Preparation Of Magnetic Adsorbents And Their Adsorption Behavior For Low Concentration Rare Earth

Rare earth is a strategic resource that has attracted worldwide attention.As a non renewable resource,the reserves of rare earth resources are decreasing day by day due to long-term exploitation.How to improve the utilization efficiency of resources has always been the focus of researchers.The existing rare earth mining process produces a large number of low concentration rare earth wastewater,from which the enrichment and separation of rare earth elements can greatly improve the utilization efficiency of rare earth resources.Aiming at the problems of emulsification and three-phase in traditional liquid-liquid extraction,the synergy between reagents was introduced into the preparation of adsorption materials,and the preparation,physicochemical properties and adsorption behavior of magnetic adsorption materials and their effects on the adsorption and separation of rare earth elements were studied,The main results of this paper are as follows:1.Magnetic adsorption material MPCA was prepared.In this paper,the synergism between the agents and the introduction of Fe₃O₄ nanoparticles to the preparation of adsorbent materials were carried out,and the preparation of adsorbent was studied.P507 and Cyanex272were embedded by silica sol gel method.Fe₃O₄@Si O₂ Separately embedded adsorbents MPA,MCA and mixed embedded adsorbent MPCA are respectively prepared and used to adsorb rare earth ions.Compared with the conventional grafting of official energy groups on the surface of silica,it has simple operation and does not need complex chemical reaction,which can effectively reduce the difficulty and cost of solid-liquid separation,greatly reduce the use of organic phase,and is more eco-friendly,At the same time,there will be no emulsification,three-phase and other phenomena in traditional liquid-liquid extraction.2.The performance characterization experiment of magnetic adsorbent was carried out.The results show that P507 and Cyanex272 have been successfully embedded in the adsorbent,with stable properties and strong magnetic response,and the specific surface area is 257.04m²/g.The average pore diameter is 10.18 nm,and the pore structure is mainly mesoporous;Before and after adsorption,the infrared characteristic peak of PO（OH）functional group shifted,indicating that lutetium ion coordinated with PO（OH）functional group during adsorption.3.The results show that under the condition of external magnetic field,MPCA adsorbent can be quickly adsorbed by magnet to complete solid-liquid separation;When p H=2,the maximum synergistic effect can be obtained,the synergistic coefficient is 22,and the adsorption capacity is about 0.07 mmol/g.increasing the temperature can improve the adsorption effect to a certain extent.With the increase of ionic strength,competitive adsorption occurs,which weakens the adsorption effect;The desorption and circulation experiments showed that 2 mol/L hydrochloric acid solution had better desorption effect.After three cycles,the adsorption capacity of MPCA adsorbent was 99.5%of the initial adsorption capacity.;In the total rare earth adsorption experiment,compared with liquid-liquid extraction,the synergistic extraction system constructed by P507 and C272 has better enrichment effect on rare earth elements in solid-liquid adsorption.MPCA adsorbent has strong adsorption capacity for medium and heavy rare earth and the strongest adsorption capacity for lutetium.4.The thermodynamics and kinetics of Rare Earth Adsorption by magnetic materials were studied.The results show that the adsorption of lutetium ion by MPCA adsorbent is a spontaneous endothermic reaction,and increasing the temperature is conducive to the adsorption;The adsorption of lutetium ion by MPCA adsorbent has the highest fit with the second-order kinetic model.