Adsorptive removal of Cu(II) from aqueous solution using modified rice husk

In this study, the modified rice husk was tested to remove Cu(II) from water. Batch experiments were carried out to evaluate the adsorption characteristics of the modified rice husk for Cu(II) removal from aqueous solutions. The adsorption isotherms, thermodynamic parameters, kinetics, pH effect, and desorbability were examined. The results show that the maximum adsorption capacity of the modified rice husk was approximately 43.5 mg Cu(II)/g absorbent at temperature of 25 °C and at the initial Cu(II) concentration of 400 mg/L and pH 7.0. And the adsorption isotherm data could be well fitted by both Langmuir equation and Freundlich equation. Thermodynamic studies confirmed that the process was spontaneous and endothermic. The adsorbed amounts of Cu(II) tend to increase with the increase of pH. The adsorption kinetic data can be satisfactorily described by either of the power functions and simple Elovich equations. The desorbability of Cu(II) is about 15-20%, and it is relatively difficult for the adsorbed Cu(II) to be desorbed. The relatively low cost and high capabilities of the rice husk make it potentially attractive adsorbent for the removal of Cu(II) from wastewater.