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Öğe Magnetite nanoparticles grafted with murexide-terminated polyamidoamine dendrimers for removal of lead (II) from aqueous solution: synthesis, characterization, adsorption and antimicrobial activity studies(Journals & Books, 2021-03) Ekinci, Selma; İlter, Zülfiye; Ercan, Selami; Çınar, Ercan; Çakmak, ReşitIn this study, new, efficient, eco-friendly and magnetically separable nanoadsorbents, MNPs-G1-Mu and MNPs-G2-Mu, were successfully prepared by covalently grafting murexide-terminated polyamidoamine dendrimers on 3-aminopropyl functionalized silica-coated magnetite nanoparticles, and used for rapid removal of lead (II) from aqueous medium. After each adsorption process, the supernatant was successfully acquired from reaction mixture by the magnetic separation, and then analyzed by employing ICP-OES. Chemical and physical characterizations of new nanomaterials were confirmed by XRD, FT-IR, SEM, TEM, and VSM. Maximum adsorption capacities (qm) of both prepared new nanostructured adsorbents were compared with each other and also with some other adsorbents. The kinetic data were appraised by using pseudo-first-order and pseudo-second-order kinetic models. Adsorption isotherms were found to be suitable with both Langmuir and Freundlich isotherm linear equations. The maximum adsorption capacities for MNPs-G1-Mu and MNPs-G2-Mu were calculated as 208.33 mg g−1 and 232.56 mg g−1, respectively. Antimicrobial activities of nanoparticles were also examined against various microorganisms by using microdilution method. It was determined that MNPs-G1-Mu, MNPs-G2-Mu and lead (II) adsorbed MNPs-G2-Mu showed good antimicrobial activity against S. aureus ATTC 29213 and C. Parapsilosis ATTC 22019. MNPs-G1-Mu also showed antimicrobial activity against C. albicans ATTC 10231.Öğe Comparative experimental investigation on the effects of heavy alcohols- safflower biodiesel blends on combustion, performance and emissions in a power generator diesel engine(Elsevier, 2021-02-05) Işık, Mehmet ZerrakkiThe experimental works carried out in this article evaluates the potential of using heavy alcohol and safflower biodiesel as the blended fuel mixtures without making any modifications in the tests diesel engine. For this purpose, volumetrically 20% of Propanol, Pentanol, Butanol, and Octanol were blended with safflower biodiesel fuel and they were named as PR20, PE20, BU20, and OC20, respectively. The performance, combustion, and emission data were found out at the same conditions of constant engine speed and various loads and compared with pure biodiesel (B100) and diesel fuel(ULSD). In the experiments, a four-cylinder, water-cooled diesel engine that was loaded by an electrical power generator was used for the tests. The addition of alcohol causes an increase in fuel consumption due to a decrease in lower thermal performance. The use of heavy alcohols in diesel engine in specific quantities by mixing with biodiesel significantly increases engine brake thermal efficiency. Negative effects of low cetane number and high latent heat of vaporization that may decrease ignition delay and decrease cylinder pressure while increase peak heat release was considered to be compensated by the better mixing properties and atomization of alcohol blended biodiesel thus eventually improve the combustion. Alcohol addition to biodiesel fuel can be accepted as a useful application to increase brake thermal efficiency and reduce nitrogen oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC) emissions by reducing the density and viscosity.Öğe Effects of isopropanol-butanol-ethanol (IBE) on combustion characteristics of a RCCI engine fueled by biodiesel fuel(Journals & Books, 2021-10) Altun, Şehmus; Okcu, Mutlu; Varol, Yasin; Fırat, MüjdatThe reactivity controlled compression ignition (RCCI) strategy using fuels with different reactivity’s has attracted attention due to its high thermal efficiency as well as very low NOx and PM emissions in comparison to conventional combustion. As previous studies have shown that the type and amount of low reactivity fuel have a significant contribution to the in-cylinder reactivity, thus RCCI combustion, in this study, Iso-Propanol-Butanol-Ethanol (IBE), which has comparable characteristics to n-butanol and ethanol, is employed as low reactivity fuel (LRF) in a RCCI engine fueled by petroleum based EN590 fuel and commercial biodiesel. The IBE mixture was in volumetric ratios of 3:6:1 as in the fermentation process of butanol, that is to say; 30% Iso-Propanol, 60% Butanol and 10% Ethanol. In each experimental condition, keeping the total energy of the fuel supplied to the engine in conventional combustion mode for each cycle as constant, the premixed ratio (Rp) in case RCCI combustion was applied as 0%, 15%, 30%, 45% and 60% (the amount of LRF in energy basis) over this energy amount. The effect of premixed ratio of IBE on combustion characteristics were investigated in a single-cylinder RCCI engine under different loads with using both petroleum diesel and biodiesel as high-reactivity fuels (HRF), respectively. According to experimental results, a higher in-cylinder pressure was measured by using diesel in both conventional and RCCI mode compared to the use of biodiesel. Considering the peak in-cylinder pressure and rate of heat release, the premixed ratio (Rp) of up to 45% was found as optimum for all loads while it was up to 30%Rp for the NOx emissions. In addition, the biodiesel-fueled RCCI engine produced the lowest smoke opacity in all loads and it gradually decreased by up to 97% with the application of the RCCI strategy. Furthermore, the results showed that a simultaneous reduction in NOx and smoke opacity could be obtained under 60% load and up to 30% Rp with a marginal increase in unburned HC emissions.