Research Of Preparation And Adsorption Properties Of Nitrogen-Doped Reduced Graphene Oxide Materials

Clean drinking water is one of the greatest contributions to the human health community.Water is the foundation of life.The protection of water not only improves the quality of human life,but also promotes the progress of the society and the development of the civilization.Therefore,to solve water pollution is one of the top problems in the world today.Accompany era progress,phenolic and oily wastewater discharge increasingly,and threaten human health by years.Phenols and oil belonging to persistent organic pollutants in the wastewater carry high toxicity,easy bio-enrichment,fast migration rate,degradation-resistant and difficult to handle,which is the great challenge in the field of water treatment.Emerging graphene-based water treatment material opens a new door for removing the pollutants from wastewater,due to the excellent physical-chemical properties,functionalization and customizability.In this study,graphene oxide as basic material and chitosan as natural nitrogen source were used to prepared nitrogen doped reduced graphene oxide(N-RGO)via non covalent interaction assembly in the variety layer structure and physical form.We further characterized the morphology and structure of the material,and analyzed the adsorption results and mechanism.The main research contents are listed as follows:1.Chitosan was mainly exfoliated into monomer anchored in the graphene oxide matrix via self-assembly of electrostatic interaction and hydrogen bonding,and obtained N-RGO after thermal annealing treatment.The wrinkles on the surface,pore size and specific surface area of N-RGO material are all increase of annealing temperature and time.Removing oxygen-containing functional groups and recovering sp2 hybridization area enhance the hydrophobic and π-π interactions between N-RGO and phenols.Same time,the introduction of nitrogen atoms avoids the layer stack and improve the performance of dispersed in water environment.The effect of initial pH,pollutants concentration,contact temperature and time on phenol and p-nitrophenol were explored.The adsorption capacity were 155.82 and 80.60 mg/g(pH=6,pollutant concentration＝200 mg/L,contact temperature＝30℃).Furthermore,nitrogen doping enables N-RGO to act as nonmetal catalyst,activating peroxymonosulfate to produce reactive oxygen species such as sulfate radicals and hydroxyl radicals,improving the final removal efficiency of phenols via catalytic oxidation.Finally,the mechanism of adsorption and the synergy between adsorption and catalytic oxidation were expounded.2.Graphene oxide,regarded as an amphiphilic particle for hydrophilic oxygen-containing functional groups and hydrophobic sp2 substrate,and chitosan,as a cross-linking agent,were used to prepare a stable multi-surface graphene network structure via Pickering emulsion templating.And eventually obtained a low density of N-RGO aerogel after annealing.By regulating the oil-water ratio and pH,the emulsion droplet size of the template was affected,changing the total surface area of the graphene network structure.By changing the dosage and proportion of chitosan and graphene oxide,the size and brittleness of N-RGO were affected.Through the analysis of wetting property,N-RGO possessed superhydrophobic and conformed to Cassie-Baxter model.Oil-water separation performance showed that N-RGO absorbed oil phase quickly and possessed self-cleaning function.In subsequent oil absorption experiment,N-RGO absorbed 70 to 113 times of its weight for different oil.