2. Experimental 2.1. Catalyst preparation The CuMnOx catalyst was prepared by the co-precipitation method, the aqueous solution manganese acetate (Mn(CH3COO)2.4H2O) and copper (II) nitrate (Cu(NO3)2.2.5H2O) were premixed by stirring for 1 hour. After the proper mixing of the copper nitrate and manganese acetate solution, it was added to the aqueous KMnO4 solution by a burette under the stirring conditions. After dropped completely the copper manganese solution into the precipitant ageing for 2h, then filtered, washing several times with hot deionized water.
Among four types of surfactants, partially hydrolyzed PVA is most frequent used because it gives the smallest microsheres (Jeffrey et al, 1991). The amount of PVA used may affect microparticles properties. Freitas and coworkers have added 1.3% and 8% of PVA into an aqueous solution and found that both lower and higher concentrations of surfactant results in coagulation of the particles. Hence, these authors suggested to use 3% of PVA as it the most optimum concentration. (Freitas and Marchetti,
Nanotechnology is the engineering of functional systems at the molecular scale. The study and building of matter and molecules is involved. This happens at the scale of 0.1 to 100 nanometers. A nanometer is a type of measure and an idea of is its equivalence would be a strand of hair which is 50 000 nanometers in terms of diameter and a nylon fibre which 30 000 nanometers. This should give a clear picture of how small a nanometer is.
The CuO precursors containing Na+-dopant was prepared with 1.0 mole% and 2.0 mole % of sodium nitrate concentration. The resultant solutions was subjected to slow magnetic stirring at 50°C until a uniform light green solutions are formed, indicating the formation of copper hydroxide. 0.2 M of sodium hydroxide
Nanotechnology has many definitions. It is the “understanding and control of matter at dimensions of roughly one to one hundred nanometers, where unique phenomena enable novel applications,” according to the National Nanotechnology Initiative (NNI). The U.S. Environmental Protection Agency (EPA) defines nanotechnology as “research and technology development at the atomic, molecular, or macromolecular levels using a length scale of approximately one to one hundred nanometers in any dimension; the creation and use of structures, devices and systems that have novel properties and functions because of their small size; and the ability to control or manipulate matter on an atomic scale. Scientists have been studying and working with nanoparticles
Introduction Copper, iron and gold were the raw metals that were produced for more than two thousand years. They were the commodities consumed by civilisation, which are pillared upon metallurgy. Metals have took upon a large and significant role during the pre-industrial period through the establishment of trade routes, accumulation of wealth and also knowledge transfer which was implemented through a society known as the ‘Brotherhood’. Objects of iron, gold and copper have substantially been significant toreligious, political, social and economic life. However, in Africa iron has always been the essential metal in all the perspectives of life since the establishment of the metallurgical revolution.
Some bidentate directing groups also used for these heterocyclic syntheses. Chatani et al discovered a nickel catalyzed synthesis of isoquinolones from aromatic amides containing 2-pyridylmethylamine moiety 1.72 by oxidative cycloaddition with alkynes (Scheme 1.23).32 The reaction proceeds via coordination of amide 1.72 to the nicker center in a N,N-fashion and forms a cyclometallated complex. Insertion of alkyne into this ortho-metalated complex, followed by reductive elimination afforded the
As a result, the sources of red sandalwood were dried up. Therefore, the imperial court of Qing dynasty gave explicit instructions to officials in different regions to collect red sandalwoods from folk society. Once finding red sandalwood, it was confiscated and turned in to the imperial court. After hundreds of years of plunder, almost no red sandalwood can be found in folk society. Therefore, red sandalwood had become a material exclusively enjoyed by royal family.