Author(s)

Nimibofa Ayawei^1*, Seimokumo Samuel Angaye¹, Donbebe Wankasi^1,2, Ezekiel Dixon Dikio^1,2

¹Department of Chemical Sciences, Niger Delta University, Wilberforce Island, Nigeria.
²Applied Chemistry and Nanoscience Laboratory, Department of Chemistry, Vaal University of Technology, Vanderbijlpark, South Africa.

The adsorption properties of layered double hydroxide (Mg/Al-CO₃) for the removal of Congo Red (CR) dye from aqueous solution were studied. The layered double hydroxide was synthesized by co-precipitation method and characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopic (FTIR) and Energy-Dispersive X-ray Spectroscopic (EDX). The effects of various experimental parameters such as contact time, dye concentrations and temperature variation were investigated. The results show that the amount of Congo Red adsorbed increases with increase in temperature but decreases with increase in initial dye concentration and contact time. The data were also fitted to several kinetic models: zero-order kinetic model, first-order kinetic model, second-order kinetic model, pseudo-second-order kinetic model and third-order kinetic model respectively. The adsorption process was best defined by zero-order-kinetic model (R² = 1). Langmuir, Freundich, Temkin and Dubinin-kaganer-Radushkevich (DPK) adsorption isotherm models were applied to analyze adsorption data with Temkin isotherm being the most applicable to the adsorption process. Thermodynamic parameters e.g. △G^o, △S^o, △H^o and △H_x of the adsorption process were found to be endothermic, spontaneous and feasible.

Congo Red, Layered Double Hydroxides, Kinetic, Dye, Adsorption, Isotherms, Thermodynamics

Ayawei, N. , Angaye, S. , Wankasi, D. and Dikio, E. (2015) Synthesis, Characterization and Application of Mg/Al Layered Double Hydroxide for the Degradation of Congo Red in Aqueous Solution. Open Journal of Physical Chemistry, 5, 56-70. doi: 10.4236/ojpc.2015.53007.