Novel porous hydrogel beads based on amidoxime modified polymer of intrinsic microporosity for efficient cationic dye removal

Due to the high surface area and facile functionalized or modified groups of polymers of intrinsic microporosity, and the hydrophilicity of sodium alginate (SA), a simple strategy was proposed for preparing porous composite hydrogel beads with excellent cationic dye adsorption capacity and selectivity. The porous composite hydrogel beads were prepared by introducing the amidoxime modified polymers of intrinsic microporosity (AOPIM-1) into SA polymer solution and then dropping the mixture into CaCl2 aqueous solution at low temperature for crosslinking. The prepared porous SA/AOPIM-1 hydrogel beads performed excellent adsorption capacity on Rhodamine B (RhB) from aqueous solution and the Langmuir model was suitable for describing the adsorption behavior of RhB on porous SA/AOPIM-1 hydrogel beads. It is surprising that the maximum theoretical adsorption capacity obtained by fitting the Langmuir model was up to 1648.3 mg·g−1. More importantly, porous SA/AOPIM-1 hydrogel beads showed outstanding selective adsorption capacity for cationic dyes in the mixed anionic and cationic dyes solution. Besides, the adsorption capacity of porous SA/AOPIM-1 hydrogel beads could maintain above 80 % of the initial adsorption capacity after 10 adsorption/desorption cycles. The above results indicate that porous SA/AOPIM-1 hydrogel beads can be used as a promising adsorbent with for effective removal of dyes from wastewater treatment.