Ozge Yuksel Orhan

CO2 utilisation: Waste or resource for chemical industry

S the isolation in 2004 graphene continues to attract significant attention from the scientific community. Despite of the fact that graphene is under detailed investigation more than 10 years it still serve as a source for unusual effects. Here I will show that multilayer graphene surface can be used a base for formation of diamond nanofilms [1] facilitated by chemical adsorption of adatoms on the multilayer graphene surface, and explain how the pressure of phase transition is reduced and formally turns negative. For the first time we obtain, by ab initio computations of the Gibbs free energy, a phase diagram (P, T ,h) of quasi-two-dimensional carbon— diamond film versus multilayered graphene. It describes accurately the role of film thickness h and shows feasibility of creating novel quasi-2D materials. In such “chemically induced” phase transition both chemistry and compression concurrently serve as the driving factors for diamond film formation. I will continued to discuss this effect through the ultrastiff films with hexagonal diamond (lonsdaleite) type structure and further show that under the particular external conditions and using particular adsorbate atoms films with the specific structure can be formed [3]. The process of diamond phase nucleation was further investigated on the atomic level. The critical size of graphene hydrogenated region which can initiate graphene diamondization was estimated. The nonlinear dependence of size of graphene hydrogenated region upon the number of layers predicted the maximal thickness of the film which can be formed by chemically induced phase transition [3]. This research was supported by Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (No К2-2015-033).A driven LEDs show very high wall plug efficiency combined with a good colour rendering and long-term stability. For general lighting, LEDs have surpassed the traditional incandescent and fluorescent lamps years ago. (1) However, LEDs still have a tremendous drawback, which is known as flicker. Perceived flicker is caused by the time dependant variation of the luminous intensity of a light source. The consequences for humans under such illumination situations expand from headaches to neurological problems, even including epileptic seizure (2). Since many research activities in this field are conducted to solve or to reduce problems accompanied by flicker, we came up with a possible solution to it. Since the zero point of an AC current cannot be turned out completely, the solution must be based on the used conversion layer (mostly a phosphor particle or ceramic layer) or a combination of a driver systems and the used converter in order to smoothen the Flicker to 100%. In this work a couple of standard LED phosphors have been tested, such as Y3Al5O12:Ce 3+, BaMgAl10O17:Eu 2+Mn2+, CaAlSiN3:Eu 2+, Ca3Sc2Si3O12:Ce 3+Mn2+ and Sr2P2O7:Eu 2+Mn2+ with respect to flicker reduction. It will be demonstrated why Y3Al5O12:Ce 3+ won’t lead to a solution for this problem and possible solutions will be discussed. The capability of other phosphors to reduce flicker will be shown. From these findings requirements for the development of novel phosphors to reduce the flicker problem will be drawn. A prediction will be given concerning the future potential of this technique and achievments so far will be presented.YPO4 is a radiation stable wide band gap material (∆BG = 9.2 eV) which turns into a very efficient UVC / VUV emitter upon doping with e.g. Pr3+, Bi3+, or Nd. [2],[3] Doping with Bi3+ leads to an emission band peaking at 241 nm due to a s-p transition of the [Xe]4f145d106s2 cation, whereas a doping with Pr3+ or Nd3+ leads to a maximum emission around 235 and 192 nm, respectively. This emission is due to f-d transitions of the trivalent lanthanides. 1. Phosphor converted Xe DBD lamps

Utilization of CO2 in petrochemical plants

M wild plants commonly used in folk medicine, such as different species from the genus Lathyrus, may represent new sources of biologically active compounds. Therefore, the study of the composition and (bio)chemical behaviour of extracts from these plants may provide valuable information. Several Lathyrus species have been studied: L. aureus, L. pratensis, L. czeczottianus and L. nissolia. Extracts from these plants were analyzed by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn) to determine their phenolic profile. The in vitro antioxidant activity and enzyme inhibitory evaluation were also investigated. The main phenolic compounds (flavonoids and saponins, mainly) and the antioxidant and enzyme inhibition results are here reported. The phenolic contents and the (bio)chemical properties of the analyzed extracts presented significant variations in the different Lathyrus species. However, the high number of phenolic compounds and the antioxidant and enzyme assays suggest that these plants may be further used in phytopharmaceutical or food industry applications.

The Absorption Kinetics of CO 2 into Ionic Liquid—CO 2 Binding Organic Liquid and Hybrid Solvents

Carbon dioxide (CO2) capture is a global concern because of its effect on climate change especially as regards to global warming. Among greenhouse gases, CO2 is the most abundant with high concentration released from post combustion processes into the atmosphere. For instance, the volume of CO2 emission from thermal power plants, petroleum refineries, petrochemical plants, hydrogen and cement factories has become one of the top important global concerns nowadays. In order to capture post-combustion CO2 and securely store it way or to produce useful products from it, it requires separation of CO2 from flue gas stream. Industrially, it is generally accepted that the most appropriate method that can be applied commercially to capture CO2 involves absorbing it with a reversible reaction from gas streams into aqueous amine especially monoethanolamine. Although, CO2-aqueous amine process is accepted as a mature technology but its absorption/desorption systems are the subject of several studies as the process is energy-intensive among other issues. In view of the shortfalls of CO2-aqueous amine systems and the greater societal concern to control the amount of CO2 released to the environment from industrial sources to abate its effects, research for alternative viable solvent systems becomes of high interest to researchers as well as industrialists. Hence, this chapter is mainly to focus on highlighting and discussing relevant advanced solvent systems for CO2 capture. Among the novel solvents or technology worthy of discussion here include use of organic solvents consisting of an amidine or a guanidine and a linear alcohol, such as 1-hexanol, instead of aqueous amines. In this case, CO2 loaded solvent could be regenerated at 90–100 °C which is much lower than the boiling point of the solvent and as a result, sufficient drop in energy requirements could be achieved. In order to be applicable, CO2 binding organic liquid systems (“CO2BOLs”) will react with CO2 at sufficient rates. In case, the reaction rate is not sufficient it can be upgraded with piperazine derivatives. Another potential novel method is the capture of CO2 by special liquids which have negligible vapor pressure and high thermal stability known as ionic liquids (ILs). The ILs also have favorable CO2 solubility and a wide liquid state temperature with tunable physicochemical characteristics. Further advanced approach can be to develop a blended solvent which can also react with CO2 more efficiently. A blended system is a hybrid that possesses combined benefits of the amines mixture components thereby providing a better alternative than using single component. Other novel solvents for post combustion CO2 capture are noted and discussed here.

Kinetics of CO 2 Capture by Carbon Dioxide Binding Organic Liquids

Carbon dioxide emissions from thermal power plants, hydrogen, and cement factories became one of the most important global concerns. Therefore, development of new sorbent materials and capture technologies to efficiently and economically remove CO2 gained importance. In the scope of this work, novel carbon dioxide binding organic solvents (CO2BOLs) were developed by blending an amidine (or a guanidine) and a 1-hexanol at various concentrations. As an amidine and a guanidine, DBN (1,5-Diazabicyclo[4.3.0]non-5-ene) and TBD (1,5,7-Triazabicyclo[4.4.0]dec-5-ene) respectively were investigated. Experiments were carried out by varying organic base (amidine or guanidine) percentage in 1-hexanol medium and “intrinsic” reaction rates were measured in “stopped flow” equipment for a temperature range of 288–308 K. It was found that the kinetic data could be fitted satisfactorily to a termolecular reaction mechanism and the activation energies for carbon dioxide capturing organic liquids were also obtained.