Study On The Preparation Of Dual-network Graphene Oxide/polyacrylic Acid Framework And The Adsorption Characteristics Of Water Pollutants

Graphene based adsorbents have caught tremendous attentions in sewage treatment.However,due to strong ?-? stack and van der Waals forces between graphene sheets,irreversible agglomeration can easily occur in aqueous solution,which could result in the fact that its actual specific surface area is much lower than the theoretical value,and greatly inhibits the adsorption performance of graphene.Although graphene oxide(GO),as one of the most important derivatives of graphene,has excellent adsorption performance towards pollutants in water,there are a lot of problem in practical applications such as difficulty in separation,toxicity of nanoparticles.In order to solve the above problems,this paper proposed to constructe a three-dimensional(3D)graphene-based adsorbent with high adsorption capacities,fast adsorption rates and excellent adsorption cycles by introducing PAA polymer network structure into GO layers.Further,the structure of the GO/PAA was controlled through adjusting experimental parameters,and the structure-function relationship between the microstructure of GO/PAA and their adsorption properties towards multiple pollutants was investigated.In addition,a series of adsorption models were fitted to explain the relevant adsorption mechanism,which would lay theoretical foundations and experiences for the preparation of graphene-based adsorbents.In this paper,the 3D GO/PAA skeleton composites were successfully constructed from GO and acrylic acid(AA)using in situ solution polymerization method,and the mechanism of action between GO and AA was explored.From the comparison and analysis of micro morphology by SEM,we can clearly see that GO/PAA skeleton materials presented a double network porous structure when the amount of initiator(KPS)and crosslinking agent(MBA)were 1%of the monomer mass,and the mass ratio of GO and AA was 1:7.The change of functional groups could be observed by combining X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FT-IR),and the structures of crystals could be detected through X-ray diffraction(XRD)and Raman spectroscopy.The results showed that the introduction of PAA polymer network increased significantly the layer spacing of the functional GO layer,which inhibited the occurrence of agglomeration between the layers,and provided favorable conditions for construction of 3D skeleton materials.At the same time,GO layers could be assembled into macro structure through hydrogen bonding between PAA polymer network and GO layer.And introducing of PAA increased greatly the carboxyl group content of the as-resulting GO/PAA,which provides a possibility to improve significantly the adsorption performances of GO/PAA towards pollutants.We compared the adsorption performance of prepared aerogels towards cationic dyes(methylene blue,crystal violet,rhodamine B and methyl orange)and heavy metal Cu2+ ions by Ultraviolet spectrophotometer(UV)and Inductively coupled plasma-optical emission spectrometer(ICP-OES).We found that the obtained GO/PAA3 with double network exhibited outstanding adsorption properties towards above five pollutants.In addition,we also explored the change of GO/PAA3 adsorption behaviors under different extermal condition(adsorption time and solution pH value),and the adsorption isotherm and kinetics models were fitted nonlinearly to reveal the interation mechanism between GO/PAA3 and pollutants.