| Due to rare earth has borad application prospects and the excellent comprehensive properties,it is regarded as an indispensable strategic resource for the transformation of traditional industries in the world and the development of high-tech and defense advanced technologies.With the continuous improvement of the market demand and quality of rare earth and the new environmental requirements faced by enterprises,new challenges to the separation methods of rare earth are put forward.It is of great social and economic benefit to study the rare earth separation method of green and environmental protection for the preparation of high purity rare earth products and to improve the recovery and utilization of rare earth resources.At the same time,in the rare earth test,due to the high cost of inductively coupled plasma mass spectrometry(ICP-MS)and high testing cost,there is serious spectral interference in the common inductively coupled plasma emission spectroscopy(ICP-OES)and the atomic absorption spectrometry for the measurement of rare earth.Therefore,accurately testing the content of rare earth and impurities has become another urgent problem in the field of rare earth.In the common rare earth separation methods,the traditional methods such as solvent extraction,ion exchange,co-precipitation and electrolysis reduction have the problems of single separation,complex operation and pollution.It is the first task to study a kind of rare earth separation method with environmental protection,high efficiency,convenient operation and low energy consumption.This paper is based on the problems of the traditional separation method,taking into account that microbes are widely used in the environment and other fields because of their unique advantages,a microorganism,shewanella putrefaciens,that has a short growth cycle,easy cultivation and good tolerance to heavy metals is used as the research object,aiming at exploring a new method that microorganism is used for separate rare earth and impurities.In this paper,the method of biosorption is used to adsorb the elements by microorganism.The rare earth and impurity elements in the sample are adsorbed to the shewanella putrefaciens,and the adsorbed bacteria are eluted.The rare earth elements are separated from the impurity elements,and the rare earth elements La,Ce,Pr and Nd have a certain enrichment effect on the rare earth elements.The main contents and results are as follows:1.The best adsorption conditions were obtained by investigating the form,dosage,initial concentration and pH value,adsorption time and activity of the adsorbent.Under the optimal adsorption conditions,the 10 elements of Al,Fe,Ba,Mn,Pb,Zn,La,Ce,Pr and Nd were adsorbed at the same time.The adsorption rate of Al,Fe,Mn,Zn,Pb,La,Ce,Pr,and Nd reached 100%,and the adsorption rate of Ba was 75.15%.The saturated adsorption capacity of the other 8 elements is between 10~60mg/g.The adsorption effect of La and Ce by Ba is better than that of Fe,and the sorption of Fe is preferentially adsorbed.2.Through the single element adsorption experiment,the saturated adsorption capacity of the 10 elements was obtained accurately: La,Ce,Pr and Nd were 234.83,311.49,49.58 and 59.93mg/g respectively;the saturated adsorption capacity of Fe,Ba and Pb was between 30~50mg/g;the adsorption of Al,Mn and Zn was poor,17.95,11.12,and 10.57mg/g respectively.3.Cation exchange resin 732-1 is adsorbed to 10 elements such as Al,Fe,Ba and so on.The adsorption capacity of each element in 72 h is below 30mg/g;active carbon has a certain adsorption to 7 elements,such as Fe and Ba,and almost no adsorption on Mn and Zn;because the two materials will introduce more impurities during the adsorption process,so it is not applicable in separation of elements.4.The four step elution methods can separate rare earth from impurity elements.The removal rate of Al,Fe,Mn,Zn and Pb is 100%,and the removal rate of Ba is 64.06%.At the same time,more than 98% of La,Ce,Pr and Nd were enriched in the liquid phase.Because dead bacteria do not have biological activity,Ba,La,Ce,Pr and Nd cannot be eluted from dead bacteria.5.The thermodynamic and kinetic behavior of the 10 elements adsorbed by shewanella putrefaciens was discussed.It was found that the molar reaction enthalpy of the 10 elements was positive,indicating that the adsorption reaction of the 10 elements was the endothermic reaction;the adsorption of Ba,La,Ce,Pr and Nd was better compound quasi-second rate equation.This method can separate the rare earth and impurity elements effectively.It has the advantages of simple operation,environmental protection and high efficiency.It provides a new method for the preparation of high purity rare earth and the recovery and utilization of La,Ce,Pr and Nd.Thermodynamic and kinetic data have certain practical significance for guiding industrial production.At the same time,by separating the impurity elements Al,Fe,Mn,Zn and Pb with the rare earth elements La,Ce,Pr and Nd,the spectral interference caused by ICP-OES in the rare earth element is eliminated,which has certain practical value. |
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