Effects of CO₂ capture on waste concrete/sodium nitrate form-stable phase change composites for energy storage

A large quantity of building waste concrete is produced annually in China, which pollutes our ecological environment with its strong alkalinity. To recycle the building waste concrete, capture carbon dioxide at a low price, produce low-carbon, low-cost energy storage materials to provide clean energy for buildings. This work showcases a clever and forward-thinking approach by harnessing the carbon sequestration potential of building waste concrete. In a groundbreaking move, the researchers ingeniously exploited concrete from building waste to not only capture carbon dioxide, but also convert it into form-stable phase change composites, which were later carried out in detailed comparative analysis. Results show that the carbon capture efficiency of the building waste concrete reaches 24.7 % under the specific experimental conditions. The latent heat of the form-stable phase change composite prepared by carbon capture is higher (C-SS3, 50.31 J/g) than that without carbon capture (SS3, 39.84 J/g) by adding the same mass fraction of phase change material. In the range of 100-400 degrees C, the highest TES densities of sample SS4 and sample C-SS3 reached 339.78 J/g and 303.30 J/g, respectively. The compressive strength of SS2 is the highest, which is 121.54 MPa, and the compressive strength of both the building waste concrete and the form-stable phase change composite increased after carbon capture process. The thermal conductivity of the samples after carbonization (0.648 W/(m center dot K)) was lower than that of before carbonization (0.884 W/(m center dot K)). The form-stable phase change composites before and after carbon capture have good chemical compatibility among the components, and the form-stable phase change materials are densely bonded with the skeleton materials. Experimental verified the feasibility of preparing form-stable phase change composites using building waste concrete before and after carbon capture as a skeleton material.