Salt-polymer templates-directed-syntheses of porous polyether frameworks for efficiently chelating heavy metal ions

Preparation of porous organic frameworks (POFs) with large specific surface area is still an important research issue due to application of POFs in adsorption of heavy metal ions. In this paper, a new method was development for preparing nitrogen- and oxygen-containing POFs with large specific surface area values. salt-polymer (K2CO3, Na2SO4 and polystyrene) were employed as templates for formation of pore canals with designed pore diameter values. Experimental results showed that the specific surface area values (3780.80–––5115.70 m2 g−1) of three POFs synthesized by the new salt-polymer template (SPT) methods were 8.04–––13.45 times as much as those (380.35–––530.50 m2 g−1) of corresponding three POFs synthesized by the salt template (ST) methods and 4.98–––6.73 times as much as commercial activated carbon (759.8 m2 g−1). The maximal adsorption capacities (qmax) values of POFs synthesized by the SPT methods for heavy metal ions were much larger than those of commercial activated carbon. Especially, the qmax value of poly(1,5-dihydroxynaphthalene-alt-1,3,5-triazine) for Cd2+ ions was 230 mg g−1. The time values (20 min) of equilibrium adsorption of those POFs for heavy metal ions were short. Therefore, the salt-polymer template-directed synthesis would be a convenient and effective method of preparation of excellent POFs with large specific surface area values and good adsorption properties.