Copper oxide alumina composite via template assisted sol–gel method for ammonium perchlorate decomposition

Facile mass preparation and characterization of Al/copper ferrites metastable intermolecular energetic nanocomposites

In the present work, a novel Al/copper ferrites metastable intermolecular energetic nanocomposite was prepared by a simple and mild sol-gel method followed by low temperature calcination, and characterized by various analytical techniques. The X-ray diffraction (XRD) analysis suggests that the products contain crystal forms of aluminum and spinel-type ferrite crystal forms which are CuFe2O4 with many crystal defects. The scanning electron microscopy (SEM) and nitrogen adsorption-desorption analyses reveal that the prepared Al/copper ferrites are mesoporous structures with large specific surface areas of up to 184.47 m2 g-1 and further reveal the pore construction of this material. Its crystal defects and large specific surface area provide the possibility for its excellent catalytic performance. Al/copper ferrites have 45% better exothermic properties with higher energy output efficiency, faster burning rate, and higher reactivity than traditional Al/Fe2O3 prepared by the same method. Due to the synergistic catalytic effect of Cu-Fe oxides, Al/copper ferrites have a better catalytic effect on AP thermal decomposition and can reduce the HTD peak temperature of AP 33% more than Al/Fe2O3. The catalytic mechanism of Al/copper ferrites for the thermal decomposition of AP is obtained based on the electron transfer theories, synergistic catalytic mechanism, and the porous structure of Al/copper ferrites. Due to the mild reaction conditions and low calcination temperature, dozens of grams of product can be safely obtained at one time with low cost and easily available raw materials to meet the requirements of propellant up to several kilograms or other industrial applications.

Cytotoxic aquatic pollutants and their removal by nanocomposite-based sorbents

Water is an extremely essential compound for human life and, hence, accessing drinking water is very important all over the world. Nowadays, due to the urbanization and industrialization, several noxious pollutants are discharged into water. Water pollution by various cytotoxic contaminants, e.g. heavy metal ions, drugs, pesticides, dyes, residues a drastic public health issue for human beings; hence, this topic has been receiving much attention for the specific approaches and technologies to remove hazardous contaminants from water and wastewater. In the current review, the cytotoxicity of different sorts of aquatic pollutants for mammalian is presented. In addition, we will overview the recent advances in various nanocomposite-based adsorbents and different approaches of pollutants removal from water/wastewater with several examples to provide a backdrop for future research.

Improved catalytic activity on the thermal decomposition of ammonium perchlorate and efficient adsorption of uranium using a novel ultra-low density Al2O3-based aerogels

The ultra-low density AlCl₃-chitosan composite aerogel was prepared via a novel solution-freeze-drying technology. Then, the AlCl₃-chitosan aerogel was carbonized or calcined to remove the chitosan template, yielding ultra-low density Al₂O₃-based aerogels with good formation ability. The density of Al₂O₃-based aerogels were about 9 mg/cm³ via this method. Moreover, the Al₂O₃-based aerogel obtained from the calcination of AlCl₃-chitosan aerogel copied the open networks of thin flakes layered structure of chitosan template. The as-prepared Al₂O₃ aerogel had a low thermal conductivity of about 0.039 W/m K after high temperature treatment at 1000 °C, demonstrating its good thermal insulation property. The results of TG/DSC showed that the Al₂O₃-(0.2 wt% Pt) catalysts could decrease decomposition temperature of ammonium perchlorate (AP) by 51.1 °C and the exothermic heat was increased from 133.2 J/g to 1552.7 J/g. The maximum adsorption amounts for U(VI) of Al₂O₃ aerogel reached 769.9 mg/g, which was about 2 times higher than that of Al₂O₃ with other forms. Accordingly, the Al₂O₃ aerogel with thin flakes layered structure and ultra-low density possessed great potential application in thermal insulation, adsorption and catalyst supports. Meanwhile, the solution-freeze-drying technology is simple and easy to control, providing a new strategy for the preparation of ultra-low density metal oxide aerogels.