Yazar "Kaskun, Songul" seçeneğine göre listele

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    Assessment of H2S and BTEX concentrations in ambient air using passive sampling method and the health risks
    (Springer, 2021) Ulutas, Kadir; Kaskun, Songul; Demir, Selami; Dincer, Faruk; Pekey, Hakan
    Wastewater treatment plants (WWTPs) may be a source of nuisance in neighbouring places due to hydrogen sulphide (H2S) and BTEX (benzene, toluene, ethylbenzene, and xylenes) emissions. In this study, samples were collected from WWTP workplace ambient air and outdoor ambient air around one of the largest WWTPs in Istanbul with a capacity of 250,000 m(3)/day to evaluate the effects of H2S and BTEX emissions. Samples were collected in three seasons for 15-day durations: winter (November 2015), spring (May 2015), and summer (August 2016). Average concentrations of H2S and BTEX were determined as 1.1 and 56.2 mu g/m(3), respectively. Average concentrations BTEX components were 4.9, 20.7, 6.4, and 24.2 mu g/m(3), respectively. Health risk assessment for plant workers and local residents was performed for H2S and BTEX inhalation exposure using the method by USEPA. Results show that H2S and BTEX emissions do not have harmful effects on human health.
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    Enhancement of biogas production using SnO2 nanoparticle-doped mica catalyst
    (Springer Heidelberg, 2023) Kaskun, Songul; Calhan, Rahman; Akinay, Yuksel
    Different additives are used to enhance the microbial activity and ensure the suitable environment for anaerobic microorganisms in anaerobic digestion (AD) process. This study aims to investigate biogas production activity by adding mica particles (MP) and SnO2 nanoparticles (NPs)-doped mica (MSnO2) preparing by co-precipitation. The morphological and structural investigations of particles prove that the SnO2 NPs have been successfully embedded on mica surface. The deposition of SnO2 on the mica surfaces contributes the catalytic performance which in turn improves biogas production. The concentration of MP and MSnO2 was adjusted to be 0.03 mg/L and 0.06 mg/L for the biogas production experiment. In batch experiments, the highest biogas production, biogas yield, and methane yield were obtained at MSnO2-1 (0.03 mg/L) with 6890.2 mL, 245.4 ml/gVS, and 162.3 mL CH4/gVS, respectively. The addition of 0.03 mg/L MSnO2 increased biogas yield by 18.1% and methane yield by 33%, in the light of the data acquired from this experimental study that MSnO2 and pristine mica can be used effectively to enhance biogas production from cattle manure (CM).
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    Healthcare waste management practice in the West Black Sea Region, Turkey: A comparative analysis with the developed and developing countries
    (Taylor & Francis Inc, 2015) Ciplak, Nesli; Kaskun, Songul
    The need for proper healthcare waste management has been a crucial issue in many developing countries as it is in Turkey. The regulation regarding healthcare wastes in Turkey was updated in 2005 in accordance with the European Union (EU) waste directives, but it still falls behind meeting the requirements of current waste treatment technologies. Therefore, this study aims to reveal deficiencies, inconsistencies, and improper applications of healthcare waste management in the western part of the Turkish Black Sea Region. In this study, it was revealed that nearly 1 million people live in the region, resulting in 5 million hospital admissions annually. All the healthcare waste produced (1000 tons yr(-1)) is treated in an autoclave plant. However, treating some categories of healthcare wastes in autoclave units mismatches with the EU waste regulations, as alternative treatment technologies are not technically able to treat all types of healthcare wastes. A proper waste management system, therefore, requires an internal segregation scheme to divert these wastes from the main healthcare waste stream. The existing malpractice in the region could cause serious health problems if no measure is taken urgently. It is expected that healthcare waste management in the region and then all across Turkey will be improved with the significant deficiencies and inconsistencies pointed out in this research.Implications:In developed countries, specific rules and regulations have already been implemented along with the recommendations for handling of healthcare waste. However, in Turkey, these wastes are treated in autoclave units, which mismatches with the European Union waste regulations, as alternative treatment technologies are not technically capable to treat all types of healthcare wastes. The existing malpractice could cause serious health problems if no measure is taken urgently. The authors demonstrated the existing status of Turkish waste management and revealed deficiencies, inconsistencies, and improper applications in comparison with developed and developing nations to align Turkish practice to European Union requirements.
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    Improved hydrogen adsorption of ZnO doped multi-walled carbon nanotubes
    (Pergamon-Elsevier Science Ltd, 2020) Kaskun, Songul; Akinay, Yuksel; Kayfeci, Muhammet
    Hydrogen storage is still one of the most important problems to improve hydrogen energy usage widespread. New materials capable of storing hydrogen with high efficiency must be introduced to overcome this problem. In recent years, addition of metals or inorganic compounds to multiwalled carbon nanotubes (MWCNTs) has been generally used for hydrogen uptake studies to enhance adsorption property of the nanotubes. In this study, Zinc oxide (ZnO) nanoparticles doped MWCNTs (ZnO-MWCNTs) have been produced as new reversible hydrogen storage materials, and we have investigated characterization of ZnO-MWCNTs by XRD, SEM, TGA, TEM and BET analyses. The functionalized MWCNTs and ZnO doped MWCNTs were subjected to hydrogenation step by dynamic gas sorption analyser under pressure of 5-50 bar. The hydrogen uptake capacities of the materials under different pressures were measured gravimetrically. It was indicated that by controlling the pressures for hydrogenation of ZnO-MWCNTs induces the spillover of ZnO nanoparticles in the layer of MWCNTs which in return with high hydrogen adsorption capacity. Consequently, the hydrogen adsorption of the functionalized MWCNTs (fMWCNTs) and the ZnO-MWCNTs were achieved to be 1.05 wt% and 2.7091 wt% under pressure of 50 bar as maximum. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    The synthesized nickel-doped multi-walled carbon nanotubes for hydrogen storage under moderate pressures
    (Pergamon-Elsevier Science Ltd, 2018) Kaskun, Songul; Kayfeci, Muhammet
    Hydrogen adsorption capacity of Multiwalled carbon nanotubes (MWCNTs) decorated with Nickel (Ni) nanoparticles has been presented at room temperature and under moderate pressures of 4-20 bar. The functionalization of carbon nanotubes was carried by H2SO4-HNO3 reducing agents and the Ni supported MWCNTs (Ni-MWCNTs) were prepared by wet chemical method. The structure and morphology characterization of samples were performed by XRD, TEM, EDX and SEM analyses. These nanotubes then subjected to hydrogenation step by using Sievert's-like apparatus. The hydrogenation of the Ni-MWCNTs was performed at 298 K and moderate hydrogen pressures of 4-20 bar. The obtained results show that there is a correlation between hydrogen storage capacity and hydrogen pressure that; as the pressure was increased, hydrogen uptake capacity enhanced due to physisorption. In addition, maximum hydrogen storage capacity of Ni-MWCNTs was found to be 0.298 wt % at room temperature and under pressure of 20 bar. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.