Adsorption mechanism of Cu2+ from aqueous solution by chitosan-coated magnetic nanoparticles modified with alpha-ketoglutaric acid.

In order to better understand the adsorption mechanism of chitosan-coated magnetic nanoparticles modified with alpha-ketoglutaric acid (alpha-KA-CCMNPs), the removal of Cu(2+) by alpha-KA-CCMNPs from aqueous solution was investigated in a batch system at 18, 35 and 50 degrees C. Different experimental approaches were applied to show mechanistic aspects, such as adsorption isotherms, kinetics and thermodynamics studies. Adsorption equilibrium studies showed that Cu(2+) adsorption followed Langmuir model. The kinetics of the interactions was best described by pseudo-second-order mechanism. The thermodynamic parameters (DeltaG degrees, DeltaH degrees and DeltaS degrees) analysis predicted that the adsorption process was strongly dependent on temperature of medium, and spontaneous and endothermic process. The XPS combined with FT-IR spectra revealed that N atom of -NH- group and O atom of carboxyl group in alpha-KA-CCMNPs coordinated with Cu(2+). Experimental results from this study provide data that would be required if this heavy metal adsorption system was to be "scaled up" for industrial application.