adsorption of copper (ii) ions on a montmorillonite clay and its application as heterogeneous catalyst for knoevenagel condensation reaction

In the present study, a simplest and most effective method was applied to removal of cu^2+ ions from an aqueous solution using montmorillonite clay, nontoxic and abundantly available as an adsorbent. the used adsorbent was characterized using x-ray diffraction (xrd), the x-ray fluorescence spectrometry, fourier transform infrared spectroscopy (ft-ir) and scanning electron microscope (sem) coupled with edx analysis. adsorption experiments were conducted under various conditions,.i.e., contact time , initial concentration, ph of cu(ii) ions solution, adsorbent mass, and particle size . the results proved that the adsorption of cu(ii) ions by montmorillonite clay was favorable at ph=5.5 with an extraction yield of 85% after 30 min contact. the equilibrium isotherm data were analyzed using the langmuir and freundlich equations. in all cases, the adsorption process fitted the second-order kinetics well, and the isotherm equation due to freundlich showed good fits with the experimental data. in order to value our cu-montmorillonite clay (cu-mc) support, we thought of applying it as recyclable heterogeneous catalyst for the condensation of knoevenagel. the model reaction was carried out at room temperature, using a quantity of 0.5 mg of catalyst and a volume of 2ml of ethanol, the reaction yield was excellent (87%). the recyclable solid catalyst was effective for five successive cycles, indicating that this clay is a potentially eco-friendly heterogeneous catalyst.