Preparation Of Amorphous Zero Valent Iron For The Degradation Of P-chlorophenol

To tackle the serious issues of environmental pollution,shortage of resources supply and the degradation of ecosystem,China had added the construction of ecological civilization to the 13th Five-Year Plan,and the pollution control methods for water pollution remediation and management had attracted more and more attention.Zero-Valent Iron?ZVI?had become an indispensable part of groundwater restoration,soil remediation and other fields because of its unique chemical catalytic performance.However,the current implementation of the ZVI remediation technology was still facing great challenges,mainly due to the easy oxidation of iron and prone to aggregation,as well as the lack of in-depth theoretical research.In order to solve these difficulties of ZVI technology and to study the degradation mechanism of ZVI to remove organic pollutants,high energy ball milling?HEBM?method was utilized to prepare amorphous ZVI for the degradation of p-chlorophenol.The main research contents included the following:?1?Preparation of amorphous ZVIThe amorphous ZVI was prepared by high energy ball milling method using Fe-based amporhous strips mainly containing Fe and Si.The grain size of amorphous ZVI is 200-250nm and the surface is rough.?2?Analysis of treatment parameters in the reduction and oxidation pathwaysTrichloroethylene?TCE?and methylene blue?MB?were used to study the specific parameters using the amorphous ZVI in the reduction and oxidation pathway,including the initial dosage of the amorphous iron powder,the initial pH of the solution,the initial concentration of H₂O₂.The results showed that the removal efficiency of the system was significantly enhanced under the acidic condition,and the initial concentration of H₂O₂ had a dual effect on the degradation performance.The optimal initial concentration was 60 mM.?3?Effect of amorphous structure on chemical catalytic activity of ZVIThe effect of crystal structure on the electrocatalytic activity of ZVI was studied by comparing the ZVI prepared by the traditional liquid phase reduction method and the crystalline iron powder that was produced by annealing with the amorphous iron powder prepared in this experiment.Amorphous structure has a great influence on the chemical activity and catalytic properties of ZVI.Compared with amorphous ZVI and the annealed crystal ZVI,the former of which has great advantages with higher activity.It could be concluded that the materials prepared by this thesis can improve the oxidation resistance of the samples while maintaining superior chemical activity.?4?Mechanism analysis on the degradation of p-chlorophenolThe degradation mechanism of p-chlorophenol was studied in the presence of amorphous ZVI in the reduction pathway and the oxidative pathway.The degradation process of 4-CP was mainly investigated by density functional theory?DFT?model.The C—Cl of 4-CP was first attacked to form phenol and hydroquinone,which were further transformed to p-benzoquinone and smaller molecule under the oxidation of·OH.?5?Study on the dispersion of amorphous ZVIPoly?acrylic acid??PAA?was introduced in high energy ball milling system during the preparation of amorphous ZVI.The prepared composites exhibited excellent dispersion in aqueous solution.The loading of PAA on ZVI was analyzed by FTIR.The amorphous ZVI with PAA loading exhibited excellent dispersibility and activity,the chemical catalytic activity was improved significantly at 20%loading.