http://ir.bdu.edu.et/handle/123456789/1868 Sat, 13 Jan 2001 07:33:12 GMT 2001-01-13T07:33:12Z http://ir.bdu.edu.et/handle/123456789/12159 SYNTHESIS AND CHARACTERIZATION OF COPPER OXIDE/REDUCED GRAPHENE OXIDE NANO COMPOSITE AND ITS PHOTOCATALYTIC DEGRADATION ACTIVITIES OF METHYLENE BLUE DYE Mehariw, Bazezew Copper oxide nanoparticles were deposited on a presynthesized graphene oxide (GO) by successive ionic layer adsorption and reaction method to form CuO/rGO nanocomposite. The crystal structure, vibrational frequency and optical properties of the synthesized CuO/rGO nanocomposite were studied using x-ray diffraction (XRD), Fourier transform infrared (FTIR) and ultraviolet/visible (UV/vis) spectrophotometers, respectively. The results obtained using the XRD indicates that the desired CuO phase was synthesized with crystalline size (D) of about 16.3 nano meter (nm). The results obtained using the FTIR spectrum showed peak at ∼446, 506 and 606 cm-1 corresponds to Cu-O vibrational mode in the CuO/rGO nanocomposite. In addition, the formation of reduced graphene oxide (rGO) from GO is shown by reduced intensities of oxygen containing functional groups in rGO. Similarly, The UV-Vis absorption spectra of CuO/rGO possess an enhanced absorption in the visible region ranging from 400 nm to 800 nm, with corresponding band gap of 1.66 eV. The photocatalytic applicability of the synthesized CuO/rGO composite has been evaluated by photocatalytic removal of methylene blue (MB) dye as a function of time. CuO/rGO and CuO nanoparticle shows 97% and 77% degradation of MB solution in 120 min respectively, showing excellent photocatalytic performance of CuO/rGO in comparison with pure CuO. The degradation follows pseudo first order kinetic with rate constant of 0.012 and 0.025 min-1 for CuO and CuO/rGO composite, showing doubled photodegradiation rate of MB dye under CuO/rGO composite. This is due to the fast charge carrier transport and reduced carrier recombination in CuO/rGO composite due to the presence of rGO. KEY words: Copper oxide, reduced graphene oxide, Photocatalysis, Methylene blue, SILAR Tue, 29 Jun 2021 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/12159 2021-06-29T00:00:00Z http://ir.bdu.edu.et/handle/123456789/12093 CATALYST ASSISTED EXTRACTION OF DIESEL FUEL FROM PURE AND MIXTURE WASTE PLASTICS Nega, Chanie Conventional fossil fuels are widely used as a source of energy for prime movers like IC Engines. The efficient prime movers like diesel engines are usually found applications in a wide array of areas, including industrial, agricultural and transport sectors. The demand for diesel and other petroleum-based fuels across the globe, especially in developing nations such as Ethiopia, has been rising steadily leading to concerns for long-term energy security. Due to a combination of these factors, various research initiatives aimed at developing suitable alternative sources of energy from waste plastic recycling continue to be accepted. To take its part, this thesis mainly concerns the extraction of liquid oil from waste PET and HDPE individually and from their mixture using a catalyzed pyrolysis process carried out in a batch reactor MS system. It searched for the maximum possible liquid oil yield in terms of presence of catalyst, temperature, residence time, feed consumption and waste plastic ratio. The presence of a natural zeolite catalyst is found to increase the liquid oil yield of the pyrolysis process. The conversion efficiency increases for pure PET (38.1 to 43.5 wt%), pure HDPE (72.8 to 84.6wt%) at 10% catalyst with a processing residence time of 45 minutes. The liquid conversion efficiency for 1:4 ratio of HDPE to PET is 65.3wt%, but it becomes 78.4wt% when the ratio is 4:1, processed at optimum temperature of 425 and 10% catalyst. The physical properties like density, calorific value, pour point and viscosity of the liquid oil extracted from waste plastic are finally tested using respective characterizing machines to justify its correlation with pure diesel fuel. The FTIR and TGA are used to investigate the functional group and weight loss, respectively, of the liquid oil extracted from waste plastic. Engine performance like brake powers ( ), brake torque (Tb) and brake specific fuel consumption (bsfc) were also evaluated. Numerically, PET, diesel fuel, HDPE, and mixed waste plastic fuels have an average brake torque of 2.455, 2.25, 2.315 and 2.36 Nm respectively. The Tb of PET waste plastic fuel is 0.205(8.37%), 0.14(6.05%) and 0.091Nm (3.86%) higher than pure diesel fuel, HDPE and mixed waste plastic fuel