氢氧化钙的固碳功能性研究-CO2浓度与碳化时间的影响

Carbon sequestration functionality of calcium hydroxide - Effect of CO2 concentration and carbonation time

矿物固碳是降低大气中CO2浓度的有效方法之一,但是目前大量的研究集中于提高矿物固碳效率,而忽略了碳化产物的二次利用问题。本文采用氢氧化钙固碳,研究了CO2浓度和碳化时间对碳化速率以及碳化产物强度的影响。研究发现,在相同CO2浓度下,氢氧化钙碳化速率随碳化时间的延长而逐渐提高;随着CO2浓度的增加,氢氧化钙的碳化速度不断增大;随碳化时间的延长,碳化产物的强度不断提高,但是当碳化时间超过24 h后,碳化产物的强度明显下降。高浓度CO2环境对氢氧化钙碳化产物的强度发展不利,随CO2浓度的增加碳化产物的强度逐渐降低。通过SEM、EDS和XRD分析发现,随着碳化时间的延长,氢氧化钙表面形成方解石型碳酸钙层,阻碍了碳化进程;当碳化时间达到28 d时,由于碳酸钙层的胀裂,碳化产物的强度出现明显下降。

Mineral carbon sequestration is one of the effective methods to reduce CO2 concentration in the atmosphere.However,a large number of researches focus on improving the efficiency of mineral carbon sequestration,and ignore the secondary utilization of carbonized products.In this paper,the effects of CO2 concentration and carbonization time on carbonization rate and compressive strength of carbonization product were studied.It was found that the carbonization rate of calcium hydroxide increased gradually with the extension of carbonization time under the same CO2 concentration.With the increase of CO2 concentration,the carbonization rate of calcium hydroxide increased continuously.With the extension of carbonization time,the strength of carbonized products increased continuously,but when the carbonization time exceeded 24 h,the strength of carbonized products significantly decreased.High concentration CO2 environment was unfavorable to the development of strength of calcium hydroxide carbonization products,and the strength of carbonization products gradually decreased with the increase of CO2 concentration.Through SEM,EDS and XRD analysis,it was found that with the extension of carbonization time,calcite type calcium carbonate layer formed on the surface of calcium hydroxide,which hindered the carbonization process.When the carbonization time reached 28 d,the strength of carbonized products decreased significantly due to the expansion and cracking of calcium carbonate layer.