Study on the feasibility of improving the indoor air quality from the perspective of circular economy by activation of biological calcium

In order to cope with excessive use of energy since the industrial revolution, environment has been seriously polluted and the large amount of waste has been produced. The circular economy has become the driving force for sustainable development of the earth, with the aim of maximizing resource efficiency and minimizing environmental impacts with the hope of achieving a vision of zero waste and friendly environment. As consumption of eggs increases, most of the discarded shells produced each year are treated as waste, which pollute environment. Researches on the environmental restoration of eggshells as an absorbent have brought a lot of results, but it is only used for absorbing industrial heavy metals, dye and for energy catalysis. The edible biological calcium of eggshell and its multi-layer microporous structure provide a good absorbing property. Therefore, based on literature, this study will observe the microporous structure through electron microscopy (SEM), and by (XRD) to analyze the crystal structure, pH value and redox potential (ORP), for finding the most economical and absorption-efficient calcination time and temperature. After eggshells are calcined for two hours at 900 degree Celsius, its detection value has become constant (or nearly), and its structure has also changed from the original shale-flake to a multi-layer microporous structure showing physical absorption capacity for indoor air pollutants, and its chemical absorption conditions are also effective. Preliminary experiments also show degradation results for indoor air pollution. This research can be further used for a study of absorption performance to improve indoor air quality, and as a reference for application and development as a green building material.