Sürdürülebilir Kalkınma Amaçları
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- MakaleYalnız künye2013Scopus SJRQ3Bacteria-modified red mud for adsorption of cadmium ions from aqueous solutions
Kalkan, Ekrem; Nadaroglu, Hayrunnisa; Dikbaş, Neslihan; Taşgin, Esen; Çelebi, Neslihan
Cadmium is a toxic metal widely used in industry and it enters the environment from electroplating, smelting, alloy manufacturing, pigments, plastics, cadmium-nickel batteries, fertilizers, pesticides, mining, pigments and dyes, textile operations, and refining industries. Considering the harmful effects of cadmium, it is necessary to remove cadmium from liquid wastes at least to the limit accepted by regulations. The present study describes removal of cadmium from aqueous solutions using bacteria-modified red mud waste material. Batch adsorption experiments have been performed as a function of pH, contact time, temperature, and adsorbent dosage. The optimum results were obtained at pH 4.0, contact time of 60 min, temperature of 30°C, and an adsorbent dose of 1 mg/mL. The adsorption data was correlated with Langmuir and Freundlich adsorption models. The maximum adsorption capacity obtained from Langmuir adsorption model was 83.034 mg/g. The kinetic processes of cadmium adsorption on bacteria-modified red mud were described by applying pseudo-first-order and pseudo-second-order rate equations. The kinetic data for the adsorption process obeyed pseudo-second-order rate equations. Various thermodynamic parameters, such as ΔG°, ΔH°, and Δ15° were calculated and the negative value of ΔG° obtained indicate that the process was spontaneous, and the positive value of ΔH° confirms the reaction to be endothermic, and the positive value of ΔS° shows that the decrease in the degree of freedom of the adsorbed species. The bacteria-modified red mud investigated in this study exhibited a high potential for the removal of cadmium from aqueous solutions.
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İncele - BildiriYalnız künye2005Scopus SJRQ4Effect of temperature for the adsorption of methylene blue onto activated carbon produced from waste dogrose seeds
Gürses, Ahmet; Doǧar, Çetin; Açikyildiz, Metin; Özkan, Esra; Bayrak, Ramis
Activated carbon, produced from dogrose (Rosa section Caninae) seeds, was used for the removal of methylene blue (basic dye). Adsorption studies were carried out at 20°C and 40°C at various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) and at different lengths of time (15, 30, 60, and 120 min). Adsorption isotherms of the basic dye on the prepared adsorbent were determined and correlated with common isotherm equations. Fitting of the isotherm data to the BET adsorption isotherm model was better in high concentration ranges than in the other models. Thermodynamic parameters such as change in isosteric adsorption enthalpy (ΔH)y and isosteric adsorption entropy (ΔS)y were also determined to 40.8 kJ and 0.141 kJ, respectively. It was concluded that the adsorption of methylene blue increases with increasing temperature. BET model fitting indicates that the hydrophobic interactions between the dye and the produced active carbon at the first layer and the dipole-dipole interactions between methylene blue molecules and the adsorbed molecules at the secondary layer predominate. To investigate the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made.
AtıfScopus1OpenAlex1İncele