| Sepiolite,for its high surface area and great performance in the adsorption,has been widely used in the treatment of polluted aqueous solution by heavy metals.In this work,sepiolite mineral nanofibers were prepared using microwave chemical technique.The effects of microwave power and microwave heating time on the bulk density were studied systematically.X-ray diffraction?XRD?,Fourier transform infrared spectroscope?FTIR?,scanning electron microscope?SEM?,Zeta potentials were used to characterize the structure and the composition.Furthermore,the performance of the sepiolite mineral nanofibers on adsorption of cadmium ions was studied combined with the effects of initial pH value,dosage of sepiolite mineral nanofibers,initial concentration,temperature and the transport and transfer mechanisms of cadmium ions on the surface of sepiolite mineral nanofibers were mainly studied.The sepiolite mineral nanofibers reach the optimum when the microwave heating time is 13 min and microwave power is 400 W.The bulk density is 0.071 g·cm-3 and the structural stability of sepiolite is kept.The method has a good effect on defibering and removal of pore inclusions.The specific area and the pore volume are increased by 109.21m2·g-1 and 0.234 cc·g-11 respectively.The zeta potentials reach the maximum when the pH value is 5.0.The adsorption capacity of cadmium ions by sepiolite mineral nanofibers can reach 21.49 mg·g-1.The cadmium ions transport and transfer reach equilibrium at the reaction time of 60min.The whole process can be divided into a series of basic processes based on the mechanics of driving force and it complies with the pseudo-second order process and the adsorption regular is described by Langmuir isotherm adsorption model,and the saturated adsorption capacity can reach 21.49 mg·g-1.The diffusion process is an entropy driving process,and the intra-particle diffusion is the rate-determining step.The adsorption process is an endothermic process,mainly controlled by the chemical adsorption. |
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