Liquid phase adsorption of Congo red dye on functionalized corn cobs

ABSTRACT

This study investigates the adsorption of Congo red (CR) dye onto corn cob based activated carbon (CCAC) in the batch process. The activated carbon was characterized using FTIR, SEM, and EDX techniques, respectively. The effect of operational parameters such as the initial dye concentration (10–50 mg/L), contact time (5–160 minutes), and solution temperature (30–50°C) were studied. The amount of the CR dye adsorbed was found to increase as these operational parameters increased. Kinetic data for CR dye adsorption onto CCAC were best represented by the pseudo second-order kinetic model. Four different isotherms namely Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were used to test the adsorption data. It fitted the Langmuir isotherm model most. Thermodynamic parameters such as ΔH⁰, ΔS⁰, and ΔG⁰ were evaluated. The adsorption process was found to be exothermic and spontaneous. The study shows that CCAC is an effective adsorbent for the adsorption of CR dye from aqueous solution.

GRAPHICAL ABSTRACT

KEYWORDS:

• Adsorption
• Congo red
• corn cob based activated carbon (CCAC)
• kinetics
• thermodynamics

Acknowledgments

The corresponding author acknowledges the support obtained from The World Academy of Science (TWAS) in form of grants; Research Grant number: 11–249 RG/CHE/AF/AC_1_UNESCO FR: 3240262674 (2012) and 15–181 RG/CHE/AF/AC_1_: 3240287083 (2015) respectively.