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Chromium(VI) removal by bone char–ZnO composite: Parameters optimization by response surface methodology and modeling
Author(s) -
Ranjbar Neda,
Hashemi Seyedenayat,
Ramavandi Bahman,
Ravanipour Masomeh
Publication year - 2018
Publication title -
environmental progress and sustainable energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.495
H-Index - 66
eISSN - 1944-7450
pISSN - 1944-7442
DOI - 10.1002/ep.12854
Subject(s) - chromium , char , desorption , adsorption , aqueous solution , nuclear chemistry , composite number , distilled water , langmuir adsorption model , specific surface area , response surface methodology , hexavalent chromium , materials science , chemical engineering , nitric acid , kinetics , chemistry , langmuir , chromatography , inorganic chemistry , metallurgy , composite material , pyrolysis , organic chemistry , catalysis , physics , quantum mechanics , engineering
This study presents the efficiency of bone char‐ –ZnO for eliminating chromium(VI) from aqueous solutions. The bone char‐ –ZnO composite was provided using sol‐–gel method. The elemental, morphology, surface analysis of bone char‐ –ZnO were fully studied. The prepared composite was mostly composed of Ca 5 (PO 4 ) 3 OH and had a specific surface area of 28.09 m 2 /g. Results indicated that central composite design (CCD) has a desirable abilit y (R 2 > 0.87) to predict chromium(VI) removal by bone char‐ –ZnO. Furthermore, the results suggest that the removal efficiency increased with the elevation of adsorbent dose, shaking rate, temperature, and contact time. Isotherm and kinetics investigation indicated that chromium adsorption process follows Langmuir mode l (R 2 > 0.97 a nd Q m = 84.03 mg/g) and second‐ order kinetic mode l (R 2 > 0.999). The values o f ΔH ° an d ΔS ° of the chromium adsorption reaction by bone char‐ –ZnO were obtained as 580 kJ/mol and 5.5 kJ/mol K, respectively, suggesting spontaneity and endothermicity of the reaction. Desorption study was also performed by two desorbent agents of distilled water and nitric acid. Overall, it can be concluded that the bone char‐ –ZnO composite is an efficient and potential adsorbent to be used in water and wastewater treatment plan ts. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1684–1695, 2018