Synthesis, characterization and adsorption properties of an amide-modified hyper-cross-linked resin†
Friedel–Crafts reaction, amination reaction and acetylation reaction were performed with chloromethylated polystyrene (CMPS), and amide-modified hyper-cross-linked resin, HCP-EDA-AA, was prepared. The prepared HCP-EDA-AA owned predominant nanopores and medium polarity, making it possess superior adsorption performance to salicylic acid as compared with the raw material CMPS and the intermediate products, hyper-cross-linked polymer (HCP) and the ethylenediamine-modified hyper-cross-linked resin (HCP-EDA). The Langmuir model characterized the equilibrium data better than the Freundlich model. At a feed concentration of 800.5 mg L−1 and a flow rate of 67 mL h−1, the dynamic capacity of salicylic acid on HCP-EDA-AA was 267.8 mg g−1, very close to the extrapolated value by the Langmuir model (273.9 mg g−1). The salicylic acid adsorbed HCP-EDA-AA resin column was almost regenerated by a mixed desorption solvent including 0.01 mol L−1 of sodium hydroxide (w/v) and 20% of ethanol (v/v). HCP-EDA-AA was repeatedly used nine times and the equilibrium capacity for the ninth time reached 95.5% of the equilibrium capacity for the first time.