Chelation Properties of Some Phenolic‐Formaldehyde Polymers Toward Some Trivalent Lanthanide Ions

The chelation behavior of the phenolic‐formaldehyde polymers, poly(2,4‐dihydroxybenzoic acid‐3,5‐diylmethylene) polymer I, poly(2‐hydroxy‐benzoic acid‐3,5‐diylmethylene) polymer II, and poly(3‐hydroxybenzoic acid‐4,6‐diylmethylene) polymer III toward the trivalent lanthanide metal‐ions, La3+, Nd3+, Sm3+, Gd3+, and Tb3+ was studied by a static batch equilibration technique at 25°C as a function of contact time, pH, and counter ion. The highest metal‐ion uptake of these polymers was achieved at pH 7.0 and by using perchlorate as the counter ion. Results of the study revealed that polymer I has the highest metal‐ion uptake capacity, and that the metal‐ion uptake falls in the order: Tb3+ > Gd3+ > Sm3+ > Nd3+ > La3+.