Efficiencies And Mechanisms Of Antimony(?) Adsorption In Aqueous Solution By Nanosized Iron Oxides

This study designed batch experiments to explore the efficiencies and mechanisms of Sb(?)adsorption in aqueous solution by limonites from Xinqiao and Yeshan(Tongling,China)iron ore deposits,synthetic goethite,hematite,and maghemite.During experiments,the adsorption kinetics and thermodynamics were set as research emphases.Besides,effect factors such as p H,ion strength and anions were also studied.The main results are as follows:(1)Both Xinqiao and Yeshan limontes have high efficiencies on Sb(?)adsorption,Yeshan limonites have much higher Sb(?)adsorption ability than that of Xinqiao limonites.For all limonites,adsorption equilibrium can be achieved in 24 hours,and all adsorption processes can be described by pseudo-second-order model.As to adsorption thermodynamics,adsorption can be fitted well by Langmuir isothermal adsorption model for limonites without Mn,while Freundlich isothermal model is more suitable for Sb(?)adsorption by Mn-contained limonites.Adsorption is usually spontaneous endothermic reaction.The adsorption quantity of Sb(?)decrease with increasing p H,which is especially obvious for Mn-contained limonites.Anions such as phosphate can compete with Sb(?)and decrease its adsorption efficiency.(2)Mn oxides and Mn-contained goethite in limonites can enhance the detoxification and removal of Sb(?)through oxidizing Sb(?)to Sb(V).Thus,Mn-contained limonites are high performance Sb(?)removal materials.Furthermore,as limonites are often composed of nanosized minerals,Sb(?)removal efficiency is beyond doubt positive to the surface area of limonites.(3)Manually prepared goethite,and especially hematite and maghemite,also have good ability in Sb(?)removal.Kinetically,adsorption equilibrium can be achieved in 12 hours,and adsorption can be described by pseudo-second-order model.Thermodynamically,adsorption can be fitted well by Freundlich isothermal adsorption model for all three minerals,indicating heterogeneous adsorption.Thermodynamic parameters show that all adsorption is spontaneous endothermic reaction.For goethite,Sb(?)adsorption decreases with increasing p H.For hematite,Sb(?)adsorption is most favorable under neutral condition.Solution p H has little effect on Sb(?)adsorption by maghemite.Ion strength and anions have little effect on Sb(?)by all three minerals.(4)Calcination prepared hematite and maghemite are high performance materials in Sb(?)removal.In considering the recovery of adsorbent,maghemite is the Sb(?)removal material which deserves special concern.