The Study Of Tannin-reduced Graphene Oxide And Its Functionalization By Polyacrylamide

Graphene possesses many superior properties such as excellent electrical,thermal and mechanical performance as well as a large specific surface area.In the laboratory,Hummers method is often used to prepare graphene.While the product is usually called“reduced graphene oxide”?RGO?.After the remove of the oxygen-containing functional groups on the surface of the graphene oxide,the strong interaction between the graphene layers will results in irreversible aggregation.And it will decrease the excellent properties of the graphene.Therefore,finding a way to avoid the aggregation between the graphene layers and functionalize the graphene at the same time will be a problem need to be solved.In this paper,we reported a novel method to functionalize the graphene,which used a green reducer tannin and anionic polyacrylamide?APAM?.First of all,RGO-H and RGO-T were obtained respectively through the reduction of graphene oxide with hydrazine and tannin.The structure of the products were analyzed by FTIR,Raman spectrum and UV absorption spectroscopy.The results prove that graphene oxide is really reduced by hydrazine and tannin.The partical size of the RGO-T increases with the increasing tannin dosage.Because that tannin can connect several graphene layers,which through the interaction between the benzene ring structure in the tannin and the?-conjugated system on the graphene.Methylene blue test adsorption method was used to determine the specific surface area of RGO.The value of RGO-H and RGO-T were 794 and 1192 m²g^-1 respectively.It indicates that tannin can hinder the aggregation between graphene layer and lead to lager specific surface area.We also used water-soluble polymer APAM to functionalize the graphene through flocculation.Firstly,APAM was added in to the aqueous solution of graphene oxide,then the floccule was obtained followed by reduction reaction.The graphene functionalized by APAM were named RGO-H/APAM and RGO-T/APAM,according to the different reducer,hydrazine and tannin.The structure and morphology were also analyzed by FTIR,Raman and TEM.The results indicate that APAM successfully intercalates into the graphene layers and decreases the extent of the aggregation.According the results of methylene blue test adsorption test,we find that RGO/APAM's adsorption capacity of methylene blue molecule is superior to unmodified RGO's.Finally,we studied RGO/APAM's adsorption of Pb???and investigated the effect of pH,temperature and contact time on the adsorption capacity.The results show that the pH of 6 is appropriate and this process will release of heat.Among the RGO-H,RGO-H/APAM and RGO-T/APAM,the adsorption capacity of RGO-T/APAM is the highest and RGO-H's is the lowest.The adsorption equilibrium data of RGO-T/APAM fits well with the Freundlich adsorption model and the adsorption kinetics follows the second-order equation.And RGO-T/APAM's maximum adsorption capacity of Pb???is 147.71 mg/g.