Öğe An innovative research on variable compression ratio in RCCI strategyon a power generator diesel engine using CNG-safflower biodiesel(Elsevier, 2021-09-15) Aydın, HüseyinThe CNG usage as a fuel in IC engines have many advantages such as decreasing CO2and PM and smokeemissions and in many cases reducing NOx emission, along with its low prices and naturally abundancespread on the world. In heavy loaded operation of diesel engines, it becomes very hard to controlexcessive NOx, and PM formation in the exhaust emissions and smoke accumulation especially forbiodiesel usage. In the present study, in order to achieve the usability of higher percentages of biodieselwith CNG, the low temperature combustion of reactivity controlled compression ignition (RCCI) strategyhave been applied in a single cylinder diesel engine with variable compression ratios. The CNG, as thelow reactivity fuel, was subjected to the intake manifold as the substitute the gas with 5%, 10% and 15% ofbiodiesel under 1500 rpm and 10.8 kW(full load) load of the engine with variable compression ratiosfrom 13:1 to 19:1 in order to investigate the effects of compression ratios on RCCI operation with highpercentages of biodiesel and CNG usage. Apart from the main performance, emissions and combustionindicators of diesel engines tests, 3 novel parameters (SPE, STE and SHRE) were created for thefirst timein order to deeply evaluate the combustion. Mean of cylinder pressure was increased while combustionduration was lowered for CNG usage with biodiesel. BTE was increased while BSEC and BSFC weredecreased in either operation of biodiesel/CNG RCCI and various CR. In addition, NOx emissions werelowered for CNG usage and CR decrease, along with smoke decrease for biodiesel/CNG RCCI combustion.Öğe Production of mixed rare earth oxide powder from a thorium containing complex Bastnasite ore(Journals & Books, 2021-02) Özsaraç, Şafak; Kurşunoğlu, Sait; Hussaini, Shokrullah; Top, Soner; Ichlas, Zela Tanlega; Gökçen, Hasan Serkan; Kaya, MuammerThe production of mixed rare earth oxide powder from a thorium containing bastnasite ore by sulfuric acid bake-water leaching followed by precipitation with oxalic acid and thermal decomposition of the oxalates was investigated. The sulfuric acid baking was performed at 250 °C and the optimum baking time was found to be 3 h. Using deionized water as lixiviant, 92.6% La, 86.8% Ce, 86.9% Pr, 82.3% Nd, 95.4% Th and 31% Y were dissolved from the baked ore at 25 °C after 30 min of leaching. The effect of solid-to-liquid ratio on the dissolution of the rare earth elements and thorium shows that when the solid ratio in the water increased from 1:10 to 1:3, the dissolution percentage decreased. The final mixed rare earth oxide powder contained 88.54% REO and 6% ThO2 together with small amounts of other impurities. The SEM mapping results revealed that the produced REO has an irregular crystal shape. Based on the experimental results obtained from the current study, a flowsheet was proposed for the production of mixed rare earth oxide powder from a specific complex bastnasite ore.Öğe Investigation of the effect of barium-based additive on smoke and NOx emissions of a diesel engine fueled with conventional and biodiesel fuels(SpringerLink, 2020-06-13) Altun, Şehmus; Arca Batı, ZülalNowadays, increasing energy demand and environmental and air pollution issues have spread the use of alternative fuels such as biodiesel in diesel engines. While the advantages of biodiesel that are comparable to petroleum-based diesel fuels and low unburned HC, carbon monoxide and smoke (soot) emissions make the use of this fuel environmentally signifcant; high NOx emissions are still a problem to be solved. The formation of decreased smoke reducing radiative heat transfer from combustion chamber in biodiesel engines and increase in formation of NOx due to rise in fame temperature are among the reasons reported for high NOx in the literature. In this study, in a diesel engine using biodiesel, soot emissions produced by petroleum diesel fuel were reduced to biodiesel level by using metallic additive (Ba), and NOx emissions were compared. When the amount of Ba in the fuel was increased, there was a signifcant decrease in the smoke emissions, but in this case, NOx emissions decreased slightly, while they were expected to increase. When NOx emissions of diesel and biodiesel were compared for the same or similar smoke emissions, it was seen that high NOx emissions were achieved with biodiesel. As a result, although Ba additive reduced smoke emissions, it was seen that its efect on NOx formation was not very clear.Öğe Correlation formulation for optimum tilt angle for maximizing the solar radiation on solar collector in the Western Himalayan region(Journals & Books, 2021-01) Kallioğlu, Mehmet Ali; Sharma, Ashutosh; Awasthi, Anchal; Chauhan, Ranchan; Fekete, Gusztáv; Singh, TejSolar tracking devices are efficacious in maximizing solar irradiation collection. However, higher price makes these systems less frequently used. As an alternative, optimum tilt angle estimation has the advantage that it does not involve tracking cost expenditure. In this study, optimum tilt angles for different months have been computed for Hamirpur, Himachal Pradesh, India (L 31° 42′ N). Several mathematical models and statistical tools have been employed to forecast the monthly optimum tilt angles for the selected site. Different scenarios have been presented by considering five, four, three, and two annual adjustment models to increase the practical usage of the estimated optimum tilt angles. Additionally, cost-benefit analysis has also be performed on the PV panels. Based on the results, it has been concluded that model M − 11, with three annual adjustments, stipulates maximum benefits over the other models. This study can serve as fundamental guidance for setting up solar energy plants in this specified region with the highest efficiency.
