Browsing by Author "Sert S."

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    Removal of arsenic(III) ions from aqueous solutions by modified hazelnut shell
    (Desalination Publications, 2017) Sert S.; Çelik A.; Tirtom V.N.
    In this study, modified hazelnut shells (HS) were used to remove As(III) ions from aqueous solu­tions. For this purpose, FeCl3 and FeCl3 + NaOH were used as modifying agents. Several important parameters influencing the adsorption of As(III) ions such as contact time, pH, temperature and initial metal concentration were investigated following batch experiments. From the results, it is indicated that temperature 20°C and solution pH = 9.0 are the optimum conditions for adsorption. Maximum adsorption experimental capacities of HS that was treated with FeCl3 and FeCl3 + NaOH were 4.37 and 11.84 mg g-1 for arsenic, respectively. The adsorption data at optimum conditions were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherm models, and it was found that Freundlich isotherm model gives better fit. Thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°) and free energy change (ΔG°) were also calculated. These results were indicated that the adsorption of arsenic on HS is exothermic and proceeds spontaneously. Additionally, it can be said that these adsorptions are physical because the Gibbs free energy change (ΔG°) for both adsorbents were found lower than 20 kJ mol-1. © 2017 Desalination Publications. All rights reserved.
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    Enhancing solar thermal storage properties of azobenzenes with conductive polymer: Electropolymerization of carbazole containing photoactive cyanoazobenzene derivative
    (Elsevier Ltd, 2023) Sert S.; Ayranci R.; Çılgı G.K.; Ak M.
    Solar thermal fuels (STFs) have recently drawn attention as a promising strategy for utilization of solar energy that is a clean and renewable source. Especially solid state solar thermal fuels have high potential to be used in thermal applications. However, up to date, it is seen that the solar thermal storage capacity in the polymeric state is lower than in the corresponding monomers. Herein, for the first time, photoactive azobenzene and electroactive carbazole containing monomer (Cz-AzoCN) was designed and thermal storage properties of the monomer and the corresponding polymer obtained by electropolymerization were investigated. This study showed that polycarbazoles containing azobenzene pendant groups can be an effective thermal storage platform due to their easy functionality, high light absorption and rigid conjugated chain structure resembling the structure of rigid templates decorated with closely packed photochromic units. Additionally, electropolymerization is an easy and rapid method for polymer synthesis, producing polymer in the form of film that is ready for irradiation. The gravimetric energy storage density of p(Cz-AzoCN) was calculated as 145.12 j g−1 which was 128 % higher than that of monomer. This is due to boosted light harvesting of conjugated polycarbazole backbone as an organic photosensitizer that providing effective solar thermal storage. © 2023 Elsevier Ltd
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    Photoresponsive conductive polymer network based on azobenzene bridging crosslinked polycarbazole for boosting solar thermal storage
    (Elsevier B.V., 2024) Sert S.; Ayranci R.; Çılgı G.K.; Ak M.
    Azobenzene is one of the most extensively researched multifunctional chromophores and azobenzene including materials has a wide variety of applications due to their photoisomerization behavior. In this study, electroactive and light-harvesting carbazole and photoresponsive azobenzene units have been combined with a special macromolecular design. In this design the azo groups can be effectively isomerized in solid state, and free-standing films can be obtained by the electrochemical method. Thermal characterizations of both monomer and polymer have been performed and isomerization kinetics and solar-thermal properties have been investigated. The half-life at 60 °C and the gravimetric energy storage density of polymer was calculated as 103 min and 179.9 j g−1, respectively. Cross-linked polycarbazole structure causes dramatically increased solar thermal storage and half-life compared to respective monomer and brought unexpected mechanical and solvatochromic properties. © 2024 Elsevier B.V.