Adsorption Properties Of Graphene Oxide Composite Aerogels For Cd And MB

In recent years,heavy metal pollution and the pollution of printing and dyeing wastewater have been widely concerned at home and abroad,and various types of adsorptive degradation materials are produced.Graphene is widely used as a material having excellent adsorption properties,but is difficult to recover after adsorption and is susceptible to secondary pollution.Therefore,macroscopic graphene materials have been developed.In this study,based on the preparation of a simple reduced graphene oxide aerogel,biochar,montmorillonite and other functional materials were added,and a graphene oxide composite aerogel was successfully prepared.Adsorption screening of various synthetic aerogels was carried out using Cd and MB as targets for adsorption.The selected composite aerogels were used to adsorb Cd and MB,and the adsorption performance and the adsorption cycle effect of the composite aerogel on Cd and MB were studied.Simultaneously,combined with SEM,XRD and other characterization methods to determine the structure of the composite aerogel and the adsorption mechanism of pollutants.The aim is to obtain high-efficiency,environmentally-friendly and low-cost adsorbent materials,and to provide a scientific theoretical basis for the oxidation of graphene oxide aerogels in heavy metal and organic dye pollution.The main conclusions were as follows:(1)Graphene oxide was used as a precursor.Preparation of the gel process,artificial materials biochar and natural materials(montmorillonite and loess)were added.The in-situ self-assembly method was used to successfully prepare graphene oxide composite aerogel.The prepared aerogel has rich functional groups such as C=O,-OH,ordered porous structure and large specific surface area,and can provide a large number of adsorption sites.Excellent mechanical properties,light weight and environmental protection,the density can be as low as 0.0035g/cm~3.After the adsorption of Cd by aerogel,the EDS spectrum increases the Cd element.In the FTIR spectrum,the vibration peaks representing the functional groups C-O,-OH,C=C migrate or disappear,which proves that ion exchange and cation-?interaction occur with Cd.After the adsorption of MB by aerogel,the EDS spectrum increases the S element,and the FTIR map adds the stretching vibration peaks such as C=S and C-N,and the-OH shifts,indicating that the characteristic peak of MB is introduced into the aerogel system.Prove the success of aerogel adsorption of MB.(2)Cd and MB were used as targets for adsorption,the adsorption and screening of various types of aerogels were carried out.Under the premise of ensuring considerable adsorption,the removal rate of pollutants by composite aerogel was measured.Combining the mechanical properties of various composite aerogels,the appropriate aerogel was determined as the adsorption material for subsequent experiments.It was finally determined that Cd and MB were adsorbed separately when the mass ratio of montmorillonite to GO was 1:10 and 2:1,and Cd and MB were adsorbed when the mass ratio of coarse-diameter biochar to GO was 1:2.(3)Screening of adsorption processes of Cd and MB by M-RGO and BC-RGO.The pseudo second-order kinetic model was more effective in fitting the adsorption data.It was indicated that the occurrence of the adsorption reaction is a result of the interaction of physical and chemical adsorption.The kinetic adsorption of Cd and MB by BC-RGO,the correlation coefficient of Elovich and the double constant model also reached about 0.9,indicating that chemisorption and complexation occurred.The results of isothermal adsorption showed that they are more consistent with L-type,indicating that the composite aerogel plays a dominant role in the adsorption of monolayers on Cd and MB adsorption.The maximum theoretical adsorption capacity of M-RGO for Cd and MB reached 370.37 mg/g and 454.55 mg/g,respectively;the maximum theoretical adsorption capacities of BC-RGO for Cd and MB were204.08 mg/g and 370.37 mg/g,respectively.Thermodynamic adsorption experiments show that M-RGO and BC-RGO have the same adsorption results for Cd and MB,and the reactions can be carried out spontaneously,while physical adsorption is dominant,indicating that the porous structure plays a very large role.The adsorption of Cd by the composite aerogel is an exothermic reaction with reduced entropy.The adsorption of MB by the composite aerogel is an endothermic reaction with an increase in entropy.The adsorption of Cd by M-RGO and BC-RGO is enhanced by the increase of pH,which is the result of ion competition and coprecipitation.The aerogel's removal rate of MB showed a trend of increasing and then decreasing.The four adsorption/desorption cycle experiments proved that the adsorption cycles of M-RGO and BC-RGO were good,and the aerogel did not show obvious fracture.The recycling of the successfully prepared composite aerogels M-RGO and BC-RGO can be seen.The aspect has certain advantages.