In the 1930s, the term photocatalysis was introduced as a new branch of catalysis [1]. Among photocatalytic applications, photocatalytic oxidation and the reduction of organic compounds in water, have become important and have received considerable attention during the last few years [1, 2]. Owing to its excellent catalytic and oxidative properties; titanium dioxide, TiO2, has been frequently employed to degrade most kinds of organic pollutants. Including detergents, dyes, pesticides and herbicides under UV-light irradiation in order to transform them in water, carbon dioxide and some simple mineral acids [3-6]. However, titanium dioxide was used also for other catalytic applications [7, 8]. Among the three common phases of crystalline TiO2, it is widely known that anatase (band gap = 3.2 eV, absorption ≤385 nm) is the most photocatalytically active. Therefore, only a small fraction (~ 5%) of the solar energy can be utilized in practical application [9,10]. Moreover, a low rate of electron transfer to oxygen and a high rate of recombination between excited electron/hole pairs lead to a low quantum yield rate and also a limited photooxidation rate [11,12]. Modification of TiO2 is thus, an active and important field of research. Efforts have been made using chemical or physical methods to enhance the photocatalytic activity of TiO2 through modification with different metal groups such as alkaline metals [13], earth alkaline metals [14], transition metals [15], rare earth metals [16], and noble metals [17], but with varying degree of results.
Transition metal doping have been widely used to extend TiO2’s light absorption in the visible-light region. In particular, tungsten (W) was reported as the best for the photodegradation under ...
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..., we have successfully prepared new W doped TiO2 photocatalysts by the sol-gel method. The new photocatalysts are characterized by different techniques such as DRS, BET, DRX, SEM, and TEM. Photocatalytic experiments are carried out using the CR as a photodegratable organic compound. The obtained results show the formation of nanoparticles with an average size of 10 nm. Moreover, the new photocatalysts have high surface areas and their light absorption extends to the visible region which can promote their photocatalytic activity. Thus it is found that W0.5-TiO2 calcined at 350°C for 2h shows much higher activity for the degradation of CR under visible light irradiation compared to the non-doped or to the highly W-doped TiO2.
References
[1] I.Fechete, Y.Wang, J.C.Vedrine, Catal.Today. 189 (2012) 2-27.
[2] M.A. Pena, J.L.G. Fierro, Chem.Rev.101 (2001) 1981.
In terms of kinetics, specifically speaking, the rate of reaction as determined by the concentration, reaction orders, and rate constant with each species in a chemical reaction. By using the concentration of the catalyst and the temperature, the overall reaction rate was determined. The rate constants of K0, Kobs, and Kcat can be derived via the plotting of the absorption at 400nm of p-nitrophenol vs. the concentration of the catalyst imidazole. Lastly, the free energy of activation, G, that is necessary to force the reactant’s transformation of the reactant to the transition state structure will be determined by using the equation G = H – TS derived from the Eyring plot. Introduction: The purpose of the experiment is to study the rate of reaction through varying concentrations of a catalyst or temperatures with a constant pH, and through the data obtained the rate law, constants, and activation energies can be experimentally determined.
Investigation Into the Colour of Light Needed to Start a Photosynthesis Reaction Diagrams [IMAGE] Method The apparatus for this experiment will be setup as shown in the diagram, for all the experiments the coloured filter will be 5cm away from the white light bulb, which is a 60watt bulb, and the beaker will be 20cm away from the edge of the coloured filter. Just before the experiment takes place we will place the pond weed (which has been in darkness for at least 24 hours to stop it any photosynthesis) into the beaker. I will then place the funnel over the pond weed and place the test-tube into the beaker (like the diagram above) I will then fill the beaker up with cold tap water till it covers the bottom of the test tube (450ml).
Lastly, we focus on the transition from α-FePO4 to β-FePO4 with changes in temperature. At low temperatures from 294K to 969K, FePO4 exists as a α polymorph. At 980K, first order transition occurs, as inter-tetrahedral and tilt angles decreases at an increasing rate as temperature increases from
Titanium exhibits a variety of mechanical properties that allows it to be used in different applications. Titanium is extremely resistant to corrosion especially when in close proximity with different media such as human bone, synovial fluid and plasma. This is achieved through the use of a stable and insoluble oxide film that strongly adheres to the surface of titanium. Research has shown that titaniums resistance is considerably better than
Titanium dioxide, also known as Titanium (IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it is sourced from ilminite, rutile and anatase. It has a wide range of applications, from paint to sunscreen to food colouring.
