Construction Of 3D Porous Metal Oxide Microspheres For The Study In Separation And Recovery Of Rare Metals

In recent years,with the continuous development of advanced technology,rare metals have been widely developed and utilized in various fields,and the demand for rare metals in industrial production is also growing.The storage of rare metals in the earth's crust is limited,and the resources of rare metals are precious.In order to fully exploit the resources of rare metals,it is essential to effectively separate and recover rare metals from waste water containing rare metals.3D porous transition metal oxides are widely used in adsorption technology due to their special structure and stable chemical properties.The 3D porous structure can provide more adsorption sites,which facilitate the transport of the adsorbates to the adsorption sites,increases the adsorption capacity and the adsorption rate.Two kinds of 3D porous transition metal oxide microspheres?ZrO₂ and?-FeOOH?were prepared as high affinity adsorbents for simultaneous recovery of selenium and tellurium,gallium and germanium in aqueous solution.And by controlling adsorption conditions,they can be selectively separated.It provides a new strategy for the separation and recovery of chemically similar rare metals,which can be applied to the separation and recovery of rare metals in actual industrial and environmental waters.The work of this thesis is as follows:The 3D porous ZrO₂ microspheres with high chemical affinity for Se?IV?and Te?IV?were designed and synthesized.The surface is rough and rich in mesopores,which can provide more active sites for adsorption.Experiments show that 3D ZrO₂has good adsorption capacity for Se?IV?and Te?IV?,and reaches adsorption equilibrium at short notice.The saturated adsorption capacities of 3D ZrO₂ to Se?IV?and Te?IV?are 9.47 and 18.92 mg g^-1,respectively.Simultaneous recovery of Se?IV?and Te?IV?is achieved in the range of pH 2-10,and the recovery efficiency of Se?IV?and Te?IV?can reach more than 90%.It was found that the introduction of PO₄^3-can effectively separate the co-adsorbed Se?IV?and Te?IV?by ion exchange in the co-adsorption system.In addition,the 3D ZrO₂ microspheres have excellent acid and alkali resistance and structural stability.The adsorption efficiencies of Se?IV?and Te?IV?are maintained above 85%after repeated use for more than 5 times.3D ZrO₂ microspheres also exhibit excellent interference capability,and Se?IV?and Te?IV?adsorption efficiencies are hardly affected in a variety of heavy metal ions coexisting systems.The kinetics,thermodynamic behaviors of the adsorption processes and the changes in the structure of the adsorbent during the adsorption process were explored to reveal the adsorption mechanisms.A recovery method for the efficient separation and enrichment of Se?IV?and Te?IV?in industrial wastewater was established.The constructed 3D ZrO₂microspheres can effectively recover and selectively separate Se?IV?and Te?IV?,which provides a theoretical basis for the recovery and reuse of selenium and tellurium in practical industrial wastewater.The effects of FeOOHs with polycrystal and different morphologies on the effective adsorption of Ga?III?and Ge?IV?were investigated.The experimental results show that the maximum saturated adsorption capacity of 3D porous flower-like?-FeOOH is 52.36 and 55.77 mg g^-1 for Ga?III?and Ge?IV?,respectively,mainly because?-crystal form has stronger chemical affinity for the targets.And the 3D porous flower structure can effectively increase the specific surface area and provide more adsorption sites for adsorption.A recovery method for the efficient separation and enrichment of Ga?III?and Ge?IV?in wastewater was established.In the range of pH 7-8,the simultaneous recovery of Ga?III?and Ge?IV?can be achieved,and the recovery efficiencies of Ga?III?and Ge?IV?can reach 98.5%or more.And at pH 12,Ga?III?and Ge?IV?can be selectively separated.In addition,the 3D flower-like?-FeOOH structure is stable,and the adsorption efficiencies of Ga?III?and Ge?IV?are maintained above 78%after repeated use for 4 times.After interference experiments,the adsorption efficiencies of Ga?III?and Ge?IV?were almost unaffected in a variety of anions and cations coexisting systems.In addition,the kinetics,thermodynamic behaviors of the adsorption process and changes in the structure of the adsorbent during the adsorption process were explored to reveal the adsorption mechanism.This paper provides a new strategy for simultaneous recovery and selective separation of Ga?III?and Ge?IV?in industrial waste.