Kinetic, equilibrium and thermodynamic studies on the adsorption of Crystal Violet dye from Aqueous Solution using Activated Cowpea (Vigna Unguiculata) Husk

Abstract

Adsorption of crystal violet dye from aqueous media by activated cowpea husk (ACPH) was investigated using a batch system under controlled conditions. The activated cowpea husk (ACPH) was characterized by Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) methods. The kinetic data were best described by pseudo-second order in all the models studied. Adsorption parameters such as effect of pH, contact time, adsorbent dosage and initial concentration were studied for optimization purposes. The adsorption isotherm for the processes was also estimated and established. The adsorption data fitted well the Freundlich isotherm model relative to other models tested. It was estimated through this study that the adsorption rate is positively affected by increasing ACPH’s relative quantity, adsorbent concentration, time, acidity and temperature. The adsorption equilibrium was shifted toward higher adsorption capacity by the substrate concentration, temperature and acidity. Thermodynamics of the adsorption process indicates the process to be feasible and spontaneous. This indicates that activated carbon produced from cowpea husk can be a promising adsorbent for the removal of hazardous dye from wastewater.