Efficient Clean-up Of Phosphate From Water By Ionic Liquid Functionalized Polyacrylonitrile Fibers

P plays a significant role in agriculture,animal husbandry,phosphorylation industry and our daily life,which is the essential element of life.With the rapid development of agriculture and industry,environmental problems caused by phosphate pollution are becoming increasingly severe.The phosphorus-containing compounds produced by human activity flows into the natural water,leading to excess phosphorus in natural water,which further contributes to a series of environmental problems like eutrophication and poses a serious threat to human health and the balance of ecological environment if it further worsens.Agricultural non-point source pollution is the main source of phosphorus pollution.The enrichment and separation of phosphorus-containing compounds from farmland tail water can prevent phosphorus pollution and recycle non-renewable resource.Based on this,the ionic liquid functionalized fiber（PAN_AF-Cl）was prepared by using the advantages of fiber carrier,and then we explored the effect it had on removal of water phosphorus.We prepared PAN_AF-Cl by two simple steps:amination and acidification and characterized it through a variety of technical means like Fourier transform infrared spectroscopy（FTIR）,X-ray diffraction spectroscopy（XRD）,Elemental analysis（EA）.Adsorption experiment further demonstrated that the PAN_AF-Cl reached the adsorption equilibrium within 5 min,with a maximum phosphate adsorption capacity of 15.49 mg P/g,which showed its high adsorption efficiency.The fiber possessed a wide range of p H adaptability（p H=3～9）with maximum adsorption capacity at the p H value of 5.A pseudo-second-order kinetic model and Langmuir isotherm model could better fit the adsorption of phosphate by the PAN_AF-Cl,which indicated that the adsorption process belonged to monolayer chemisorption.This study also explored the impact that Cl^-,NO₃^-and CO₃^2-etc.coexisting ions had on material adsorption,discovering the PAN_AF-Cl remained considerable phosphate removal ability when coexisting complex ions were included.The prepared ionic liquid functionalized fibers had strong cycling property,could perform absorption-desorption on phosphate and could be used repeatedly for more than five times after being soaked in hydrochloric acid solution with a certain concentration.Then,we studied the phosphate removal efficiency of fibers under the continuous flow conditions.The results showed that the removal rate was as high as above 90%,which indicated fibers could be applied to flowing water bodies and had more advantages in comparison with powder and other materials.What’s more,we explored the practical ability of PAN_AF-Cl in the actual water body.It exhibited a low adsorption limit（0.0184mg P/L）in Chaohu water body,which was lower than water body eutrophication threshold.Meanwhile,the results showed that phosphate removal efficiency of PAN_AF-Cl was as high as 98.8%when it was tested in domestic sewage containing a variety of anions（F^-,Br^-and NO₃^-etc.）.Given all that,as a kind of phosphate adsorbent with a high efficiency,PAN_AF-Cl has potential practical value in terms of farmland tail water,inorganic phosphorus removal of domestic wastewater and natural water bodies and prevention and control of phosphorus pollution in waterbody.