Preparation and Properties of A Hyperbranch-Structured Polyamine adsorbent for Carbon Dioxide Capture.

A fibrous adsorbent with amino-terminated hyperbranch structure (PP-AM-HBP-NH2) was prepared by grafting hyperbranched polyamine (HBP-NH2) onto the acrylamide-modified polypropylene (PP) fibers. The grafting of AM on PP fibers provided the active sites for introducing HBP-NH2 onto the PP fibers. This kind of "grafting to" procedure to synthesize hyperbranch-structured fiber could overcome the disadvantages of stepwise growth procedure, avoiding the complicated synthesis process and the requirement of strict experimental conditions. The grafted HBP-NH2 was three-dimensional dentritic architecture and had a large number of pores existing within the grafted polymers, which is favorable for CO2 molecules to diffuse into the HBP-NH2. Therefore, the as-prepared PP-AM-HBP-NH2 fibers showed a high adsorption capacity (5.64 mmol/g) for CO2 in the presence of water at 25 °C, and the utilization efficiency of alkyl amino groups could reach 88.2%, demonstrating that the hyperbranched structure of adsorbents can greatly promote adsorption capacity and efficiency. This could be attributed to better swelling properties and lower mass transfer resistance to CO2 of the hyperbranched adsorbent. PP-AM-HBP-NH2 also showed excellent regeneration performance, and it could maintain the same adsorption capacity for CO2 after 15 recycle numbers as the fresh adsorbent.