The adsorption of carbon dioxide (CO) on activated carbon (AC) prepared from olive trees has been investigated by using a fixed bed adsorption apparatus. The adsorption equilibrium and breakthrough curves were determined at different temperatures 30, 50, 70, and 90°C in order to investigate both kinetic and thermodynamic parameters. Maximum CO 2 sorption capacity on AC ranged from 109.5 to 35.46 and from 129.65 to 35.55 mg CO 2 /g of AC for initial concentrations 10 and 13.725% vol., respectively. Different isotherm models are applied to mathematically model the CO 2 adsorption, and on the basis of the estimated adsorption capacity by model and determination coefficient (r 2), the Langmuir model provides a perfect fit to the experimental data owing to closeness of the r 2 to unity. From the correlation coefficient, it is found that the pseudo-second-order model is well-fitted with the experimental data. In addition, it indicates that CO 2 adsorption is a physical adsorption process and demonstrates a behavior of an exothermic reaction, which is consistent with the thermodynamic analysis. The results obtained in this study conclude that AC prepared from olive trees can be considered as adequate for designing a fixed bed cycle to separate carbon dioxide from flue gases and serve as a benchmark while searching for inexpensive and superior activated carbon production in future studies.
Urethane macromonomers (UMs) having different urethane chain lengths (X) were synthesized by the reaction of an isocyanate-terminated prepolymer with 2-hydroxy ethyl methacrylate (HEMA) and isopropanol. The existence and the structural identification of the UMs were verified by FTIR, 1 H NMR and 13 C NMR spectroscopy. Various percentages of the respective UMs (0-40 wt % acrylate monomers) were then incorporated into methyl methacrylate (MMA) and n-butyl methacrylate (n-BMA) backbones via solution free-radical copolymerization. The resulting methyl methacrylate-g-urethane and n-butyl methacrylate-g-urethane copolymers were characterized by GPC, 1 H NMR, 13 C NMR, FTIR, TGA and DMA. Phase separation between the urethane segment and the acrylate segment in the graft copolymerization products was investigated by DMA and TEM. DMA results showed that in most graft copolymer products the two respective component parts of PMMA-g-urethane or n-PBMA-g-urethane were compatible as only one T g was observed. Two glass transitions, at temperatures of 22 and 76 o C, corresponding to the n-PBMA and urethane moieties, were observed when the chain length of the UMs was increased from X=4 to X=32. Microphase separation was also evident in TEM measurement.
Built during the seventies and commissioned in 1980, Khoms Steam Power Plant consists of four units. A proposed design modifications based on Hysys simulation is to improve the overall efficiency, reduce gas emissions and lower operation and maintenance costs.Five proposed modifications based on reduction of heat loss from the condenser and lowering heating rate reveal that a single open feedwater heater process is the optimum design modification of Rankine cycle to achieve the targeted objectives.
Ground water is the most reliable source of drinking water and frequently contains ammonia as a pollutant in concentrations up to 3mg/L. The recommended maximum concentration level (MCL) according to the World Health Organization (WHO) is 0.5 mg/L. Concentrations in excess of this in drinking water can be oxidized to toxic nitrite, support the growth of bacteria, (Nitrosomonas and Nitrobacter), and create taste and other problems in treatment plants and the distribution network. High ammonia concentrations also create high chlorine demand during disinfection that consequently produces trihalomethanes and organochlorines suspected to be carcinogenic. In this work the biological oxidation of ammonia to nitrite and consequently to nitrate by nitrifying bacteria, Nitrosomonas and Nitrobacter was studied in two fluidized bed reactors, each having one type of biofilm supporting material: sand and granular activated carbon (GAC). The aim was mainly to investigate the possibility of ammonia oxidation to nitrate when the ammonia concentration is low, and how the support materials influence the starting up period and the rate of ammonia oxidation capacity of the nitrification process. In this study the main equipment used were two reactors and an aerator, which were made of Plexiglas tubes. Synthetic water containing ammonia nitrogen (1-3 mg/L) was fed to the reactors in fluidization mode. Both GAC and sand reactors gave ammonianitrogen (NH 4 + -N) oxidation capacity up to 2.5 kg/m 3 of nitrogen per day. The type of the support material that was found to be successful in nitrification is GAC. Nitrification in the sand reactor proceeded at a very slow rate compared to the GAC reactor. The GAC reactor had a higher oxidation rate and steeper curve compared to the sand reactor and reached maximum nitrite production earlier than the sand reactor.
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