Ionothermal Carbonization of Sugarcane Bagasse in 1-Alkyl-3-methylimidazolium Ionic Liquids: Insights into the Role of the Chloroferrate Anion

We report the ionothermal carbonization (ITC) of lignocellulosic biomass in imidazolium tetrachloroferrate ionic liquids (ILs) as an advantageous approach for the preparation of nanostructured carbonaceous materials, namely, ionochars. In a previous study, we investigated the role of the imidazolium cation and demonstrated the possibility of controlling both the textural and morphological properties of ionochars by cation engineering. Although essential for providing intermediate Lewis acidity and relatively high thermal stability, the role of the chloroferrate anion is still open to debate. Herein, we investigated the ITC of sugarcane bagasse and its main component, cellulose, in 1-alkyl-3-methylimidazolium ILs with different chloroferrate anions. We identified anionic speciation and its impact on the properties of the IL by Raman spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The obtained ionochars were characterized by gas physisorption, electron microscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and 13C solid-state CP-MAS NMR spectroscopy. We show that the anionic species have a predominant impact on the textural and morphological properties of the ionochars.

Ultrasound-assisted bottom-up synthesis of Ni-graphene hybrid composites and their excellent rhodamine B removal properties

In this paper, a facile one-pot bottom-up approach has been developed for the rapid preparation (≤5 min) of graphene nanostructures and Ni-graphene hybrid composites. Under the aid of ultrasonic irradiation, the graphene nanostructures were prepared via reducing hexachloro-benzene(C₆Cl₆) with sodium (Na) in non-polar organic solvent n-tetradecane (C₁₄H₃₀). On the basis of this route, the Ni-graphene hybrid composites were easily synthesized by adding Ni nanoparticles (NPs) into reaction system. The whole reaction was carried out at low temperature (100-120 °C) and in air atmosphere. Despite the absence of nitrogen protection, the result from surface analysis still shows a relatively high C/O ratio (10:1). The effect of the Ni NPs content and size on the specific surface area (SSA) of the products is also investigated. The synthesized samples exhibit large SSA, which is significantly affected by the Ni NPs content rather than their size. The adsorption performances of the samples are evaluated for the removal of organic dyes such as rhodamine B (RhB) from aqueous solutions. The testing results show great adsorption capacity (q_max = 963.04 mg g^-1), rapid adsorption rate (~99.88%, 2 min), high adsorption efficiency (>99.7%) and good chemical stability in a wide pH range (3-13), high salt tolerance (>80 mg mL^-1), and good recyclability (>99.5%, 20 cycles).

Uniform cobalt nanoparticles embedded in hexagonal mesoporous nanoplates as a magnetically separable, recyclable adsorbent

Novel hexagonal nanoplates (NPLs) comprised of mesoporous carbon containing imbedded magnetic Co nanoparticles (CoAl2O4 phase) are prepared through direct carbonization of polydopamine (PDA)-coated CoAl layered double hydroxide (LDH). A uniform PDA coating initially covers the surface of LDH by dopamine self-polymerization under mild conditions. Well-dispersed Co nanoparticles are formed in the NPLs by the partial reduction of cobalt from Co2+ to Co0 with surface carbon during the heat treatment process. The surface morphology and specific surface area of the as-prepared NPLs can be tailored by adjusting the initial dopamine concentration and carbonization temperature. The mesoporous NPLs exhibit excellent sorption of rhodamine B (RhB) dye and fast magnetic separation in aqueous solution. Over 95% of RhB can be adsorbed within 2 min and the adsorption reaches equilibrium after about 30 min. The maximum adsorption capacity approaches 172.41 mg/g. After regeneration, this adsorbent can be recycled easily by magnetic separation and still possess good adsorption capacity for RhB removal, even after five cycles.

Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap

Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism.

Ionothermal synthesis of magnetically-retrievable mesoporous carbons from alkyne-appended ionic liquids and demonstration of their use in selective dye removal

Tailored metal-containing ionic liquids generate porous carbon suitable for selective dye sorption and Fenton chemistry by thermal cyclotrimerization of terminal alkynes.

Adsorption behavior of magnetic amino-functionalized metal–organic framework for cationic and anionic dyes from aqueous solution

The mechanisms of interactions such as electrostatic interaction, hydrogen bonding, and π–π stacking interaction were discussed for the adsorption of cationic and anionic dyes onto magnetic NH₂-MIL-101(Al).

Facile method for the synthesis of Fe3O4@HCP core–shell porous magnetic microspheres for fast separation of organic dyes from aqueous solution

A novel type of porous magnetic microsphere (Fe3O4@HCP) was firstly synthesized and possesses a high Brunauer–Emmett–Teller specific surface area and excellent adsorption capacity for organic dyes.

From metal–organic frameworks to magnetic nanostructured porous carbon composites: towards highly efficient dye removal and degradation

A magnetic nanostructured porous carbon material (γ-Fe₂O₃/C) was easily synthesized using a microwave-enhanced high-temperature ionothermal method with an iron terephthalate metal–organic framework-MIL-53(Fe), as a template.

Synthesis, structure and magnetic properties of graphite carbon encapsulated Fe3C nanoparticles for applications as adsorbents

This paper reports the synthesis of graphite carbon encapsulated Fe₃C nanoparticles (Fe₃C/GC NPs).