Karthikeyan Krishnamoorthy et al., 2011 has proven that graphene oxide can act as a photocatalytic material because of their photocatalytic properties based on their past research. The photocatalytic characteristics of graphene oxide were investigated by measuring reduction rate of resazurin into resorufin as a function of UV irradiation time. Change in color from blue resazurin into pink resorufin followed by absorption spectra were observe in order to know its progress of photocatalytic reaction.
The Effect of Intensity on the Power of Solar Cells This experiment involves changing the intensity of light falling on different cells and measuring their power outputs. Higher intensity of light means that there are more photons hitting the surface of the cell per unit area per second. The more hit the cell, the more rapidly the electrons move across the p-n junction, so the larger the emf produced. If the rate of movement of electrons is inhibited, then the greater the rate of supply of photons (intensity), the more will not successfully excite an electron, so the lower the efficiency of the cell.
In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established. From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will be established. The goal is to develop a both efficient and effective product (catalyst) using a novel methodology developed from past research.
Copper Sun is a book about a fifteen year old girl named Amari who was stolen from her village by white slave traders, and lived a horrible life as a slave until she finally escaped.
The solution for the resistance to oxidation of p-toluic acid was solved by the discovery of bromide-controlled air oxidation in 1955 that was led to the implementation of AMOCO process [28-31]. In AMOCO process, the oxidation of para-xylene was conducted using a combination of three ions as a homogeneous catalyst which is cobalt, manganese and bromide ions. Acetic acid and oxygen/air were used as solvent and oxidant, respectively [32]. The common bromide ion sources are hydrobromic acid (HBr) and sodium bromide (NaBr). The oxidation operated at 175-225°C and 15-30 bar of oxygen. The terephthalic acid formed mostly in the form of solid due to the low solubility of terephthalic acid in the acetic acid. AMOCO process successfully gives a promising reaction yield, since more than 98% of para-xylene reacted, while terephthalic acid selectivity yield was about 95% in the reaction time of 8-24 hours (Scheme 3).
Graphene has received great mass media coverage since Geim and Novoselov published their foundlings about monocrystalline graphitic films in 2004, which won them the Nobel Prize in Physics in 2010. (Novoselov et al, 2004) It has been described as the wonder substance or super material by the mass media, not only because it is the thinnest material ever known and the strongest ever measured, but also due to its excellent electrical, thermal, mechanical, electronic, and optical properties. It has high specific surface area, high chemical stability, high optical transmittance, high elasticity, high porosity, tunable band gap, and ease of chemical functionalization which helps in tuning its properties (Geim et al, 2007) Moreover, graphene has a multitude of amazing properties such as half-integer room-temperature quantum Hall effect (Novoselov et al, 2007), long-range ballistic transport with almost ten times greater electron mobility than that of silicon, and availability of charge carriers that behave as massless relativistic quasi particle, known as Dirac fermions. (Geim et al, 2007) The outstanding electrical conductivity and the transparency and flexibility of graphene-based material have led to research and development of some future technologies, such as flexible and wearable electronics. In addition, graphene can also be used for efficient energy storage materials, polymer composites, and transparent electrodes. (Geim et al, 2007) This paper presents a
The main purpose of green nanotechnology has been to develop clean technologies that would minimize potential human and environmental health risk. Also, to encourage replacement of existing products with the clean technologies that is more environmentally friendly. There are many benefits of using green nanotechnologies as the new solution for energy in both their current availability and their current development. Over the new few decades, the highest growth opportunities will come from application of nanomaterials for making better use of existing resources. Nanotechnologies will help reduce weight of carbon emission in transportation utilizing nanocomposite materials that quickly diffuses across the automotive and aerospace industries. Applications of nanotechnologies will result in a global annual savings of 8000 tons of carbon dioxide, which will rise even further to over millions tons by 2020. But, let’s focus on the positive effects of Green Nanotechnology in Solar.
The output phosphor, made of zinc cadmium sulfide, is where the electrons produced through photoemission will interact and produce light. It is extremely important that the path of the electrons from the photocathode to the output phosphor be precise.
Compare the final number of moles of TiCl4 (g) produced from both TiO2 (s) and Cl2 (g). (See Figure 17)
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/