Adsorption Properties For Chromium Removal Of Graphene Oxide/Iron And Graphene Oxide/Chitosan Miscospheres

Cr???has been commonly used in a number of industrial processes,such as leather tanning,electroplating,mining and printing and dyeing.Due to its high toxicity and bioaccumulation,the removal of Cr???from contaminated aqueous solution is of great importance.In this paper,graphene oxide?GO?was prepared using the Hummers mothed.The adsorption behaviors of Cr???in aqueous solution on graphene oxide/iron?GO-Iron?and graphene oxide/chitosan?GOCS?were systematically investigated.The results are follows:?1?GO was synthesized by graphite powder based on the Hummers mothed and GOIron was prepared then.They were characterized and analyzed by fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,transmission electron microscope?TEM?,and zeta-potential.The results indicate that the oxidation process was perfect and there are plenty of oxygen atoms on the graphitic backbone of GO in the forms of epoxy,hydroxyl,and carboxyl groups,while there were plenty of Fe-O on the surface of GO-Iron.GO was well dispersed in water after 30 min of ultrasound.The zeta-potential of GO was under zero,thus that of GO-Iron was above zero.?2?Study on the factors?such as pH,initial concentrations,contact time,dosage?affecting the adsorption behavior of Cr???on GO-Iron.The kinetics modeling and equilibrium isotherm modeling were analysed and discussed.The results indicated that when the concentrations of FeCl₂ was 0.5mol/L,the obtained GO-Iron had the largest adsorption capacity to Cr???.The optimum condition was as following: the pH was 5.0,the contact time was 180 min,the dosage of GO was 0.5g/L,the initial concentrations of Cr???was 40mg/L.Under the optimum condition,the maximum adsorption capacity of Cr???on GO-Iron was about 31.24mg/g.Kinetics data and adsorption isotherm were better fitted by pseudo-second-order kinetic model and Langmuir isotherm,respectively.?3?The GOCS miscospheres were synthesized and investigated by FTIR and SEM.Study the adsorption behavior of Cr???.The results indicated that the GOCS miscospheres had the largest adsorption capacity for Cr???with the mass ratio of GO and CS was 0.1:4.The adsorption of Cr???onto GOCS miscospheres was optimum at a large pH 3.0⁵.0 at about 180 min.When the initial concentrations of Cr???was 500mg/L,the maximum adsorption ability of GOCS reached at 197.6 mg/g while that of CS reached at 129.9 mg/g.GOCS miscospheres can be used repeatedly.Kinetics data and adsorption isotherm were better fitted by pseudo-second-order kinetic model and Langmuir isotherm,respectively.