Adsorption Of Rare Earth Elements La、Nd By Clay Minerals And Inorganic Elements Of Soils

This paper adopted Oscillation-Balance method to research the feature of absorbability of the six kinds of clay minerals (Kaoline, Bentonite, Attapulgite, Semectite, Illite and Chlorite) and the inorganic elements of three different soils (red soil, yellow cinnamon soil, shajiang black soil) on low concentration in two light rare earth elements La、Nd solution, and compare the differences in La、Nd single system and mixed system,then judged whether there are cooperation、competition、antagonism and inhibition between the absorbability of La and Nd.Utilized ICP to determine equilibrium concentration and adsorption, and drew adsorption isotherm curves and fitting thermodynamic equations of adsorption.The results indicated that:1. In the single system of low concentration Ree (La,Nd):①The six kinds of clay minerals have good adsorption performance on REE (La, Nd). Among them, Langmuir equation can describe better the isothermal adsorption process of attapulgite, chlorite and bentonite to the rare earth elements (La、Nd) on the low density occasion. While the adsorption process of Semectite can be better described by Frendlich equation.②he order of six kinds of clay minerals’ adsorption to REE (La, Nd) is:Semectite> bentonite> illite> chlorite> attapulgite> kaoline. The difference of adsorption performance mainly decided by the structure of minerals.Generally speaking, that is type of2:1>type of2:1:1>type of double-chain> type of1:1.③he unit of the adsorption quantity of clay mineral to the rare earth element is less than humic acid. But for the content of clay minerals is outweigh humic acid in the natural soil. As for the residue of exogenous rare earth in the soil, the clay mineral is the main part in the gross of adsoption.④he unit adsorption of inorganic elements of soil is less than the pure clay minerals.On the consideration of the relevant ratio, Langmuir equation can described better the three kinds of soil inorganic element’s process of adsorption performance under the condition of low concentration.⑤he order of adsorption performance of three soil inorganic element on La is:yellow cinnamon soil>shajiang black soil> red soil; while the adsorption performance on Nd has displayed two stages,that is,on low concentration:yellow cinnamon soil>shajiang black soil> red soil; and on high concentration area, red soil>yellow cinnamon soil>shajiang black soil.2.1n the mixed system of low concentration La and Nd:①angmuir equation can describe better the isothermal adsorption process of kaolinite、attapulgite、chlorite to the rare earth elements(La、Nd) on the low density occasion in the mixed system. The isothermal adsorption process of Semectite and bentonite to the rare earth elements of low concentration can be better descripde by Frendlich equation.②he order of six kinds of clay minerals’adsorption to the gross of REE La and Nd is Semectite> bentonite> illite>attapulgite>kaoline>chlorite.Generally speaking, that is type of2:1>type of double-chain>type of1:1>type of2:1:1.③enerally, the adsorption effect of clay minerals except the kaolinon to La and Nd in low concentration mixed system were independent function. The adsorption on the La and Nd agree with3:2proportion, which is accordance with the training environment. The total adsorption to the two rare earth elements can be calculated by the adsorption in a single system according to the proportion of3:2(La:Nd).④he adsorption effect of the La consist with the Nd by Kaolin in the mixed system of the rare earth elements. There were cooperate and antagonism on different concentration section in Attapulgite’s adsorption process;Chlorite’s adsorption process have antagonistion between the two elements.⑤he adsorption process of the three kinds of soil inorganic element to the rare earth elements (La, Nd) can be better described by the Langmuir equation. The order of total adsorption capability of three soil inorganic element on REE is:yellow cinnamon soil>shajiang black soil>red soil.⑥he adsorption effect of the La Antagonistic with the Nd by red soil inorganic element in the mixed system of the rare earth elements.While there were competition between La and Nd in the adsorption process of the inorganic element of yellow cinnamon soil and shajiang black soi.The amount of the adsorption to La and Nd on the high concentration can not be simple calculated by the two adsorption in single system accorded the proportion of3:2(La:Nd).