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    Investigation of effectiveness of pine cone biochar activated with KOH for methyl orange adsorption and CO2 capture
    (Springer Heidelberg, 2021) Kaya, Nihan; Uzun, Zeynep Yildiz
    In this study, pyrolysis of pine cone, a lignocellulosic biomass, was carried out in a fixed bed reactor. The biochar product obtained was activated by using chemical activation method. KOH was used as the activating agent with the impregnation ratio was 1/4. Activated pine cone biochars were characterized by using analysis techniques such as SEM, BET, and FT-IR. The usage potential of the activated biochar product with a surface area of 1714.5 m(2)/g has been investigated in two different application areas. As the first application area, the CO2 holding capacity of activated biochar was measured by using the thermogravimetric analysis method. The CO2 adsorption capacity of the activated biochar was determined as 160 mg/g (3.64 mmol/g) at 25 degrees C. As a second application area, the effectiveness of activated biochar product in the removal of dyestuff (methyl orange) from aqueous solutions was investigated. The methyl orange adsorption capacity of the activated biochar in optimum conditions (pH 2, temperature of 25 degrees C, initial concentration of 100 mg/L, adsorbent amount 0.8 g/L) was calculated as 109.5 mg/g. Isotherm modeling and kinetic investigations showed that Freundlich and pseudo-second-order models describe the adsorption equilibrium and kinetic behavior well. As a result, this type of biomass could be successfully evaluated in removing both methyl orange dye, which is a potential pollution risk for aquatic environment, and CO2 that is responsible for climate change and greenhouse effect in the atmosphere.
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    Öğe
    Kinetic and thermodynamic studies on the adsorption of Cu2+ ions from aqueous solution by using agricultural waste-derived biochars
    (Iwa Publishing, 2020) Kaya, Nihan; Arslan, Ferhat; Uzun, Zeynep Yildiz; Ceylan, Selim
    In this study, it was aimed to investigate the adsorption properties of the biochars obtained by pyrolysis of hazelnut and walnut shells for removal of copper ions from aqueous solutions. The characterization of raw biomasses and also biochars were performed using TGA-DTG, FT-IR, BET, SEM, partial and elemental analysis techniques. The optimum conditions were determined by investigating the effect of adsorption parameters (initial concentration, temperature, adsorbent amount, pH, contact time and mixing speed) for efficient removal of copper ions from aqueous solution by batch adsorption experiments carried out under different conditions. The highest adsorption efficiencies were recorded as 82 and 86% respectively for hazelnut and walnut shell biochars at pH 4, C-o = 15 ppm, adsorbent dosage = 3 g/L and mixing speed = 600 rpm. Experimental results showed that the adsorption efficiency for copper ions increased with the increase of temperature (T = 45 degrees C) in studies only using biochar obtained from hazelnut shell. While the time of equilibrium in the aqueous solution containing copper ions was determined to be 75 min for walnut shell char, this duration was 30 min for hazelnut shell char. The experimental results were investigated in terms of Langmuir, Freundlich and Temkin isotherm models. Together with the calculated thermodynamic parameters, the adsorption mechanism was explained. In order to determine the kinetic model of the adsorption process, the experimental data were applied to pseudo first-order, pseudo second-order and intra-particle diffusion models, and the model constants were investigated.