Optimization of amine-based hydrogel sorbents for CO2 capture: The role of crosslinkers

Amine-based hydrogel sorbents are gaining increasing attention for CO 2 capture application due to their long-term stability, simple fabrication, and compatibility with humid environments. These hydrogels are solidified with crosslinkers, which have a potentially large but unstudied influence on both the production process and the CO 2 uptake of the sorbent. Therefore, in this study, we systematically investigate how different crosslinkers influence the performance of polyethylenimine (PEI)-based hydrogel sorbents. Six crosslinkers representing acids, epoxides, and vinyl-based agents are initially screened based on crosslinking time, toxicity, and material cost. Subsequently, epichlorohydrin (ECH)-, trimethylolpropane triglycidyl ether (TTE)-, and 3-glycidyloxypropyltrimethoxysilane (GPTMS)-crosslinked particles are selected for detailed investigation on their CO 2 uptake and mechanical strength. Among the three, TTE-crosslinked particles show the highest CO 2 uptake, closely followed by GPTMS, with ECH significantly lower. All three crosslinkers result in sorbents with excellent cycling stability when using steam regeneration. GPTMS particles offer higher CO 2 uptake under low-humidity conditions and exhibit the best mechanical strength, which makes GPTMS as superior for the selected crosslinkers. Overall, the presented evaluation method provides practical guidelines for design and evaluation of durable, high-performance hydrogel sorbents for CO 2 capture. • Six crosslinkers were initially screened based on cost, toxicity, and processability. • ECH, TTE, and GPTMS were selected for fabricating PEI hydrogel sorbent particles. • CO 2 uptake was measured over time, water content, and under cyclic loading. • GPTMS-crosslinked particles show superior CO 2 uptake and mechanical strength.