Adsorption of heavy metal and organic pollutant by organo-montmorillonites in binary-component system

In this study, the adsorption capacity of organo-montmorillonites (OMt) modified with cationic surfactants and chelating reagent toward binary-component, heavy metal and organic pollutant, in aqueous solution was investigated through batch experiments. The characteristics of the OMt were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Specific surface area (BET), respectively, confirming that hexadecyl trimethyl ammonium chloride (CTAC), ethylene diamine tetraacetic acid (EDTA) and 1,6-diaminohexane (DA) were successfully introduced into Na+-Mt. Comparing with stronger Zn2+ removal efficiency onto EDTA-Mt and DA-Mt dominated by forming complexes in the binary-component systems, CTAC–EDTA-Mt and CTAC–DA-Mt gained a huge edge in uptaking phenol controlled by layer partition. Factors containing the initial Zn2+/phenol concentration and the competitive adsorption where the Zn2+, Pb2+, Cd2+ and phenol/Zn2+, p-nitrophenol, phenylamine and phenol coexisted in the aqueous solution were shown in the paper. Furthermore, the desorption of Zn2+ and phenol on the CTAC–DA-Mt was investigated by series experiments under various conditions (with the type of chemical reagents, variable concentration of desorbent and contact time). The results showed HCl solution had higher efficiency on desorbing Zn2+ over phenol onto the CTAC–DA-Mt. CTAC–EDTA-Mt and CTAC–DA-Mt had potential applications in dealing with the wastewater where heavy metals and organic pollutants coexist.