Adsorption of Indigo Carmine from Aqueous Solution by Chitosan and Chitosan/Activated Carbon Composite: Kinetics, Isotherms and Thermodynamics Studies

• Published in: Fibers and polymers Vol. 20; no. 9; pp. 1820 - 1832
• Main Authors: Fatombi, Jacques K., Idohou, Esta A., Osseni, Sèmiyou A., Agani, Ignace, Neumeyer, David, Verelst, Marc, Mauricot, Robert, Aminou, Taofiki
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Fiber Society 01-09-2019; Springer Nature B.V; 한국섬유공학회
• Subjects: Activated carbon; Adsorption; Aqueous solutions; Chemistry; Chemistry and Materials Science; Chitosan; Endothermic reactions; Enthalpy; Gibbs free energy; Indigo; Isotherms; Mathematical models; Parameters; Peanuts; Point charge; Polymer Sciences; Size distribution; Thermal analysis; 섬유공학; Thermodynamics; Kinetics; Adsorption; Indigo carmine; Chitosan/Activated carbon composite
• ISSN: 1229-9197; 1875-0052
• DOI: 10.1007/s12221-019-1107-y

Activated carbon (AC) obtained from peanut shell, chitosan (CH) obtained from crab shell, and prepared chitosan/ activated carbon (CH/AC) composite were studied in a batch system for the adsorption of indigo carmine (IC) from aqueous solution. Characterizations of AC, CH, and CH/AC were investigated by FTIR, SEM, XRD, zero-point charge pHpzc, thermal analysis, surface area BET, and pore-size distribution. Adsorbent weight (0.01–0.1 g), initial pH solution (2–10), initial indigo carmine concentration (10–50 mg/l) and contact time (0–60 min) were used as parameters in the adsorption equilibrium experiments. Pseudo-second-order kinetic model was found to describe the adsorption process better than pseudo-first-order kinetic model. Langmuir, Freundlich, and Temkin isotherms applied to the adsorption data reveal that AC and CH/AC best fitted Langmuir and Freundlich models when CH data fitted Temkin model with maximum adsorption capacities of 82.64 mg/g for AC, 96.15 mg/g for CH, and 208.33 mg/g for CH/AC at 30 °C. Thermodynamic parameters such as standard Gibbs free energy (Δ
G
°), standard enthalpy (Δ
H
°), and standard entropy (Δ
S
°) were -23.42 kJ/mol, 10.66 kJ/mol, and 112.40 J/K/mol, respectively for CH/AC. The negative value of Δ
G
° and a positive value of Δ
H
° indicate that the removal of indigo carmine by CH/AC is spontaneous and an endothermic process.