One-pot synthesis of g-C3N4-doped amine-rich porous organic polymer for chlorophenol removal

A novel graphitic carbon nitride (g-C3N4)/amine-rich porous organic polymer (RAPOP) was synthesized via one-pot polymerization using various molar ratios of melamine (MA)/terephthalaldehyde (TA)/g-C3N4 of 4/4/1, 4/4/2 and 4/4/4. The g-C3N4 was used as a supporting scaffold, and its stratified structure provided a skeleton. Polymerization between MA and TA mostly occurred on the surface of g-C3N4, which formed porous spatial structures, in particular, that of MA/TA/g-C3N4 (4/4/2), of which the surface area and pore volume reached 540.36 m(2) g(-1) and 1.502 cm(3) g(-1), respectively. Their excellent adsorption performance towards 2,4-dichlorophenol was investigated under different conditions. A solution pH of 7 was favorable for adsorption. The presence of Na+ and Cl-ions had no adverse effects on the adsorption process, whereas humic acid (HA) led to a slight decrease in performance. Adsorption equilibrium was reached within 40 seconds, and the maximum adsorbed amounts were 188.70 mg g(-1), 217.39 mg g(-1), 238.10 mg g(-1) and 270.27 mg g(-1) for MA/TA (4/4), MA/TA/g-C3N4 (4/4/4), MA/TA/g-C3N4 (4/4/1) and MA/TA/g-C3N4 (4/4/2), respectively, at 298 K. Thermodynamic tests indicated that the adsorption proceeded spontaneously and endothermically. Moreover, the adsorbents maintained their high performance and stability after regeneration via treatment with alkali. This work demonstrates that g-C3N4/RAPOP can be practically employed to remove chlorophenols from aqueous solutions.