Catalyst-free synthesis of triazine-based porous organic polymers for Hg2+ adsorptive removal from aqueous solution

The triazine-based porous organic polymers were synthesized by a one-pot amidation polycondensation reaction and they were applied for Hg2+ removal from aqueous solution. The results showed that these polymers had high Brunauer-Emmett-Teller (BET) surface area (404-521 m(2)/g) and hierarchical porosity with dominated micropores and mesopores. The equilibrium data for Hg2+ adsorption followed the Langmuir model with the maximum capacity of 229.9 mg/g. The Hg2+ concentration at the initial concentration of 6.0 ppm reduced to 6 ppb after 20 min, verifying its fast and deep treatment of Hg2+ wastewater. The adsorption was rapid and the pseudo-second-order rate model characterized the kinetic data perfectly. Moreover, the polymers exhibited excellent selectivity, easy regeneration, and superior reusability, indicative of their outstanding performance for Hg2+ removal. Analysis of the adsorption mechanism revealed that the embedded carboxyl, triazine ring, and amino groups played significant role due to the strong chelating coordination of the oxygen and nitrogen with Hg2+.