A Three-Dimensional Porous Organic Framework for Highly Selective Capture of Mercury and Copper Ions

In this study, a crystal porous organic framework (POF) belonging to ctn topology (POFct-1) is synthesized to selectively scavenge Hg(II) and Cu(II) ions. The maximum adsorption capacities of 167.19 mg g–1 and 135.60 mg g–1 are achieved toward Hg(II) and Cu(II) ions, respectively. In addition, the Langmuir isotherm model plus pseudo-second-order kinetic model for Hg(II) and Cu(II) ions can well describe the adsorption process of POFct-1. After five repeated uses, POFct-1 still exhibits high adsorption capacities. Conversely, a POF in amorphous form (POFct-2) is synthesized by changing the pressure and atmospheric conditions. The distribution coefficients of Cu (II) ions for the crystal (POFct-1) and amorphous (POFct-2) forms are 1.01 × 105 and 5.93 × 102 mL g–1 in a single ion solution, respectively. These results indicate that the POF in crystal form exhibits increased adsorption selectivity toward Cu(II) ions. The diverse structures and performances of POFs present them as promising candidates in selective adsorption of heavy metal ions.