Study On The Design And Construction Of Macroscopic Load Of Environmental Functional Nanomaterials And The Recovery Performance Of Low-concentration Rare Earth From Aqueous Solution

Rare earth elements?REEs?is called the"industrial monosodium glutamate".Rare earth materials show excellent physical properties such as catalytic,light,electricity,magnetism and superconductivity.So REEs are the important strategic resources.As a major producer and consumer of rare earth resources,China wastes a lot of rare earth resources in the process of production and development of rare earth resources and castoff containing large quantities of rare earth resources.The neglect of rare earth secondary resources is a waste of rare earth resources,and the rare earth elements as heavy metals can also even risk to ecosystems and human health.At present,due to the high specific surface area,high surface active sites,nano adsorbent could extracte heavy metals more efficiently.However,the small particle size also brings issues involving mass transport and excessive pressure drops when applied in fixed bed or any other flow-through systems,as well as certain difficulties in separation and reuse,and even possible risk to ecosystems and human health caused by the potential release of nanoparticles into the environment.An effective approach to overcoming the above technical bottlenecks is to fabricate hybrid nanocomposite by impregnating or coating the fine particles onto solid particles of larger size.Therefore,this paper has carried out a series of work on the macroscopic load of environmental functional nanomaterials and the recycling of low concentration of rare earth in water,and summarized as follows:?1?A carbon cloth?CC?supported nano-Mg?OH?₂?nano-Mg?OH?₂@CC?was synthesized by electrodeposition.The X-ray diffraction and scanning electron microscopy analysis demonstrated that the interlaced nano-sheet of Mg?OH?₂ grew firmly and uniformly on the surface of carbon cloth fibers.Batch adsorption experiments of Eu?III?indicated that the nano-Mg?OH?₂@CC composite maintained the excellent adsorption performance of nano-Mg?OH?₂toward Eu?III?.After adsorption,the composite containing Eu was calcined under nitrogen atmosphere.The content of Eu₂O₃ in the calcined material was as high as 99.66%.Fixed-bed column experiments indicated that no blockage for Mg?OH?₂@CC composite was observed during the treatment,while the complete blockage of occurred to nano-Mg?OH?₂ at an effluent volume of 240 m L.Moreover,the removal efficiency of Mg?OH?₂@CC was still higher than90%until 4200 mL of effluent volume.This work provides a promising method for feasible application of nanoadsorbents in fixed-bed process to recycle low-concentration REEs from wastewater.?2?In order to reduce the cost of composite materials,we choose green cheap nano-Mg?OH?₂as environmental functional nano materials and select sodium alginate?SA?as the carrier.In the process of sodium alginate cross-linking with calcium ion,a certain amount of nano-Mg?OH?₂ was mixed with sodium alginate,and SA@Mg?OH?₂ nanocomposites are successfully prepared.The optimum ratio of composite materials?SA:Mg?OH?₂:H₂O?was determined by the post-reaction turbidity?the leakage of the nanometer material?and the equilibrium adsorption capacity.XRD,SEM indicated that nano-Mg?OH?₂ was successfully loaded on the network of sodium alginate microspheres and maintain the flower-like structure.The adsorption capacity toward Eu of the composite material was enhanced,and the whole SA@Mg?OH?₂ microsphere could fully absorb the Eu?III?.Therefore,the excellent performance of SA@Mg?OH?₂ indicated that the loading nano-particle onto sodium alginate is a promising method to improve the application of nano-adsorption materials.?3?To make up for the deficiency of Mg?OH?₂ in the treatment of acidic wastewater,an available absorbent material GO@Tip-sponge was fabricated by coating reduced graphite oxide?GO?and Phosphoricacid titaniumsalt?TiP?on porous polyurethane?PU?sponges.The physicochemical properties of the GO@Tip-sponge indicated that it was recyclable and effective for Dy?III?.Results indicate that the GO@TiP-sponge shows a spongy porous structure and significantly enhances the Dy?III?removal compared with the single GO and GO@TiP.At the same time,it has a high adsorption capacity in a larger range pH condition,which could achieve extract REEs from the acid wastewater.According to the adsorption data,the adsorption mechanism of GO@TiP-sponge toward Dy?III?is the surface complexation and the coordinate covalent bond formation between Dy?III?and negatively charged functional groups.All the results suggested that GO@Tip-sponge has a widespread potential for applications in rare earth element adsorption as well as wastewater treatment.