Carbon dioxide capturing evaluation of polyacryloyl hydrazide solutions via rheological analysis for carbon utilization applications

Abstract

PAHz is a relatively inexpensive material which has several industrial applications but its interaction and utilization in conjunction with CO2 has not been explored. In this study, carbon dioxide (CO2) capturing potential of a polymeric material viz., polyacryloyl hydrazide (PAHz) with specific hydrazide functional group is reported. Characterization tools i.e., microscopic, absorption rate kinetics and rheological analysis were used to determine optimum composition ensuing CO2 uptake via interaction between functional group and CO2 molecules. A varying concentration i.e., 5–30 wt% of PAHz was used. PAHz solution with ≤10 wt% was entirely saturated by small size CO2 bubbles and absorption increases with increasing equilibrium pressure as shown by molality results. With high PAHz concentration >10 wt%, capturing of CO2 markedly decreased and globules of moderately entrapped gas caused reduction in aqueous phase participating in CO2 absorption. CO2 responsiveness with a functional group to develop gelling in solution depended on PAHz concentration. At low concentration, PAHz chains were lesser in population which developed preliminary gelling in solution while high concentration produced sufficient PAHz chains for CO2 interaction. This resulted in the solution to display premature gelling that restricted further entry of CO2, and several CO2 bubbles aggregated near top of solution. In presence of CO2, a sol-gel transition in PAHz solution was anticipated when concentration ∼15 wt%. Finally, rheological investigations were performed to find out the effect of CO2 capturing on the rheological behaviour of solutions. The rheological properties (viscosity and moduli) for 5 and 10 wt% PAHz solutions did not change much after CO2 capturing and stable Newtonian behaviour was observed. The observations presented in the study present a strong case for application of liquid PAHz sample for use as mobility control agent during CO2 injection for EOR and carbon geo-sequestration.