Study On Phosphorus Removal By Inorganic-organic Covalently Bound Hybrid Coagulants

With the rapid development of society and economy,phosphorus pollution in water has been taken into more considerations.Phosphorus pollution is mainly resulted from the discharge of domestic wastewater containing inorganic phosphorus and industrial wastewater containing phosphorus.There are numerous types of inorganic phosphorus and organic phosphorus discharged into the water,and the structures for these materials are complex,which can cause severe threats to the health of human body and the safety of the ecological environment.Chemical phosphorus removal has become the most widely used wastewater removal process because of its high phosphorus removal efficiency and simple process of phosphorus removal.The application of flocculants to remove phosphorus is an important way of chemical phosphorus removal.However,at a molecular level,the process and mechanism of action between flocculants and phosphorus,especially organic phosphorus is undefined.Also,the relationship between the removal efficiency and the phosphorus'structure is not clear.This paper selectes two kinds of conventional flocculants?poly aluminium chloride PAC,polyferric sulfate PFS?and a novel covalently bound inorganic–organic hybrid coagulants?CBHyC?to test the removal effects of phosphate and 7 different structures of organic phosphorus.The results show that the effect of polymerized aluminum chloride?PAC?and polyferric sulfate?PFS?on the removal of partial organic phosphorus is poor,and the removal efficiency to phosphorus us greatly influenced by the water quality conditions?pH,initial phosphorus concentration,humic acid and turbidity,etc.?.What's more,the efficiency of covalently bound hybrid coagulants?CBHyC?for removing inorganic phosphorus and most of the organic phosphorus is more than 98%.Furthermore,covalently bound hybrid coagulants?CBHyC?has a stable effect on phosphorus removal and are less affected by the water quality conditions.From Multi-functional photoelectron spectroscopy?XPS?and molecular dynamics simulation?MD?studies can find that covalently bound hybrid coagulants?CBHyC?mainly remove all kinds of phosphorus by electrostatic attraction and hydrophobic interaction induced by covalent bonding of Fe-Si composite structure and long carbon chain quaternary ammonium structure.In addition,On the basis of the density functional theory?DFT?,the quantitative structure-activity relationship?QSAR?model of organic phosphorus removal efficiency and organic phosphorus structure has been established for the first time.Through the quantitative structure-activity relationship?QSAR?model find that phosphorous atomic charge?Q_P?,energy gap(?E_MO)and hydrogen atoms charge?Q_H⁺?associate with the removal efficiency of organic phosphorus,they can influence the removal efficiency of organic phosphorus from covalently bound hybrid coagulants?CBHyC?by affecting the electronegativity and hydrophobicity of organic phosphorus.By means of statistical standard,internal verification and external validation of the model,application domain characterization,etc.can proved the quantitative structure-activity relationship?QSAR?model has higher goodness of fit,good stability and prediction ability,and it can save the cost of phosphorus removal process and condition optimization.