Study On The Performance Of Fiber Loaded Zero-valent Iron Activated Persulfate To Degrade Organic Phosphorus In Water

The widespread use of phosphorus resources has led to the entry of large amounts of phosphorus into water bodies,inducing eutrophication of water bodies and thus threatening human survival and safety.However,researchers have focused on phosphorus pollution control by removing inorganic phosphorus from water bodies,and there is a lack of research on organic phosphorus from the perspective of nutrient resource recycling.Organic phosphorus is an important component of phosphorus in water bodies,and even in some water bodies,organic phosphorus is the main form,but also one of the main sources of inorganic phosphorus in water bodies,seriously endangering water safety.Therefore,the removal and recycling of organic phosphorus from water bodies is of great significance to control water pollution and relieve the pressure on phosphorus resources.Based on this,this thesis constructs a Fe⁰loaded fiber material to degrade organic phosphorus to inorganic phosphorus by using Fe⁰activated peroxodisulfate（PDS）and to recover the generated inorganic phosphorus simultaneously.The main research and experimental results are as follows:In this thesis,aminated acrylic fibers（PAN_AF）were prepared by hydrothermal method using acrylic fibers as a carrier,and further functionalized fibers（PAN_AF-Fe⁰）with Fe⁰loading were prepared by liquid-phase reduction method,and the successful preparation of fibers was demonstrated by infrared spectroscopy（FTIR）and X-ray diffraction（XRD）characterization.Taking phenylphosphonic acid（PPOA）as an example,the results showed that the Fe⁰sequestration increased the degradation ability of the fiber to organophosphorus,with 99%degradation rate of PPOA(2 mg P L^-1).In addition,PAN_AF-Fe⁰has a wide p H application range（3-9）with 66%-99%degradation;the order of interference of coexisting ions on the degradation of PPOA is HCO₃^->Cl^->NO₃^-,and the degradation rate of PPOA in the presence of NO₃^-can still reach 84%;the degradation effect decreases significantly after the 4th cycle is carried out,and the degradation rate is62.1%;It is worth mentioning that PAN_AF-Fe⁰can also degrade other kinds of organic phosphorus,and the degradation rates of disodium 4-nitrophenyl phosphate,sodium benzene phosphate and sodium phenylphosphonate can reach more than 99%,which indicates that PAN_AF-Fe⁰has good practical application value.The appearance of phenol to its final disappearance was found by liquid chromatography observation of degradation products at different times,indicating that phenol is an intermediate product of PPOA degradation,which is further degraded to carbon dioxide and water;and phosphate products are produced.This thesis further investigated the phosphate removal performance of PAN_AF-Fe⁰.PAN_AF-Fe⁰showed excellent phosphate removal in the p H range of 5-7,reaching an adsorption capacity of 4.78 mg P L^-1at p H=5.The adsorption kinetics and isotherm data were applied to the proposed secondary kinetic model and Langmuir isotherm model,respectively,indicating that the adsorption process is a chemisorption process of a single molecular layer.The XPS results demonstrate that the phosphate adsorption by PAN_AF-Fe⁰is mainly dependent on the coordination reaction between Fe-P and the synergistic effect of protonated amines.However,no phosphate was detected during the degradation process,so it can be concluded that phosphate produced during the degradation of organic phosphorus was removed by simultaneous adsorption.In summary,this study prepares an iron-based fiber material for the degradation and recycling of organic phosphorus.PAN_AF-Fe⁰has the advantages of both efficient degradation of organic phosphorus and simultaneous removal of inorganic phosphorus,effective avoidance of secondary pollution of water bodies by phosphate products after catalytic degradation,and subsequent recycling of phosphorus resources by desorption.It provides a theoretical basis for the recycling of organic phosphorus in water bodies.