Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied.

Metal-carbon nanocomposites possess attractive physical-chemical properties compared to their macroscopic counterparts. They are important and unique nanosystems with applications including in the future development of nanomaterial enabled sensors, polymer fillers for electromagnetic radiation shields, and catalysts for various chemical reactions. However, synthesis of these nanocomposites typically employs toxic solvents and hazardous precursors, leading to environmental and health concerns. Together with the complexity of the synthetic processes involved, it is clear that a new synthesis route is required. Herein, Cu/C, Ni/C and Co/C nanocomposites were synthesized using a two-step method including mechanochemical treatment of polyethylene glycol and acetates of copper, nickel and cobalt, followed by pyrolysis of the mixtures in an argon flow at 700 °C. Morphological and structural analysis of the synthesized nanocomposites show their core-shell nature with average crystallite sizes of 50 (Cu/C), 18 (Co/C) and 20 nm (Ni/C) respectively. The carbon shell originates from disordered sp² carbon (5.2–17.2 wt.%) with a low graphitization degree. The stability and prolonged resistance of composites to oxidation in air arise from the complete embedding of the metal core into the carbon shell together with the presence of surface oxide layer of metal nanoparticles. This approach demonstrates an environmentally friendly method of mechanochemistry for controllable synthesis of metal-carbon nanocomposites.

Structural (crystallinity), textural (pore volume, V_p, specific surface area, S_BET, pore size distribution, PSD) and adsorption characteristics of bleached flax fibres and cotton fibres have been determined using equilibrium adsorption of nitrogen, water, chlorhexidine diacetate (CHX) and methylene blue (MB), adsorption–desorption kinetics of MB and CHX, X-ray diffraction, infrared spectroscopy, thermogravimetry, differential scanning calorimetry (DSC) and DSC cryoporometry. Air-dry, degassed, wetted (RH ≈ 95%), swollen (24 h in water) and air-dried and heated (120 °C for 1 h) fibres were studied. Flax fibres have higher crystallinity, adsorption capacity (MB, CHX, water), and smaller MB desorption than cotton fibres. Cotton fibres have larger V_p value (nitrogen adsorption) and the S_BET,N2 similar to that of flax. Water vapour adsorption is higher on flax since the adsorbed water volume is V_p,w = 0.19 and 0.14 cm³ g⁻¹ for flax and cotton, respectively, at RH ≈ 95%. Wetted fibres are characterised by V_p,w larger by an order of magnitude than V_p,N2 for degassed samples because of swelling effect. However, nanopores at radius R < 1 nm are practically absent in all samples studied regardless of the characterisation technique. The adsorption of MB and CHX on flax fibres is much larger than that for cotton fibres. The specific surface area determined from MB adsorption is 51 m² g⁻¹ (close to S_BET,w estimated from water adsorption but larger than S_BET,N2) and 8 m² g⁻¹ (much smaller than S_BET,N2 and S_BET,w) for flax and cotton fibres, respectively.