Preparation Of Prussian Blue Analogues/ Derivative Catalysts And Application For Bisphenol A Degradation

Water scarcity and pollution are serious to human health and economic development over the world.Therefore,the efficient restoration of wastewater has become one of the most significant topics in the field of water environment.The sulfate radical(SR-AOPs)advanced oxidation processes have been widely used for the treatment of organic micro-pollutants with highly toxic and difficult-to-biodegradable.The activator of Permonosulfate(PMS)can be activated by light,electricity,ultrasound energy,catalysts,etc..Considering the high energy consumption of external energy,and the secondary pollution of metal ions in homogeneous catalysis,it is necessary to develop a high performance and environmentally friendly heterogeneous catalysts.However,there are still many challenges when applied the heterogeneous catalyst,included:(1)The composition and structure of the catalyst are difficult to control,and the preparation process is complicated with low repeatability;(2)The stability of the catalyst,included the leaching of metal ions and the reuse of the catalyst;(3)The structure-activity relationship between catalyst and pollutant degradation is not clear.In this dissertation,the Fe and Co Prussian blue analogues(Fe Co-PBAs)were used as the research objectives,the highly active PBAs-based catalysts were prepared through innovative synthesis methods;Optimizing the structure and components of the catalyst to improve the active sites of the catalysts for BPA degradation;Formulating highly active and environmentally friendly catalysts to improve the degradation efficiency of pollutant.The main research works are as follows:(1)The core-shell Fe Co-PBAs nanocage with heterogeneous composition was prepared based on reducing cation exchange(RCE)strategy.The structural evolution of catalysts were studied by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The three-dimensional structure of PBAs-5 was determined by electronic tomography(ET)and3D reconstruction techniques.Inductively coupled plasma(ICP)was used to analyze the evolution of the composition of Fe and Co elements,and energy dispersive X-ray spectroscopy(EDX)was used to verify the heterogeneous composition of Fe and Co,that is,the shell is iron-rich,the core is cobalt-rich.The reducing cation exchange(RCE)mechanism was proposed.Moreover,this RCE mechanism could be used for the preparation of Fe Mn-PBAs.(2)The RCE strategy is further adopted,the PBAs with various structures can be prepared by adjusting the dosage of cobalt nitrate,Fe Co-PBAs with a variety of specific structures were prepared,including:concave structure PBAs(CCPs),core-shell structure PBAs(CSPs)and polyhedral cubic structure PBAs(PCPs).The Fe Co-PBAs with cubic stack structure was prepared by self-assembly in hydrothermal process.The cyanide bond of potassium cobalt cyanide(III)is used as the ligand,Fe(III)and Co(III)are the metal centers.(Fe-Co)Se₂ catalyst was obtained through selenization reaction of the Fe Co-PBAs.These catalysts are used as to activate PMS to evaluate the degradation of bisphenol A(BPA).The CSPs exhibit excellent BPA degradation.The ICP shows that CSPs catalysts can effectively inhibit the leaching of Co ions due to the protection of the Fe shell(After the catalytic reaction(100 mg/L CSPs)is completed,the leaching concentration of Co ion is 0.14 mg/L).Electron paramagnetic resonance(EPR)and free radical quenching experiments verify that the main reactive oxygen species were SO₄^·-and^·OH.(3)The Fe Co-PBAs@PDA precursor was synthesized by introducing polydopamine(PDA)as a coating polymer.The yolk-shell Fe Co@NC nanoreactor with high specific surface area,porosity and high nitrogen content was prepared by high temperature space-confined pyrolysis.Interestingly,the PDA-derived carbon shell formed preferentially via pyrolysis is of relevance to(i)protecting the framework structure from collapsing,(ii)increasing the specific surface areas and pore volumes,(iii)facilitating the adsorption of pollutants,and(iv)solving the metal leaching problem.The resulting Fe Co@NC nanoreactor exhibits excellent peroxomonosulfate(PMS)activation to degrade BPA(removing 98%of BPA in 5 mins).First-principles calculations indicate that the charge density redistribution becomes much more pronounced when adsorbed on nitrogen-doped graphene with the compressive strain,which leads to a higher density of active sites exposed.The radicals and non-radical processes were confirmed to be simultaneously responsible for BPA degradation.It expands the design ideas for the preparation of efficient and environmentally friendly PBAs catalysts for water environment restoration(After the catalytic reaction(100 mg/L Fe Co@NC)is completed,the leaching concentration of Co ion is 0.058 mg/L).In this dissertation,the formation mechanism of PBAs,the relationship between catalyst components,structure and BPA degradation performance was comprehensively investigated,which provided new ideas for the design of environmentally friendly catalysts.