Removal of cobalt(II) ion from aqueous solution by chitosan–montmorillonite

Montmorillonite (MMT) modified with chitosan (CTS, molecular weight = 5 × 104) was applied to remove heavy metal cations by using Co2 + as a model ion. An increase in MMT interlayer distance observed from X-ray diffraction indicates the intercalation of CTS into MMT. Together with the results of scanning electron microscopy and Fourier transform infrared spectroscopy, it was concluded that the composite material of CTS and MMT (CTS–MMT) was prepared successfully. The mass ratio of CTS to MMT had a strong influence on the adsorption performance of CTS–MMT. The highest adsorption value of 150 mg/g was obtained over the composite material with CTS to MMT mass ratio of 0.25, which is much higher than those reported in other studies. The adsorption isotherms and kinetic results indicated that Co2 + was adsorbed over CTS–MMT in a multilayer model, and the chemical sorption of Co2 + was determined to be the rate-limiting step.