Preparation of Economical and Environmentaly Friendly Modified Clay and Its Application for Copper Removal

Abstract

Copper is toxic and is considered as the hazardous pollutant due to his stability in the environment. Current technologies used for its removal involve materials which can be difficult to synthesize, are expensive or are themselves potentially toxic. Natural clays are abundant worldwide, relatively cheap, possess sorption and ion exchange properties, are candidates as adsorbents. While the Cu(II) sorption capacity of raw bentonite is relatively low, modified bentonites represent a new class of sorbents for effective Cu(II) removal from wastewater. The present study investigates the influence of Algerian clay modification on the capacity of copper removal from water. This montmorillonite, which is a clay mineral of the smectite group, possesses silica tetrahedral sheets layered between alumina octahedral sheets. Several adsorbents were prepared from this bentonite by saturation with sodium, calcium and treatment with sulphuric acid to produce three adsorbents, ARS, ARC and ARH, respectively. The three materials obtained were tested for the Cu(II) adsorption from aqueous solutions. The adsorbents and metal interactions were studied under different conditions of interaction time, pH, concentration of metal ions and amount of clay. It was found that the interactions were dependent on pH, the uptake of pollutant was controlled by the amount of clay and the initial copper concentration. Langmuir and Freundlich models were fitted to experimental isotherms. The Langmuir model shows a better fit to the Cu ions adsorption isotherm for all systems. The largest adsorption capacity is observed for sodium homoionic clay. The Langmuir maximum sorption capacity of Cu(II) ions on ARH, ARC and ARS was found to be 17.241, 18.181 and 24.390 mg/g, respectively. The three adsorbents also showed a high efficiency in the Cu(II) adsorption from much diluted solutions. This work suggested that the modified clays can be promising candidates for the removal of copper ions from aqueous solutions.