Preparation Of Organo-functionalized Chrysotile Nanotubes And Their Adsorption Of Heavy Metal Ions

In this work, ChNTs-SH and ChNTs-NH2 were prepared by grafting 3-mercaptopropyltrimethoxysilane and 3-ammoniapropyltrimethoxysilane to ChNTs and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption-desorption. And then studied its adsorption properties for heavy metal ions.(1) The characterization results indicated that the thiol and amino were success-fully loaded onto the surface of ChNTs. The structure of ChNTs had no obvious change in ChNTs-SH and ChNTs-NH2. But affected by the functional groups, the order degree, specific surface area, pore size and pore volume of ChNTs-SH and ChNTs-NH2 were declined compared with ChNTs.(2) ChNTs-SH as adsorbent, investigating systematically their Pb(Ⅱ), Cd(Ⅱ) adsorption properties in aqueous solution. The adsorption was mainly affected by pH and temperature. The pseudo-second-order model was more suitable for the adsorption process and the Langmuir model could better simulate the adsorption isotherm data. The adsorption process on ChNTs-SH was a spontaneous and endothermic process. Adsorption process included adsorption of heavy metals on ChNTs and complexation of surface thiol functional group with heavy metal. The ChNTs-SH adsorbing Pb(Ⅱ), Cd(Ⅱ) and Cr(Ⅲ) had a selective adsorption, and the adsorption order was Pb(Ⅱ)>Cd(Ⅱ)> Cr(Ⅲ).(3) The adsorption of Pb(Ⅱ) on ChNTs-NH2 was mainly affected by pH and temperature. The pseudo-second-order model was more suitable for the adsorption process, the Langmuir model could better simulate the adsorption isotherm data. The adsorption process on ChNTS-NH2 was spontaneous endothermic process. Adsorption process included adsorption of heavy metals on ChNTsand complexation of surface amino functional group with heavy metal. The ChNTs-NH2 adsorbing Pb(Ⅱ), Cd(Ⅱ) and Cr(Ⅲ) had a selective adsorption, and the adsorption order was Pb(Ⅱ)>Cd(Ⅱ)>Cr(Ⅲ).