The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolip...The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolipid and non-ionic biosurfactant saponin were used as washing solutions. Soil properties and the rare earth element fractions were analysed to define the effect of leaching on soil and elemental speciation. Column leaching results showed that saponin solution was more effective than rhamnolipid in the removal of the four rare earth elements tested, with the accumulative removal efficiency of La, Ce, Y and Eu following flushing with 400 mL of 25 g/L saponin, reaching 35.258%, 26.072%, 31.476% and 30.849%, respectively. The change in REE speciation showed that REE removed from soils were mainly derived from the acid-soluble and residual fractions released when rhamnolipid solution was used as a leaching agent. However, for saponin leaching, removed REE amounts were derived from acid-soluble and reducible fractions. Complexation interactions were identified between saponin and REEs, according to infrared spectroscopy and ion exchange data, with saponin complexing with La, Ce, Y, and Eu at a complex ratio of 1：1.展开更多
The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption...The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change（ΔG）values were –16.91 kJ/mol（La）,–16.05 kJ/mol（Nd）and –15.58 kJ/mol（Y）,respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.展开更多
The extraction kinetics of Gd（III） from the nitric acid medium using bis（2,4,4-trimethylpentyl） dithio- phosphinic acid （Cyanex301） and 2-ethylhexyl phosphoric acid （D2EHPA） in kerosene solution were measured ...The extraction kinetics of Gd（III） from the nitric acid medium using bis（2,4,4-trimethylpentyl） dithio- phosphinic acid （Cyanex301） and 2-ethylhexyl phosphoric acid （D2EHPA） in kerosene solution were measured by the single drop technique. The influences of hydrogen ion concentration, gadolinium ion concentration, extractant concentration, column height, and nozzle diameter on the extraction rate were investigated. The forward rate equations for the gadolinium extraction with D2EHPA and Cyanex301 were obtained. Based on the experimental results, the forward extraction rate constant was calculated. With the increase of D2EHPA or Cyanex301 concentration, the drop rising diameter and the value of interfacial tension decrease in the studied system, which shows that D2EHPA or Cyanex301 has interfacial activity as a kind of surfactant. Also, the droplet diameter and interfacial tension decrease with the increase of aqueous solution acidity. The experimental results show that the D2EHPA extractant provides faster extraction rate in comparison with Cyanex301 extractant, and it would be useful in industrial continuous extraction process.展开更多
基金supported by“Twelfth five-year”National Science and Technology Support Program(2012BAC11B07)National Natural Science Foundation of China(51664024)+1 种基金Outstanding Doctoral Dissertation Project Funding of Jiangxi University of Science and Technology(YB2016003)Talent Project of Jiangxi Province's Innovation-drive“5511”Program(20165BCB18013)
文摘The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolipid and non-ionic biosurfactant saponin were used as washing solutions. Soil properties and the rare earth element fractions were analysed to define the effect of leaching on soil and elemental speciation. Column leaching results showed that saponin solution was more effective than rhamnolipid in the removal of the four rare earth elements tested, with the accumulative removal efficiency of La, Ce, Y and Eu following flushing with 400 mL of 25 g/L saponin, reaching 35.258%, 26.072%, 31.476% and 30.849%, respectively. The change in REE speciation showed that REE removed from soils were mainly derived from the acid-soluble and residual fractions released when rhamnolipid solution was used as a leaching agent. However, for saponin leaching, removed REE amounts were derived from acid-soluble and reducible fractions. Complexation interactions were identified between saponin and REEs, according to infrared spectroscopy and ion exchange data, with saponin complexing with La, Ce, Y, and Eu at a complex ratio of 1：1.
基金Project supported by National Science and Technology Support Program of China(2015BAB16B01)Training Program of Major Academic and Technical Leaders in Jiangxi Province(20142BCB22005)Top Youth Talent Training Program of"Gan Po 555 Talents Project"of Jiangxi Province
文摘The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change（ΔG）values were –16.91 kJ/mol（La）,–16.05 kJ/mol（Nd）and –15.58 kJ/mol（Y）,respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.
基金financially supported by the Iran National Science Foundation(INSF)(No.90005452)
文摘The extraction kinetics of Gd（III） from the nitric acid medium using bis（2,4,4-trimethylpentyl） dithio- phosphinic acid （Cyanex301） and 2-ethylhexyl phosphoric acid （D2EHPA） in kerosene solution were measured by the single drop technique. The influences of hydrogen ion concentration, gadolinium ion concentration, extractant concentration, column height, and nozzle diameter on the extraction rate were investigated. The forward rate equations for the gadolinium extraction with D2EHPA and Cyanex301 were obtained. Based on the experimental results, the forward extraction rate constant was calculated. With the increase of D2EHPA or Cyanex301 concentration, the drop rising diameter and the value of interfacial tension decrease in the studied system, which shows that D2EHPA or Cyanex301 has interfacial activity as a kind of surfactant. Also, the droplet diameter and interfacial tension decrease with the increase of aqueous solution acidity. The experimental results show that the D2EHPA extractant provides faster extraction rate in comparison with Cyanex301 extractant, and it would be useful in industrial continuous extraction process.
