellulose-based fabrics (linen, viscose, cotton and cotton/polyester blend; 50:50) finished with BC/TiO2NPs nanocomposite displayed innovative properties e.g., self-cleaning and superior antimicrobial activities were illustrated. FT-IR, thermal gravimetric analysis (TGA), mechanical properties, scanning electron microscopy (SEM) and EDX were used to characterize fabrics treated with TiO2NPs. Results showed that TiO2NPs prepared using BC had innovative properties in comparison to those of the nanoparticles prepared by sol–gel method.

Fabrics with high flame-retardancy have been extensively applied for numerous applications including textile, garments, automobile industries, pants, shirts, suits bed sheets, and indoor decorations. Coatings consisting of ammonium hexametaphosphate (NH4-HMP), laponite (LAP), and hexadecyltrimethoxysilane were synthesized through sol–gel method; they were then employed on the cotton fabrics to enhance their hydrophobicity and flame retardancy. The influences of LAP concentration on fire-retardancy of the samples were evaluated. The combustion behavior, morphological structures, thermal stability, and hydrophobic properties of the cotton fabrics were studied. Results indicated the excellent flame retardant property of the treated cotton fabrics as they immediately extinguished upon removal of the flame source. The limiting oxygen index of the treated cotton was enhanced to 29% in comparison to that of the pure one (19.5%). The findings also indicated that a higher concentration of LAP is useful for improving flame retardancy of the coated substrate. In addition, the hydrophobicity of the fabric surface was measured by a water contact angle of 138°, while its superoleophilicity was assessed by an oil contact angle of 0°. To separate water–oil mixtures, the as-prepared cotton sample was utilized as operative substances. Overall, in this study a facile technique is provided for preparing cotton fabrics with considerably enhanced flame retardancy and superior self-cleaning features toward different fluids making them suitable as a promising candidate for water–oil separation.

Cu/SiO 2 catalysts were prepared by co-precipitation (CP), hydrothermal (HT), ammonia evaporation (AE), and sol–gel (SG) methods and tested for their performance in the dehydrogenation reaction of secondary butyl alcohol to methyl ethyl ketone. The results showed that the Cu/SiO 2 catalyst prepared by the sol–gel method has the best performance. By BET and H 2 –TPR characterization, it can be found that the catalysts prepared by sol–gel method has the largest specific surface areas and lowest reduction temperatures. Based on the characterization results of XRD, XPS and XAES, it shows that the catalyst prepared by sol–gel method has a better dispersion of copper components and a higher content of Cu 0 species after reduction, which leads to its higher catalytic activity. At a copper loading of 22.96% (w%), the conversion of secondary butyl alcohol was up to 99.0% and the selectivity of methyl ethyl ketone was up to 99.8% by using the Cu/SiO 2 catalysts prepared by sol–gel (SG) methods. Graphical Abstract

In this paper, we report on the design of multifunctional cotton fabric with high hydrophobic, water-repellent, water-oil separation, and self-cleaning properties by the sol-gel method using ionic liquids. To do so, sols containing 1-methylimidazolium chloride Propyltriethoxysilane [MCPTS] and 1-pyridinium chloride Propyltriethoxysilane [PCPTS] salts were synthesized and deposited on the surface of the cellulose substrate by the pad-dry-cure process. Finally, the treated fabrics were impregnated in diluted solutions of hexafluorophosphoric acid (HPF6), bis(trifluoromethane) sulfonamide lithium (Li (CF3SO2) 2 N), sodium tetrafluoroborate (NaBF4), and sodium acetate (NaCH3CO2) to achieve the metathesis reaction. The surface morphology of the as-prepared cotton fabric was characterized by the Scanning electron microscope. It shows the presence of a very thin layer of coating on the cotton fiber surface. The Fourier Transform InfraRed (FT-IR) and Energy Dispersive Spectroscopy (EDS) spectrum were exploited in order to characterize the chemical composition of the treated and untreated fabrics. The results showed that the functionalized cotton fabrics by the sol-gel method using ionic liquids exhibited high hydrophobic, excellent water-repellent, and self-cleaning properties. Furthermore, the coated cotton fabric is able to separate a series of oil-water mixtures, which makes it potentially useful in practical and industrial applications.