Study On The Adsorption Properties Of Magnetic Muti-Walled Carbon Nanotubes

In recent years,carbon nanotubes were applied to purify pollutants in the water environment for its excellent adsorption properties.However,increasing concern for its nano toxic effect has led to a growth of special interest in separating nanotubes from water.In this study,MMWCNTs was synthesized by a simple chemical coprecipitation procedure and used to adsorb pollutants in simulation and actual wastewater.The following results are obtained:(1)A variety of techniques such as scanning electron microscope(SEM),transmission eletron microscope(TEM),X-ray diffractometer(XRD),BET surface area measurements,FT-IR spectrum,Raman spectrum and magnetization measurements were used to characterize the structure,morphology and magnetic properties of the prepared composite adsorbents.The static adsorption experiments were measured to investigate the adsorption effects of the prepared adsorbents.The results showed that the composites had good magnetic properties,which allowed their convenient magnetic separation from water.The magnetic nanoparticles was MnFe2O4 and loaded on the surface of the carbon nanotubes by covalent.It was about 10 nm wih negative charge.The presence of magnetic particles didn't significantly affect the surface area and pore structure of the carbon nanotubes.MMWCNTs had more excellent adsorptive properties than before.(2)MMWCNTs were used in the adsorptive removal of tetracycline(TC).The results showed that Pesudo-second order kinetics model was more applicable for the adsorption.Langmuir model was more suitable for the adsorption and the maximal adsorption capacity achieved 256.3 mg/g at room temperature.Thermodynamics indicated that it was a spontaneous,endothermic and physical adsorption.Regeneration experiment results showed that MMWCNTs could be well reused by dealing with alkality.Finally,adsorption model of TC removal rate was builded via response surface methodology(RSM).TC removal rate of RSM model was 97.4%,and the measured values was 96.9% when the adsorbent dosage was 200 mg/L,adsorption time was 480 min and the pH value was 5.12.The forecast deviation was 0.49%.RSM model had a good prediction of TC removal within the rang of design.(3)MMWCNTs were used in the adsorptive removal of copper ionss.The results showed that Pesudo-second order kinetics model was more applicable for the adsorption.Freundlich model was more suitable for the adsorption and the maximal adsorption capacity achieved 3.5 mg/g at room temperature.Thermodynamics indicated that it was a spontaneous,endothermic and physical adsorption.Finally,adsorption model of TC removal rate was builded via response surface methodology(RSM).TC removal rate of RSM model was 73.5%,and the measured values was 71.5% when the adsorbent dosage was 600 mg/L,adsorption time was 90 min and the pH value was 5.0.The forecast deviation was 2.04%.RSM model had a good prediction of copper irons removal within the rang of design.In a word,MMWCNTs not only kept its good adsorption performance,but also had good magnetic separation performance.The research was very significant and its application was broad.