Isotherm Studies of Adsorption of Cr (Vi) Ions onto Coconut Husk

Abstract

In this study, the application of ground coconut husk GCH for removal of Cr (VI) from its aqueous solution was investigated. Several batch experiments were carried out with different values of test conditions including sorbent concentration, contact time, temperature and pH. The results obtained showed that adsorption of Cr (VI) followed Freundlich isotherm model. Dubinin-Radushkevich isotherm revealed that adsorption of the three metal ions principally followed chemical adsorption process. Adsorption kinetics was best described by pseudo-second order. Thermodynamic studies revealed that adsorption of Cr (VI) were endothermic process since ∆H was positive. Adsorption of Cr (VI) was spontaneous as evident from the negative value ∆G. Uptake of metal ion from their aqueous solution increases with increase in pH but decreases slightly at pH of 8.