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EN
In this study, magnetite (Fe₃O₄) nanoparticles were synthesized by chemical co-precipitation method, coated with silica, and then the surface of silica coated magnetite (Fe₃O₄@SiO₂) nanoparticles was modified with (3-aminopropyl)triethoxysilane (APTES) at first. Secondly, attained nanoparticles were characterized by the Fourier transform infrared, X-ray diffraction, transmission electron microscopy, the Brunauer-Emmett-Teller, vibrating sample magnetometer, and zeta-sizer devices/methods. Finally, detailed adsorption experiments were performed to remove hexavalent chromium (Cr(VI)) from aqueous media by synthesized nanoparticles. Mean size and specific surface area of synthesized nanoparticles were about 15 nm and 89.5 m²/g, respectively. The highest adsorption capacity among used adsorbents (Fe₃O₄, Fe₃O₄@SiO₂, Fe₃O₄@SiO₂@L) was attained by Fe₃O₄ nanoparticles and it was determined that adsorption capacity of the other two adsorbents was too low when compared to the Fe₃O₄ nanoparticles. Optimum conditions for Cr(VI) adsorption by Fe₃O₄ nanoparticles were: pH, 3; temperature, 55°C; contact time, 90 min; adsorbent concentration, 0.5 g/l and initial Cr(VI) concentration 10 mg/l. Under these conditions, adsorption capacity and removal percentage of Cr(VI) were found to be 33.45 mg/g and 88%, respectively.
EN
Having symmetrical and balanced material properties, polymer matrix composites are increasingly becoming popular due to easiness of construction and are use in the production of aerospace and automotive structures. In the study, we developed polymer composites based on epoxy resins, containing up to 40 wt.% of blast furnace slag and determined their pin-on-disc dynamic friction, wear, Shore hardness and surface roughness values. Wear tests were performed using a pin-on-disc under dry friction conditions, at the loads of 5, 10, 15 and 30 N, using slip velocity of 0.3 m/s and along distance of 500 m. The hardness and wear resistance values increased with the increase in the content of blast furnace slag. Showing the relationship between wear rate and hardness, an equation with parameters dependent on load was provided. There was an increase in the dynamic friction with an increase in the surface roughness. In addition, dynamic friction was an increasing function of the wear rate. The wear surfaces of the polymer composites were analyzed using scanning electron microscopy. It was observed that the wear rate of the epoxy composites and pure epoxy samples ranged from 19.85 to 171.42 mm³/Nm.
EN
Developments in nuclear technology in the last century have lead to the use of radiation in different areas of human activity. These are not just the energetics but also food, agriculture, medicine, industry and science. Thus, radiation has become an inevitable phenomenon in our lives. Since we cannot isolate radiation from our life, the radiation protection methods should be available. As alternatives to conventional radiation prevention methods, such as lead and heavy concrete shielding, more functional materials need to become the focus of research. The development of the least harmful to the environment, easily applicable, flexible radiation shields has become very important. In this study, silicon matrix composite panels, doped with different ratios of barite and boron carbide, were produced and characterized by optical and scanning electron microscopy (SEM). Gamma and neutron radiation shielding properties of these materials were investigated. The results have been compared with the lead as the standard shielding material.
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