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.