Fabrication of a family of porous azo polymers with multifunctional adsorption and separation performances

Abstract

In this paper, a class of porous organic polymers (POPs) of p-hydroxy azobenzene with a mesoporous structure was designed and synthesized by a –NN– coupling reaction of tetraamino-metal phthalocyanine (MTAPc, where M = Co, Ni or Cu) with hydroquinone (namely Azo-MHQ, where M = Co, Ni or Cu). The Azo-MHQ materials possessed good thermal stabilities, excellent dispersibilities in water, polar and non-polar organic solvents, as well as excellent chemical stabilities. Among them, Azo-CuHQ showed an outstanding iodine trapping ability in an iodine solution and vapor with saturated adsorption capacities of 1347.47 mg g−1 and 118 wt%. In addition, Azo-CuHQ also showed a high adsorption capacity for methylene blue (MB) with the adsorption amount of 191.21 mg g−1. Furthermore, by loading Azo-CuHQ onto polyethersulfone (PES) membrane, the water permeability of the obtained membranes reached 147.03 L m−2 h−1 bar−1, and the retention rate of Ag in a very low concentration solution of 20 ppm was 56.8 %. Additionally, a thorough analysis of the Azo-CuHQ adsorption and separation mechanism was conducted. A novel approach to the design and synthesis of a class of materials with multifunctional adsorption and separation capabilities is presented in this research.