Preparation Of Fe-Mn Oxide Composite Aluminosilicate Mineral Material And Its Tl(Ⅰ)Removal

Thallium(Tl)is a highly toxic heavy metal with lithophilic and sulfurophilic properties.It is widely found in metallic or nonmetallic minerals and can be introduced into the environment through metal smelting,fossil fuel combustion and cement production.At present,the reported methods to remove thallium from water mainly include adsorption,chemical precipitation,ion exchange and microbial methods to treat heavy metals in wastewater.The adsorption materials with large adsorption capacity and fast and friendly environment are the key.Active aluminosilicate mineral materials have multiple functions such as ion exchange adsorption,complexation and co-precipitation in the removal of heavy metals from water.They can effectively solidify heavy metals,and are environmentally friendly and not easy to cause secondary pollution.Fe-Mn binary oxides have rich pore structure and large specific surface area,which can significantly improve the adsorption performance of the materials In this study,but the release of Mn(II),it is easy to produce secondary pollution and must be fixed on the matrix material.The two compounds were used to obtain a better thallium removal effect.Two Fe-Mn binary oxides composite active aluminosilicate minerals(FMAAM)were prepared by coprecipitation and hydrothermalmethod.They were FMAAM(1),FMAAM(2).The surface morphology and composition elements of two FMAAM and AAM were analyzed by SEM-EDX.By using BET,the specific surface area,average pore size and total pore volume of the three materials were also analyzed.Two kinds of FMAAM were used to remove thallium from aqueous solution to investigate the effect of adsorbent dose,initial p H and ionic strength on adsorption process.Dynamic models and isothermal adsorption models were used to evaluate the process of FMAAM adsorption of thallium.The mechanisms of FMAAM removal of thallium were explored by means of EDX,FTIR,XPS characterization.The results show that:(1)The SEM analysis shows that the surface of the two FMAAM is rough and accumulates a large number of fine particles,while the AAM surface is relatively smooth.These fine particles are preliminarily judged as iron and manganese oxides,indicating that they are successfully loaded.Using the EDX analysis,compared with the AAM,the EDX analysis diagram of FMAAM shows the peaks of Fe and Mn,which further confirms the existence of iron and manganese oxides on the surface of FMAAM.BET test shows that FMAAM(2)has mesoporous structure and their specific surface area order are:FMAAM(2)(73.41m~2/g)>FMAAM(1)(36.83m~2/g)>AAM(0.1651m~2/g).The specific surface of FMAAM(1)and FMAAM(2)is much higher than that of AAM,both FMAAM exhibit better physical properties.(2)When the adsorbent dose is 1g/L and the initial p H of the solution is 7,the removal efficiency of Tl(I)by FMAAM and FMAAM reached more than 92%and93%,respectively.The removal efficiency of Tl(I)by two FMAAM is good in a wide range.The presence of Na~+has a significant effect on the two FMAAM removal Tl(I)at higher ionic strength.The adsorption process of the two FMAAM to Tl(I)can be fitted well with the pseudo-second-order kinetic model.The adsorption isotherm of the FMAAM(1)is more consistent with the Langmuir model,and its maximum adsorption capacity is 61.50mg/g,while the adsorption process of FMAAM(2)to Tl(I)is more consistent with the Freundlich model,and its maximum adsorption capacity is78.06mg/g.The maximum adsorption capacity of FMAAM was higher than that of AAM(14.28mg/L).Elevating temperature is beneficial to FMAAM(1)adsorption of Tl(I)and the high temperature is not conducive to FMAAM(2)adsorption Tl(I).(3)Through EDX,FTIR,XPS analysis,the mechanisms of adsorption Tl(I)of the two FMAAM in aqueous solution are mainly ion exchange,oxidative precipitation and surface complexation.In summary,the two FMAAM materials prepared in this study have the characteristics of fast adsorption speed and large adsorption capacity for Tl(I)removal from aqueous solution,and achieved good treatment effects.They are composite materials with certain potential for treating thallium in water,and provide new materials and new methods for thallium pollution treatment.