Manganese Silicate Composites Derived From Iron Ore Tailing And Its Selective Adsorption Properties For Cationic Dyes

Iron ore tailing(IOT)is a kind of solid wastes produced during the iron beneficiation process,which have caused serious negative impacts on the environment.There are also hidden safety hazards such as dam breaks in the tailings pond.High-silicon iron ore tailing is one of the largest production iron ore tailing in the Beijing-Tianjin-Hebei region.They are mainly composed of quartz,anorthite,plagioclase,plagioclase and biotite.The silicate composite mineral contain abundant silicon-oxygen tetrahedrons.At present,the focus of iron ore tailing research is on the use of iron ore tailing as a special“chemical raw material”.There was little systematic research on constructing new materials or structural transformations based on the microstructural characteristics of iron ore tailing.Our research uses high-silicon iron tailings as the main raw material to prepare manganese silicate composites,studies the structural transformation of high-silicon iron ore tailing during preparation,and explores the selectivity adsorption capacity and mechanism of manganese silicate composites for methylene blue(MB)in mixed cationic dyes and the aim of“using waste to treat waste”will be achieved.In this paper,Mn²⁺is introduced by a hydrothermal method to react with high-silicon iron ore tailing under alkaline conditions.The obtained manganese silicate composites are mainly composed of Si,O,and Mn elements,and contains a small amount of Al,Mg,and Fe.And surface is rich in Mn-OH groups.The manganese silicate composites with a layered structure of hollow nanobubbles and curled nanosheets were prepared by adjusting the amount of Mn added and experimental conditions,respectively.When the hydrothermal reaction time is 12 hours,the temperature is 180°C,and the added amounts of sodium silicate and Mn²⁺are 4.263 and 3.676 g,respectively,the synthesized composite material has a layered structure of rolled nanosheets,and its specific surface area and pore volume is448 m² g^-1 and 0.729 cm³ g^-1.After calcination at 600°C,the manganese silicate composites achieved a transfromation from amorphous to crystalline.During the synthesis process,OH^-and SiO₃^2-ions produced by the hydrolysis of sodium silicate interact with the surface of silicate composite minerals,and Si-O and M-O(M=Al,Mg,Fe,etc.)chemical bonds in minerals are broken by alkali etching,forming a large number of active sites on the mineral surface,providing adsorption sites for Mn ions;silicate ions and Mn²⁺combine at the solid-liquid interface between the quartz in iron ore tailing and the solution,and Mn gradually replaces Si-O-Si in the silicon tetrahedron.Finally,the newly formed amorphous manganese silicate and unreacted quartz together constitute the manganese silicate composite.The prepared manganese silicate composite has excellent adsorption performance for MB.Under the conditions of this working experiment,the removal rate of the composite material was 99%within 1 minute,and the maximum adsorption capacity was 217 mg g^-1.The adsorption behavior conformed to the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model.The adsorption process included physical adsorption and chemisorption.Manganese silicate composites show efficient and rapid selective adsorption of MB in mixed cationic dyes.Hydrogen bonding and steric hindrance play a key role in MB selective adsorption process.