Lipophilic guanidinium compounds for removal of oxyanions from aqueous solutions

A method for removing an oxyanion from an aqueous source containing said oxyanion, the method comprising contacting said aqueous source with an aqueous-insoluble hydrophobic solution containing an oxyanion extractant compound dissolved in an aqueous-insoluble hydrophobic solvent to result in formation of an oxyanion salt of said oxyanion extractant compound and extraction of said oxyanion salt of said oxyanion extractant compound into said aqueous-insoluble hydrophobic solution, wherein said extraction results in an extraction affinity (D) of said oxyanion of at least 1, wherein D is the concentration ratio of said oxyanion in the organic phase divided by the concentration of said oxyanion in the aqueous phase;

• wherein said oxyanion extractant compound has the following structure:
• wherein:
• R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are independently selected from (i) hydrogen atom, (ii) hydrocarbon groups (R) containing 1-30 carbon atoms and optionally substituted with one or more fluorine atoms, (iii) —OR′ groups, and (iv) —NR′2 groups, wherein R′ groups are independently selected from R groups and hydrogen atoms, provided that at least one of R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 is selected from:
• R groups containing 4-30 carbon atoms, or —OR groups with R containing 4-30 carbon atoms, or —NR′2 groups with at least one R′ group being R containing 4-30 carbon atoms;
• R11 and R12 are independently selected from hydrogen atom and methyl group;
• Xm− is an anionic species with a magnitude of charge m, where m is an integer of at least 1, provided that Xm− is an anionic species exchangeable with the oxyanion in said aqueous source before said oxyanion extractant compound contacts said aqueous source, and Xm− is said oxyanion in the oxyanion salt of said oxyanion extractant compound;
• and
• n is a number, provided that n×m=1.