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    Adsorptive removal of diclofenac sodium from aqueous solution onto sycamore ball activated carbon - isotherms, kinetics, and thermodynamic study
    (Elsevier, 2021) Avcu, Tarik; Uner, Osman; Gecgel, Unal
    This study reports the analysis data of diclofenac sodium adsorption on sycamore ball activated carbon surface, in which various parameters such as adsorbent dosage, initial diclofenac sodium concentration, temperature, and pH were analyzed. At 25 degrees C, adsorbent dosage was used the range from 2.5 mg/50mL to 30 mg/50mL, and initial diclofenac concentration was taken from 10 mg/L to 50 mg/L. For adsorption temperature effect, adsorption temperature was investigated from 25 degrees C to 45 degrees C by holding adsorbent dosage constant (10 mg/50mL). By holding constant adsorbent dosage of 10 mg/50mL, contact time effect from 0 to 210 min was investigated with initial DS concentrations of 10, 20, 30, 40, and 50 mg/L. To examine pH effect, pH parameters were adjusted from 2.84 to 10.20. Besides, adsorption isotherm model, kinetic and thermodynamic studies carried out in this study are given. Langmuir isotherm model was determined to be the best fitting isotherm model for diclofenac sodium adsorption on sycamore ball activated carbon. Also, the maximum sodium diclofenac adsorption on sycamore ball activated carbon was calculated 178.89 mg/g at 25 degrees C, and kinetic data displayed that this adsorption occurred quite fast. Pseudo-first and pseudo-second order models were applied for sodium diclofenac adsorption on sycamore ball activated carbon, and the correlation coefficient values of 1.000-0.998 indicate that this adsorption was well fitting with pseudo-second order model. Moreover, from the thermodynamic study, sodium diclofenac adsorption on sycamore ball activated carbon was found to be exothermic, spontaneous, and feasible. Thus, the results obtained from this study confirmed that sycamore ball activated carbon is an economically suitable and effective adsorbent for sodium diclofenac adsorption.
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    Comparisons of activated carbons produced from sycamore balls, ripe black locust seed pods, and Nerium oleander fruits and also their H2 storage studies
    (Springer Japan Kk, 2021) Uner, Osman; Gecgel, Unal; Avcu, Tarik
    Starting materials are very significant to produce activated carbons because every starting material has a different chemical structure; hence they affect the surface functional groups and surface morphologies of obtained activated carbons. In this study, sycamore balls, ripe black locust seed pods, and Nerium oleander fruits have been used as starting materials by ZnCl2 chemical activations for the first time. Firstly, activated carbons were obtained from these starting materials with ZnCl2 chemical activation by changing production conditions (carbonization time, carbonization temperature, and impregnation ratio) also affecting the structural and textural properties of the resultant activated carbons. Then, the starting materials and resultant activated carbons were characterized by utilizing diverse analysis techniques, such as TGA, elemental analysis, proximate analysis, BET surface areas, pore volumes, pore size distributions, N-2 adsorption-desorption isotherms, SEM, FTIR spectra, and H-2 adsorption isotherms. The highest surface areas were determined to be 1492.89, 1564.84, and 1375.47 m(2)/g for the activated carbons obtained from sycamore balls, ripe black locust seed pods, and N. oleander fruits, respectively. The yields of these activated carbons with the highest surface areas were calculated to be around 40%. As the carbonization temperature increased with sufficient ZnCl2 amount, N-2 adsorption-desorption isotherms began to turn into Type IV isotherms given by mesoporous adsorbents with its hysteresis loops. Also, their hysteresis loops resembled Type H4 loop generally associated with narrow slit-like pores. Moreover, hydrogen uptakes under 750 mmHg at 77 K were determined to be 1.31, 1.48, and 1.24 wt% for the activated carbons with the maximum surface areas produced from sycamore balls, ripe black locust seed pods, and N. oleander fruits, respectively. As a result, the highest surface areas of the activated carbons with different structural properties produced in this study were obtained with different production conditions.