Design of composite maghemite/hematite/carbon aerogel nanostructures with high performance for organic dye removal

Exfoliation of 2D materials by saponin in water: Aerogel adsorption / photodegradation organic dye

The biggest challenge for the paint industry is to clean the contaminated waste dye solution before it released into the water or to reuse it to create new paint and to protect the water from environmental pollution. Here in this work, exfoliating layered transition metal dichalcogenide materials prepare to the exfoliated 2D materials thin sheets in water with the assistance of natural saponin. Then, the three-dimensional (3D) MoS₂-aerogel composite was synthesized by using greenway exfoliated two-dimensional (2D) MoS₂ thin sheets to form MoS₂-aerogel composite. The prepared 3D MoS₂-aerogel composite demonstrates excellent 94% methylene blue (MB) dye adsorption ability over 5 min. Moreover, the adsorbed MB of the MoS₂-aerogel shows ∼80% dye degradation activity in the presence of visible light. Therefore, these synthesized 3D MoS₂-aerogel composite could be an excellent candidate for photocatalytic applications in the future.

Magnetic N-doped carbon aerogel from sodium carboxymethyl cellulose/collagen composite aerogel for dye adsorption and electrochemical supercapacitor

Nitrogen-doped carbon aerogels derived from sodium carboxymethyl cellulose were prepared via a multistep approach involving sol-gel, freeze-drying, carbonization, and KOH activation processes; ferric trichloride and collagen were used as cross-linking agent and nitrogen source, respectively. The carbon aerogels exhibited well-developed porous three-dimensional morphologies, high specific surface areas, and excellent magnetic properties. When applied as electrode material, the CA-N0.5 showed a specific capacitance of 185.3F/g at the current density of 0.5A/g in a 6M KOH electrolyte. The specific capacitance retention was 90.2% after 5000 charge/discharge cycles, indicating excellent cycling stability. In addition, the carbon aerogels showed excellent adsorption capacities of 238.2 and 230.4mg/g for malachite green and methylene blue, respectively. These results suggest that N-doped carbon aerogels may be utilized as electrodes in supercapacitors as well as highly efficient contaminant adsorbents in aqueous solutions.

Dye degradation by green heterogeneous Fenton catalysts prepared in presence of Camellia sinensis

This work describes the synthesis and characterization of supported green iron catalysts, prepared with Camellia sinensis tea extract, and their application in heterogeneous Fenton degradation of pollutant dyes. The influence of the catalyst synthesis conditions in the iron and organic content were investigated by X-ray fluorescence and thermogravimetric analyses. Irregular, chain-like nanoparticles, in the size range of 20-100 nm, capped by polyphenolic natural compounds, were visualized by TEM micrographs. TEM-EDS revealed a high iron content in the nanoparticles as well as a high carbon content all over the catalyst surface, indicating the coverage by the polyphenolic compounds of the tea. X-ray powder diffraction revealed the amorphous nature of the nanoparticles, tentatively ascribed to iron(II)/(III) oxides and oxohydroxides composites. The Fenton degradation of different dyes was successfully accomplished, leading to complete decolourization in less than 3 h of reaction. Influence of hydrogen peroxide concentration, catalyst dosage, pH, temperature and catalyst support, were investigated. The catalysts prepared with black tea over silica furnished the higher iron contents and were the most actives for dye degradation.

Solvent-resistant CTAB-modified polymethylsilsesquioxane aerogels for organic solvent and oil adsorption

In this work, we describe the successful synthesis of super-hydrophobic polymethylsilsesquioxane (PMSQ) aerogels with a porous network by a sol-gel polymerization process using methyltrimethoxysilane (MTMS) reactants with the addition of cetyltrimethylammonium bromide (CTAB) surfactants. The specific surface area, pore size and hydrophobicity of the CTAB-modified PMSQ aerogels were investigated for different amounts of CTAB doping. The specific surface areas of the pristine and CTAB-modified PMSQ aerogels with C/M molar ratios of 0.001, 0.002 and 0.004 were 491, 301, 342 and 298m²/g, respectively. The water contact angles of the CTAB-modified PMSQ aerogels with C/M molar ratios of 0.001, 0.002 and 0.004 were 166.38°, 165.62° and 166.43°, confirming the super-hydrophobicity of the CTAB-modified PMSQ aerogels. Compared to pristine PMSQ aerogels, the as-prepared CTAB-modified PMSQ aerogels exhibit more solvent-resistant properties in ethanol (EtOH) and n-hexane solvents. The as-prepared CTAB-modified PMSQ aerogels were further used for organic solvent and oil adsorption applications. Consequently, the as-prepared CTAB-modified PMSQ aerogels have great potential for organic solvent and oil adsorption in industrial applications.