2.4.1. Characterization of the As-prepared Sample
Characterization of the ionic liquids using 1H NMR and13C NMR were performed on a Bruker High Performance Digital FT – NMR Spectrometer Avance 111 4OOMHz (Micro-analytical unit, NMR Laboratory of Pharmaceutical Collage, Cairo University, Egypt). All spectra were recorded in MeOD and chemical shifts (δ) are reported in ppm relative to tetramethylsilane referenced to the residual solvent peaks. High-resolution transmission electron microscopy (HR-TEM) images were obtained with a (JEM- 2100CX, JEOL, Japan) operated at 200 kV. The HR-TEM specimens were prepared by dispersing a small amount of sample in ethanol, ultrasonicated for 15 min, dropped on a carbon-coated copper grid, dried and photographed. Thermal gravimetric analysis (TGA) was carried out on 0.2 g of each sample which was heated in air flow of 50 cm3/min at heating rate of 5 ᵒC min−1. The TGA curve was recorded during the temperature range of 40–600 ᵒC using a simultaneous TGA – DSC model SDT Q600 apparatus (USA). The BET surface areas for the specimens were measured by N2 adsorption/desorption isotherms at 77 K using Autosorb 1, Quantachrome instrument.