Calcium Oxide and Its Modified to Absorb Carbon Dioxide at Ambient Temperature and Pressure

• Main Authors: HSUEH-FEN HSU, 徐雪雰
• Other Authors: Yao-Hsuan Tseng
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/81876324969770455656

碩士 === 國立臺灣科技大學 === 化學工程系 === 104 === II ABSTRACT The rapid increase of carbon dioxide in the indoor space is resulted from the high population density, leading symptoms of dizziness and sleeping for human being. One of control target thus is carbon dioxide in indoor air quality management law. The concentration of carbon dioxide in indoor space can be controlled with ventilation, but the energy consumption for air conditioning will be increased obviously. In this study, calcium oxide was applied as an absorbent for carbon dioxide under the ambient condition. This system can be applied to control the concentration of carbon dioxide in indoor space. The absorption activity and reaction mechanism were investigated. The calcium oxide was modified via impregnation method with using alkaline metal salt solution. The result indicated the absorption rate for CO 2 is increased with the concentration of alkaline metal salt solution. Its crystal phase was converted to calcium hydroxide after modification as shown in X-ray diffraction pattern. The calcium oxide impregnated in the 8wt% of sodium salt can absorb 12 mmol of carbon dioxide within 5 h of peration. As shown in the absorption curve, the high absorption reaction rate was reached in the first 80 minutes, and the rate was reduced sharply after this period. This reason for this phenomenon is due to the formation of calcium carbonate on the surface of absorbent. It will retard the diffusion rate of CO 2 into the interior section. The effect of relative humidity on absorption rate was further investigated. The presence of high water vapor pressure enhanced the absorption rate and absorption amount for each absorbent. It is probably due to the calcium carbonate layer on the surface will be loose as it absorbs plenty water from air, resulting in the increase in the diffusion rate of carbon dioxide in this layer. CO 2 thus can react with the interior part of particles.