Study On The Modification Of Graphene And Applied To Adsorption Of Aspirin By The First-principles

In recent years,pharmaceuticals have been detected in water bodies and solid wastes in the world,and it is even more worrying that drugs have also been detected in animals.In the meanwhile,many researchers have found that drugs have entered the ecological environment through many kinds of ways,which means that the environment and human health are facing huge potential risks.So,it is imperative to deal with environmental pollution caused by pharmaceuticals.Among the numerous treatments of drug,the adsorption method is more economical,its effect is remarkable,and the application range of it is extremely wide as well.As for adsorbent materials,graphene and modified graphene have great potential in the treatment of pharmaceutical drugs:it has a large specific surface area,abundant surface functional groups,and it can have a strong?-?electron interaction with drug molecules?having aromatic groups?.Therefore,Graphene has great prospects in the absorption of drug molecules,which has attracted great interest from many researchers.For the past few years,computational materials science has shown irreplaceable features in many studies,with the improvement of computer computing power and the theoretical system of computational chemistry,is playing an increasingly important role in chemical research with its low cost and high efficiency.Based on the density functional theory,four graphene materials were simulated by metal doping,surface modification,surface defects and heterostructures,and the effects of adsorption of aspirin molecules were studied.?1?The adsorption of aspirin molecules over different adsorption sites on the intrinsic graphene and Ti-doped graphene were studied based on the density functional theory.Through the calculation and analysis of adsorption energy,and charge distribution,we found that there is a conjugated large?bond adsorption with a weak interaction force between the intrinsic graphene and the aspirin molecule.Furthermore,for Ti-doped graphene,it has a strong adsorption effect on aspirin molecules owe to the formation of the chemical bonds.Meanwhile,we discovered that there is an electric charge transport channel between O-Ti-C.?2?Based on the primitive graphene model,we built the simulated biochar materials by modifying SH,S,NH₂ and NH groups on the surface.We found that the adsorption of aspirin molecule by the simulated biochar materials was not satisfactory.However,the adsorption became better when a Ti atom was doped into the previous graphene model.A chemical bond was discovered between aspirin molecule and the simulated biochar by calculating the adsorption ability at the different distances between surface groups and dopant atoms.The simulated biochar model is more stable,and the adsorption of aspirin is better.The simulated biochar structure and adsorption ability were significantly influenced by the doping distances.?3?A graphene defect model was constructed on the basis of the primitive graphene.We found that monoatomic-deficient graphene can stably exist which exhibited a surprising big adsorption energy for aspirin with a value of-8.81 eV.By analyzing the electron density of the state further,a chemical absorption was confirmed in the case.Moreover,a charge transport channel was formed between the suspended carbon atom of defect graphene and the carboxyl group of the aspirin.?4?Further,we constructed a heterostructures of graphene and carbon nitride,and the adsorption of heterostructures toward aspirin was studied by building different layer models.Through the investigation of the stability,bonding energy,electronic structure under different conditions,it has shown that the heterogeneous structure with an completely mismatched unit cell is more stable than that with the perfectly matched unit cell,and the ability toward aspirin adsorption is enhanced compared to the case of the only one layer of carbon nitride model.When the graphene layer of the heterostructures was set up to close contact with aspirin,the interaction between the graphene layer and aspirin is more pronounced,resulting in a change in the hetero-structures.