Research On Controllable Preparation Of Nano-magnetic Functional Materials Based On Iron Tailings Recovery And Selective Adsorption Of Heavy Metal Ion

With the increasing demand for steel,mines are being continuously exploited,leading to a year-on-year increase in the output of iron tailings.As the mining depletes the resources,the value of the remaining iron tailings is gradually being recognized.Iron tailings,as waste after mineral processing,have relatively low metal grade and elemental content,and are largely stockpiled as solid waste.The extensive accumulation of iron tailings not only occupies land and damages the quality of the surrounding land,but it also disrupts local soil structure and groundwater quality,becoming a significant source of environmental pollution.Moreover,it can lead to geological disasters,posing immeasurable threats to people’s lives and property.Secondary recycling and utilization of iron tailings can bring both environmental and economic benefits,hence the rational disposal of iron tailings has become a key issue in reducing environmental pollution pressure and achieving sustainable development in the mining industry.This study aims to achieve the goal of"waste treatment with waste"by preparing environmental remediation materials from valuable elements in iron tailings for environmental protection.In recent years,due to human activities,the content of pollutants such as heavy metals,dyes,and pathogens in the water environment has been increasing.Among them,Pb²⁺has been widely concerned due to its high toxicity,lack of biodegradability,and high abundance.This dissertation analyzes and compares the treatment technologies for heavy metals in the water environment,and adsorption remains the most cost-effective,efficient,convenient,and most suitable method for industrial applications.Among all the adsorbents studied,magnetic nanomaterials have greatly developed due to the dual attributes of magnetic materials and nanomaterials.Based on the above background,this study recycles iron tailings to prepare magnetic nano-functional materials for the adsorption and removal of Pb²⁺.The specific work is as follows:（1）This dissertation first analyzes the elements in iron tailings.Silicon content is the highest,followed by iron.Therefore,the most abundant elements,silicon and iron,are utilized in this study.Fe₃O₄ magnetic nanoparticles are prepared by acid leaching to obtain Fe³⁺solution,followed by the addition of a reducing agent.A series of characterizations prove the magnetic nanostructure of Fe₃O₄.After elemental analysis of the acid leached residue,it is found that iron has been efficiently recycled.By alkali fusion,the acid leach residue is mixed with alkali and baked at high temperature,then fully stirred in an aqueous solution to obtain a silicon leachate.（2）Based on the concept of sustainable development and the utilization of solid waste resources,this dissertation combines bio-based material cellulose with Fe₃O₄ particles to obtain functional magnetic nanomaterials.To improve the selective adsorption efficiency of the adsorbent for Pb²⁺,an ion-imprinted adsorbent is prepared using ion imprinting technology.Adsorption experiments show that the adsorption speed,efficiency,selective adsorption performance,and desorption regeneration performance are all superior after ion imprinting.The adsorption mechanism of Pb²⁺is studied in combination with XPS characterization analysis and experimental results,which include van der Waals forces,ion exchange,and chemical bond complexation.（3）Iron and silicon sources extracted from iron tailings are comprehensively used to prepare molecular sieves and magnetic molecular sieves.XRD characterization analysis shows that the magnetic Fe₃O₄has been fully incorporated,and the hexagonal ordered pore structure of MCM-41 and the MFI topological structure of ZSM-5 have been successfully prepared.However,only amorphous silica structures have been formed for SBA-15 and SBA-16.FTIR characterization shows that the template in the material has been successfully burned off during the calcination process,and the basic structure of the material has been formed.SEM characterization reveals that each mesoporous molecular sieve has formed a loose porous structure,and the specific surface area of each material can reach more than300 m²/g.After the addition of Fe₃O₄,the specific surface area and total pore volume relatively decrease.