Abstract: A method for extracting rare earth metals (e.g., lanthanides and/or actinides) from aqueous solution, the method comprising: (i) acidifying an aqueous solution containing said rare earth metals with sulfuric acid to result in an acidified aqueous solution containing 1-12 M concentration of sulfuric acid; and (ii) contacting the acidified aqueous solution with an aqueous-insoluble hydrophobic solution comprising a rare earth extractant molecule dissolved in an aqueous-insoluble hydrophobic solvent to result in extraction of one or more of the rare earth metals into the aqueous hydrophobic solution, wherein the rare earth extractant molecule has the following structure: wherein R1, R2, R3, and R4 are independently selected from hydrocarbon groups containing 1-20 carbon atoms, provided that the total carbon atoms in R1, R2, R3, and R4 is at least 12; and R5 and R6 are independently selected from hydrogen atom and hydrocarbon groups containing 1-3 carbon atoms.

Abstract: A method for extracting rare earth metals (e.g., lanthanides and/or actinides) from aqueous solution, the method comprising: (i) acidifying an aqueous solution containing said rare earth metals with sulfuric acid to result in an acidified aqueous solution containing 1-12 M concentration of sulfuric acid; and (ii) contacting the acidified aqueous solution with an aqueous-insoluble hydrophobic solution comprising a rare earth extractant molecule dissolved in an aqueous-insoluble hydrophobic solvent to result in extraction of one or more of the rare earth metals into the aqueous hydrophobic solution, wherein the rare earth extractant molecule has the following structure: wherein R1, R2, R3, and R4 are independently selected from hydrocarbon groups containing 1-20 carbon atoms, provided that the total carbon atoms in R1, R2, R3, and R4 is at least 12; and R5 and R6 are independently selected from hydrogen atom and hydrocarbon groups containing 1-3 carbon atoms.

Abstract: The invention relates to new calixarenes according to the formula: wherein R1 and R2, which may be identical or different, are alkyl, alkoxy or aryl groups, and n is an integer equal to 2, 3 or 4. Said calixarenes may be used to extract actinides and lanthanides from aqueous solutions.

Abstract: The invention involves a process for separating actinides and lanthanides by liquid-liquid extraction by means of calixarenes. These calixarenes have the formula: with R1 and R2 being alkyl groups or o-nitrophenoxy alkyl groups and R3 and R4 being aryl groups, and they are used in an organic liquid phase containing an organic diluent. The diluent and the calixarene concentration of the organic phase are chosen so as to ensure an enrichment of the organic phase with the actinide(s) and/or lanthanide(s) to be separated from an aqueous acid or saline solution.

Abstract: The invention involves the separation of actinides and lanthanides by membrane transport by means of a calixarene. To this end, a first aqueous solution containing at least one metal from the group of actinides and lanthanides to be separated is placed in the compartment 3 and a second aqueous re-extraction solution such as a 10−2 mol/L solution of HNO3 is placed in the compartment 5. The membrane 6 is a microporous membrane of which the pores are filled with a liquid organic phase (calixarene and diluent) chosen in order to favour membrane transport of the metal(s) to be separated from compartment 3 to compartment 5.