| Water pollution has become one of the most important environmental and economic problems in the world.Heavy metal pollution in water environment can not be ignored.Therefore,the EU Drinking Water Directive which amended by the European Community in 1995 restricts the concentration limits of heavy metal ions such as Cu(?)and Pb(?)in drinking water.Heavy metal pollution is particularly prominent in the areas where the metal electroplating industry or the mining sites of non-ferrous metals are located.The main methods which used to treat heavy metal pollution problems include ion exchange method,biological treatment,membrane treatment and so on.Due to the advantages of low cost,simple operation and management,short treatment cycle and high treatment efficiency,adsorption plays an irreplaceable role in water pollution control as an effective method to remove heavy metals.Therefore,a unprecedented material were prepared as adsorbents to remove Cu(?)and Pb(?)ions in water in this study in order to provide theoretical basis for its practical application in real water environment for pollution control in the future.Traditional hydrotalcite materials are regarded as adsorbents with good productivity and prospects for environmental remediation due to their adsorption capacity and simple preparation conditions.Hydrotalcite,as a new nano-material,presents a unique layered structure.Because of its unique characteristics,hydrotalcite has become a hot material in adsorption technology research.However,it is necessary to be modified due to its poor stability and easy stacking properties.This is of great significance to the application and development of hydrotalcite in the field of adsorption.The magnetic carbon sphere not only has the advantages of high specific surface area,controllable particle size and pore size,less environmental pollution,but also has the characteristics about magnetic and dispersibility.Carbon-related materials have been widely used in medicine,catalysis,fuel cell and other fields in the past research.There are abundant functional groups in the surface of magnetic carbon spheres,and they also have abundant pore structure.Therefore,in this paper,magnetic carbon/magnesium hydrotalcite nanocomposites(MCs@ Mg/Fe-LDHs)were prepared by chemical coprecipitation using those materials introduced above.Scanning electron microscopy(SEM),transmission electron microscopy(TEM),specific surface area analyzer(BET),X-ray diffraction analyzer(XRD),Fourier transform infrared spectroscopy(FTIR)and potentiometer were used to analyze the physical and chemical properties of the monomers and complexes.At the same time,the adsorption performances and potential adsorption mechanisms of MCs@Mg/Fe-LDHs for contaminants of Cu(?)and Pb(?)ions under various conditions were studied.The effects of adsorption kinetics,adsorption isotherms,solution pH and the existence of other heavy metal ions on the adsorption of Cu(?)and Pb(?)ions were investigated in detail.The results of the study show that MCs@Mg/Fe-LDHs can effectively remove Cu(?)and Pb(?)ions from aqueous solution,and its maximum adsorption capacity can reach 338.70 mg/g and 758.35 mg/g,respectively.And MCs@Mg/Fe-LDHs can selectively remove Cu(?)and Pb(?)ions from the aqueous solution which contains a variety of heavy metal ions.The adsorption mechanisms of MCs@Mg/Fe-LDHs were analyzed and it was found that the multiple factors,such as surface complexation,precipitation,isomorphic substitution,electrostatic attraction and physical adsorption,produced the adsorption results in the experiments.Generally,MCs@Mg/Fe-LDHs has the advantages of good adsorption capability,good stability as well as easy preparation and it is regared as a novel hydrotalcite composite material with great prospect. |
PDF Full Text Request