Research On The Aqueous Adsorption Characteristics And Predictive Model Of Aromatic Contaminants By Graphene Oxide

Graphene oxide(GO),with large specific surface area and strong water solubility and surface paintability,exhibited extraordinary adsorption capability towards organic contaminants.It have attracted great concern in controlling environmental organic pollutants.The control efficiency of organic contamination would directly determined by the adsorption perfomance of GO.Therefore,clarifying the sorptive characteristics,factors and adsorption mechanism during adsorption process are vital to improve the adsorption capacity as well as pollution control efficiency,and thus promote the development and application of GO as a nanoadsorbent.In this work,GO were synthesized by modified hummers method and were utilized to investigate the adsorption properties of ten aromatic contaminants on GO by batch adsorption experiments,and then the quantitative structure-activity relationship(QSAR)methods were employed to establish the prediction relationships between the structural parameters and adsorption capability of aromatic contaminants on GO.The solvation parameters and quantum chemical parameters were calculated to build QSAR model and to explore the adsorption mechanisms and the relative contributions.The results could be beneficial to understand the adsorption characteristics of GO towards organic pollutants,and offer the new outlooks for adsorption capability prediction as well as theoretical basis for environmental risk manangement.One component adsorption of aromatic contaminants were investigated in this paper.The results indicated that GO showed excellent adsorption capacity toward ten aromatic contaminants,the adsorption process was controlled by the mutual effects of various properties of contaminants,covering the number of benzene ring,sorts and numbers of substituents,molecular volume and hydrophobicity,etc.The adsorption equilibrium isotherms of ten aromatic pollutants were fitted by Freudlich model and Langmuir model,which indicated there existed nonlinear sorption process on the GO,the adsorption sites on the GO surface were heterogeneous.There were faster reaction rates during adsorption processes,the adsorption dynamic data on GO were fitted to pseudo-second-order kinetics.The adsorption process of bisphenol A on GO was spontaneous and exothermic,lower temperature would be helpful to adsorption process.Meanwhile,the adsorption capability of aromatic contaminants exhibited different pH dependency due to the charge of GO and the existing species of aromatics under different pH.And the increasing temperatures and introduction of cations would cut down the adsorption capacity of pollutants.To establish the LSER and quantum-chemical QSAR predictive relationships for the adsorption capability of aromatic contaminants on GO,predicting the adsoption capacity and deeply exploring the adsorption mechanisms during the sorption process.The results indicated that both of them possessed better fitting capability,strong robustness and predictability for the new compounds.But the model with quantum chemical method had a better effect as comparision.The LSER model demonstrated that hydrophobic interaction and nonspecific interactions captured by vV and eE interaction term and hydrogen-bond effects captured by bB interaction term were the prominent mechanisms during the adsorption process,which contributed mostly to the adsorption capacity.The quantum-chemical QSAR model exhibited that the main factors governed the adsorption of organic compounds on GO were molar refractivity(MR),distribution coefficient(logD),heat capacity at constant volume(Cv)and the most negative charge of non-hydrogen atoms(Q-),namely,the hydrophobic effects captured by logD,? interaction captured by MR and hydrogen-bond interactions captured by Q-were the three predominant adsorption mechanisms during the sorption process of aromatic contaminants on GO,the results were consistent with the outcomes of experiments and LSER model.