respectively. Diesel, HDPE, Mixed and PET fuels have average outputs of 1.79, 1.83, 1.94 and 2.06kW respectively. The fuel consumption of all fuels decreases with increasing the engine speed. When comparing the specific fuel consumptions to each other, the average fuel consumptions are 0.29, 0.285, 0.285 and 0.279 kg/kWh for pure diesel, HDPE, Mixed and PET, respectively. Keywords: Engine performance, alternative fuel, fuel properties, pyrolysis, waste plastic, catalyst Fri, 14 May 2021 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/12093 2021-05-14T00:00:00Z http://ir.bdu.edu.et/handle/123456789/12035 Partial replacement of cement by waste glass for concrete production. Zemenu, Ngus Reusing of waste glass in concrete production is among the attractive option of achieving waste reduction and preserving the natural resources from further depletion thereby protecting the environment and achieving sustainability and producing concrete. This study systematically investigated the possible reuse of waste glass powder as partial substitute for cement in concrete. The concrete were prepared using a mix proportion of 1:2:4 (cement: fine aggregate: coarse aggregate) at water-cement ratio of 0.5 targeting a design strength of 25 MPa. We measured compressive strength, split tensile strength and flexural strength of concrete samples, that cement partially replaced by waste glass with the ratio of 5%, 10% and 15% by mass.The test result shows that the replacement of glass powder improves the mechanical properties of concrete as compared to normal concrete, with the peak value at 10% replacement of cement with glass powder. The maximum Compressive strength value appears on 10% of cement replacement with glass powder by mass. As curing age increase the Compressive strength of concrete also increase and the hydrations of cement is faster than glass powder. Split tensile strength of concrete Increased as curing time increased, and shows pick value at 10% glass powder replacement, and above 10% replacement the split tensile strength is decreased because of loses of first hydration energy of cement. The evolution of flexural strength of the original design mix and 10% of glasses that work as a partial replacement of cement with curing age, The results pointed out that the strength of concrete increases proportionally with curing process because the hydration process still continuous until getting the full strength of concrete. The flexural strength of 10% glass replacement as cement is greater than conventional concrete. The replacement of glass powder is economically cheap as well as a superior concrete can be made and it reduces emissions of CO2 to produce cement. Keywords: waste glass powder, pozzolanic reaction, cement, concrete. Thu, 04 Mar 2021 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/12035 2021-03-04T00:00:00Z http://ir.bdu.edu.et/handle/123456789/12034 Investigation of Mechanical Properties of Hybrid Nettle-E glass Fiber Reinforced Epoxy Composite: A Numerical and Experimental Approach TSEGAYE, CHEMERE Natural fibers have been found to be excellent reinforcing materials for preparing natural fiber reinforced thermoplastics (NFRT). From that, natural fiber plants like nettle are available in many parts of Ethiopia. The main objective of this study is to fabricate and characterize the mechanical property, such as impact, tensile and bending strength of nettle/glass fiber hybrid composite with epoxy Resin. The hybrid composites were fabricated with nettle fiber: glass fiber: epoxy resin weight percentage at [40%:0%:60%], [30%:10%:60%], [20%:20%:60%], and [10%:30%:60%] by hand lay-up method. Once the samples were fabricated, the test pieces were cut according to ASTM standards and the tests were conducted on Charpy impact testing machine and universal testing machine. The maximum tensile strength, flexural strength, and impact energy were found to be 248.44 MPa, 967.2 MPa, and 60.03 KJ/m2 , respectively as a function of fiber weight fraction. According to the results, the hybrid composite with [30%:10%:60%] weight percentage exhibited the best tensile and bending strength, whereas the [20%:20%:60%] weight ratio displayed the best impact test compared to the rest proportions. The test results of the samples were also analyzed using Finite Element Analysis with ANSYS software to validate the experimental results. Key Words: Nettle Fiber, Glass fiber, Epoxy, Composite, Hand layup fabrication technique, Tensile, Impact and Flexural properties. Thu, 04 Mar 2021 00:00:00 GMT http://ir.bdu.edu.et/handle/123456789/12034 2021-03-04T00:00:00Z