Synergistic Mechanism of Particulate Matter (PM) from Coal Combustion and Saponin from Camellia Seed Pomace in Stabilizing CO_2 Foam

摘要

Particulate matter (PM), generated during coal combustion for energy production, is a serious pollution risk to atmospheric environment. Its utilization as an industrial byproduct is an attractive endeavor all over the world. In this work, novel aqueous CO2 foam stabilized by PM from coal combustion in combination with saponin (COSA(1)) from camellia seed pomace was explored. Addition of COSA(1) effectively promoted the dispersion of PM into the aqueous solution through adsorbing onto particle surface and increasing their zeta (zeta) potential. Hence, PM-stabilized foam could be generated much more effectively. In the presence of COSA(1), PM migrated to the CO2/liquid interface and formed an "armor" surrounding the bubbles. The surface of the bubbles became solidlike and in the presence of PM, for bubble with 3.2 mM COSA(1), the interfacial dilatational viscoelastic modulus dramatically increased from 23 to 65 mN/m. In addition, PM at the interface shielded CO2 gas from the surrounding liquid leading to much slower diffusion of CO2 between the bubbles, despite the small bubble size, leading to more stable foam with an average bubble diameter of similar to 110 mu m similar to 5000 s after generation. Moreover, particle adsorption increased the interfacial viscoelasticity of COSA(1)/PM foam film leading to higher apparent viscosity, relative to bare COSA(1) foam. Nevertheless, high viscosity increases energy dissipation during foam generation and, hence, decreases foaming ability. The mechanical intensity of the adsorbed particle layer overweighed the interfacial tension (IFT) action and resulted in extremely rough bubbles. The high-performance PM-stabilized CO2 foam could potentially be used in enhancing oil recovery, hydraulic fracturing, fire-fighting, mineral flotation, etc.