Perpustakaan Digital ITB

In order to meet the ever-increasing industrialdemand for rare-earth elements (REEs), it is desirable toseparate and recycle them at low concentrations from varioussources including industrial and urban wastes. Here, weintroduced phosphorus binding sites on the hydrophobicsurface of a robust and high-surface area porous polymerbackbone for environmentally benign and selective recovery ofREEs via adsorption. For this purpose, two porous covalentorganic polymer (COP) materials incorporated with in-builtphosphite functionality (P-COP-1 and P-COP-2) weresynthesized and applied for the adsorptive separation ofNd(III) ions from aqueous solution. A strategy to develop aseries of P-COPs via a simple Friedel?Crafts reaction wasintroduced, and their application to the selective adsorption of REEs was explored for thefirst time. The newly synthesized P-COPs were amorphous and/or weakly crystalline and showed excellent chemical stability and large specific surface area withsufficient mesoporosity for enhanced diffusion of REE ions. P-COP-1 exhibited an exceptionally high Nd(III) adsorptioncapacity of 321.0 mg/g, corresponding to the stoichiometric ratio of P/Nd(III) = 1:0.7 and high selectivity of >86% over othercompeting transition and alkaline earth metal ions, whereas P-COP-2 gave a Nd(III) adsorption capacity of 175.6 mg/g at 25°C and pH 5. Moreover, P-COP-1 showed a distribution coefficient value of 5.45×105mL/g, which is superior to otherbenchmark adsorbent materials reported so far. Finally, the P-COPs were reusable for a minimum of 10 cycles withoutdeterioration in adsorption capacities.