Research On Shape Control And Application Of Iron Phosphate

This article takes hazardous waste phosphating slag as the starting point for research and explores feasible ways of recycling.Phosphating slag is a harmful by-product of the phosphating industry.The zinc phosphating slag mainly contains iron phosphate,zinc phosphate,and other small amounts of phosphate and impurities.The ferric phosphate can be purified from the phosphating slag by using suitable separation means,and the morphology of the purified ferric phosphate can be modified to obtain sub-micron recrystallized ferric phosphate.Try to use the recrystallized iron phosphate obtained by the hydrothermal process as the cathode material and optical Fenton material of lithium-ion batteries,and find an economically valuable way for the regeneration and utilization of phosphating slag.Through the research and analysis of the phosphating slag components,this article uses a two-step method for purification.First,ammonia complexation is used to remove a large amount of zinc phosphate,screen filtering to remove insoluble large particles of impurities,and then heating and pickling to remove other phosphate impurities.The crudely purified iron phosphate with higher purity is obtained.Afterwards,the morphology of the purified iron phosphate is modified,mainly by means of hydrothermal treatment,under the acidic conditions of high temperature and high pressure,the iron phosphate is decomposed and crystallized again.By controlling the hydrothermal conditions,such as hydrothermal temperature,time,surfactant,solution p H,etc.,iron phosphate with a smaller size can be obtained.Malvern laser particle size analyzer（LPS）,X-ray diffractometer（XRD）,scanning electron microscope（SEM）,thermogravimetric analyzer（TG-DTG）and other characterization methods were used to characterize and analyze the samples.The results show that when the hydrothermal temperature is 160℃,the hydrothermal time is 28h,the CTAB dosage is 0.04g,and the p H of the solution is 0.8,sub-micron iron phosphate can be obtained,with a minimum D10 of 0.163μm;however,there are also micron-sized iron phosphates in the sample.For iron phosphate,the D90 value of micron-sized iron phosphate can be reduced by controlling the reaction time,and the particle size distribution range of iron phosphate can be reduced.Lithium iron phosphate is prepared by using the submicron iron phosphate as the precursor,lithium carbonate is added as the lithium source and glucose as the carbon source,the lithium iron phosphate is prepared by the carbothermal reduction method and the button battery is assembled.The structure of the material was characterized by X-ray diffractometer（XRD）and scanning electron microscope（SEM）,and the electrochemical performance of the material was characterized by the VERTEX.C.EIS electrochemical workstation.Samples with three particle size distribution intervals were selected for comparison,and the electrochemical performance of button batteries prepared from different samples were analyzed.The results show that the samples with particle size distribution of0.272-8.703μm have better electrochemical performance,and the specific capacity for the first charge is 154.1 m Ah·g-1,the first discharge specific capacity is 143.8 m Ah·g-1,which is close to the theoretical specific capacity of lithium iron phosphate.After multiple charge and discharge cycles,there is still a good capacity retention rate,but the ratio is higher under high current density conditions.The capacity decay is obvious.Experiments show that it is feasible to use iron phosphate as the precursor of lithium iron phosphate,but the material itself is derived from the solid waste of phosphating slag,and there are many defects.If you want to apply it to battery materials,More research is needed to improve the key factors such as material morphology,impurity content,particle size,phosphorus and iron ratio.Using submicron iron phosphate as raw material,selecting different carbon sources,and preparing Fe²⁺/C composite materials by carbothermal reduction.The Fe²⁺/C composite material is a source of ferrous iron,and H₂O₂and ultraviolet light are used to construct a Fe²⁺+UV+H₂O₂photo-Fenton system.Rhodamine B dye is used as the degradation object to simulate the organic matter in the printing and dyeing wastewater.To study the degradation effect of the system on Rhodamine B organic dyes,and to study the effects of various components of the system,the initial concentration of Rhodamine B,the dosage of Fe²⁺/C composite materials,the dosage of H₂O₂,and the p H value of the solution on the degradation effect..The experimental results show that when the carbon source is graphite,the product is still iron phosphate,and when the carbon source is glucose,the product is ferrous compounds;when ultraviolet light,Fe²⁺/Ccomposite materials,and H₂O₂are present in the system,the optical Fenton system The degradation activity of the system is the highest;the system has a fast degradation rate for rhodamine B solution with a concentration below 15mg/L,and the degradation effect will decrease when the concentration continues to rise;when the Fe²⁺/C composite material dosage is 2.0g/L When the H₂O₂dosage is small,the degradation efficiency of Rhodamine B increases with the increase of the H₂O₂dosage,until the initial concentration of H₂O₂reaches 15mmol/L,the degradation effect begins to gradually deteriorate.;Comparative analysis of the results of degradation experiments under different p H conditions,the photo-Fenton system has degradation activity in the p H range of 2-5,and it is more conducive to the degradation of Rhodamine B under acidic conditions of p H=3-4;the results show that Under suitable experimental conditions,the photo Fenton system composed of Fe²⁺/C materials can effectively remove rhodamine B dye in the solution,and the degradation effect can reach 100%,which is expected to be a way to solve organic wastewater.