Abstract: This paper describes the preparation of macroreticular polymethylmethacrylate beads by means of suspension polymerization, which is then loaded with mono-2-ethylhexyl 2-ethylhexylphosphonic acid(designated as P 507).The effects of degree of cross-linking, composition and amount of pore-produring agent added upon the pore structure of the resin beads are discussed. It is found that, good and poor solvents in various "proportions may produce resins with different pore structures.By increasing the amount of pore-producing agent, the apparent specific gravity, ρ₂, decreases, while specific surface area, S, pore volume, PV, and average pore diameter,D, increase. Both ρ₂ and S increase, and PV and D decrease, when the degree of cross-linking increases from 10 to 35%.Increasing the proportion of good solvent in pore-producing agent, increase ρ₂ and S, decrease PV and D. A series of macroreticular resin beads with different pore structure has been prepared, and compared for their effectiveness in the separation of lanthanum, cerium, praseodymium and neodymium mixture under identical conditions.Experimental results show that pore structure of the P 507 loaded polymethylmethacrylate beads plays an important role in the separation of rare earths. With polymethylmethacrylate beads of appropriate pore structure, the separation of rare earths by means of extractive chromatograchy can be achieved satisfactorily.

Key words: Extraction chromatography, Separation of rare earth, elements, Extractant loaded resin, Pore structure of resin beads