M.A. Hassan

Hafnium pentachloride ionic liquid for isomorphic and postsynthesis of HfKIT-6 mesoporous silica: catalytic performances of Pd/SO4 2−/HfKIT-6

Isomorphic substitution or post-synthesis incorporation of hafnium into KIT-6 mesoporous material has been fabricated for the first time in highly acidic media using triethylamine hafnium pentachloride ionic liquid (TEA-HfCl5) as a novel hafnium precursor ionic liquid (Si/Hf molar ratio of 90). The prepared catalysts were characterized by X-ray diffraction, Fourier transfer infrared (FT-IR), pyridine-FT-IR, N2-adsorption, transmission electron microscopy and the surface acidity was tested by temperature programmed desorption (NH3-TPD) of ammonia. The effect of the nature of hafnium source in the KIT-6 synthesis has been investigated using different hafnium source, viz., triethylamine hafnium pentachloride ionic and hafnium chloride. Triethylamine hafnium pentachloride ionic was found to be the better hafnium source for HfKIT-6 material synthesis and enhanced the amount of hafnium incorporation in the KIT-6 silica walls. ICP-AES studies evidenced that the proportion of Hf4+ increases using triethylamine hafnium pentachloride ionic. The catalytic performance of SO42−/HfKIT-6 was investigated by cracking of 1,3,5-triisopropylbenzene, esterification of acetic acid with n-butanol, while Pd/SO42−/HfKIT-6 was examined by n-C7 isomerization reaction. Our findings indicated that HfKIT-6 prepared by ionic liquid approach offered distinct structural and surface features, particularly in terms of Brønsted and Lewis acid site contents. As compared with SO42−/HfKIT-6 (direct ionic liquid) and SO42−/HfKIT-6 (direct), SO42−/HfKIT-6 prepared by post ionic liquid exhibited higher yield percentage of 1,3,5-triisopropylbenzene cracking and n-butyl acetate yield. Furthermore, Pd/SO42−/HfKIT-6 catalyst prepared by post ionic liquid shows high isomerization activities compared with Pd/SO42−/HfKIT-6 prepared by direct method using TEA-HfCl5 ionic liquid or HfCl4 materials.

Ultrahigh performance of novel energy-efficient capacitive deionization electrodes based on 3D nanotubular composites

Capacitive deionization (CDI) is being progressed as an auspicious ion removal technique from brackish and seawater. Herein, we introduce a novel one-step facile chemical approach to fabricate tubular architectured composite electrodes made of both Titania and Multiwalled carbon nanotubes (TNTs/MWCNTs). The composites have been exploited, for the first time, as electrode materials for capacitive deionization. The composite electrodes were fully characterized via Field Emission Scanning Electron Microscopy (FESEM), Raman spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) techniques, and Nitrogen Sorption. The electrochemical response was investigated by using Cyclic Voltammetry (CV), Galvanostatic Charge and Discharge (GCD), and Potentio-Electrochemical Impedance Spectroscopy (PEIS) measurements. The fabricated composite electrodes containing 5 wt% TiO2 nanotubes showed remarkable specific capacitance, conductivity, reversibility, and durability compared to pristine MWCNTs and other MWCNT-based composite electrodes reported in the literature. The desalination capability of the composite electrode was investigated using batch mode operation. The electrosorption capacity of the composite electrode containing 5 wt% TiO2 nanotubes (13.2 mg g−1) is approximately two fold larger than that of pristine MWCNTs (7.7 mg g−1), indicating an improved desalination efficiency. Therefore, the fabricated TNT/MWCNT composite electrode is a promising candidate for CDI technology.