Study On The Preparation Of Graphene Oxide Composite And Adsorption Performances For Pb(?) Ions

This paper briefly introduced the pollution and damage of heavy metal,the application of adsorption method to remove heavy metals and graphene oxide composites in adsorptioa.In this work,Graphite oxide was prepared by modified Hunmmers and then was subjected to ultrasonic treatment in the water to prepare graphene oxide.At room temperature,the graphene oxide was modified by polyethylenimine?PEI?and sodium carboxymethyl cellulose?CMC?via the method of solution blending to synthesize GO/PEI and GO/PEI/CMC composites with different mass ratio.The GO/PEI and GO/PEI/CMC composites were chosen as adsorbents to study and compare their performances for Pb²⁺ adsorptioa?1?Raw graphite was oxidized by the improved Hummers method to prepare graphite oxide,further exfoliated by ultrasound.Its structure and thermal stability were characterized and analyzed by FTIR,Raman,XRD,XPS and TGA/DTG It was found that the oxidation degree of graphite could be improved with the reaction time increasing slightly,but the thermal stability of GO decreasing.?2?At room temperature,GO/PEI composite was obtained via nucleophilic substitution reaction between polyethylenimine and GO.Glutaraldehyde as cross-linker,sodium carboxymethyl cellulose was used to further functionalized GO/PEI to prepare GO/PEI/CMC composite.Their structure,surface topography and thermal stability were characterized by FTIR,Raman,XRD,XPS,SEM and TGA/DTG The results indicated that GO/PEI had layered structure with larger layer spacing and rougher surface than that of GO,while GO/PEI/CMC formed three dimensional structure and its surface was the most rough,from SEM and XRD analysis.XPS analysis showed that the oxygen content of GO/PEI/CMC was clearly higher than that of GO/PEI,as a result of increasing the amount of oxygen-containing groups from CMC.It was revealed that the thermal stability of GO/PEI/CMC was higher than that of GO,GO/PEI.Adsorbent contrast experiments showed that GO/PEI and GO/PEI/CMC composite with mass ratio of 1:3 and 1:2:1 had the best adsorption effects on Pb²⁺.?3?Using GO/PEI and GO/PEI/CMC composite as adsorbent,the adsorption behaviors of GO/PEI and GO/PEI/CMC were investigated with batch experiments,including the effects of adsorbent dosage,initial pH value,adsorption time,initial Lead concentration and temperature.The study showed that the optimal initial pH value of GO/PEI and GO/PEI/CMC were 6.0 and 5.5,respectively,when the mass of adsorbents were both 20mg.The Pb²⁺adsorption reactions on GO/PEI and GO/PEI/CMC reached equilibrium within nearly 120min,200min and the equilibrium adsorption amount were 76.6mg/g,95.4mg/g.Langmuir model and Lagergren pseudo second-kinetics model could better fit the adsorption process of GO/PEI and GO/PEI/CMC for Pb²⁺ adsorption,indicating that the adsorption processes were single-layer coverage and the theoretical maximum adsorption capacities were 277.8mg/g and 384.6mg/g.The adsorption of Pb²⁺ on GO/PEI was controlled by chemical adsorption,whereas GO/PEI/CMC for Pb²⁺ adsorption was dominated by chemical adsoiption and particle diffusion together.Thermodynamic studies revealed that adsorption Pb²⁺ on GO/PEI and GO/PEI/CMC were exothermic and spontaneous.Moreover,after 4 times of repeated use,adsorption capacity varviations of GO/PEI/CMC was less than that of GO/PEI,showing that GO/PEI/CMC had a better recyclable performance.