论文部分内容阅读
废弃混凝土间接碳酸化封存CO2的重要一步是将Ca2+从混凝土中提取出来。论文对废弃混凝土中Ca2+的提取进行了研究,主要考察了提取溶剂、混凝土粒径、温度和固液比等对Ca2+提取过程的影响。对不同的提取溶剂进行了比较,发现HNO3作为溶剂时Ca2+提取率最高,其次为CH3COOH、HCOOH和H2SO4。减小混凝土粒径可有效提高Ca2+提取率。对粒径小于0.15 mm的混凝土,Ca2+提取率随温度升高而增大,其最佳固液比为40 g/L。粒径大于0.25 mm时,最佳固液比为20 g/L,温度的影响明显减弱。将Ca2+提取实验结果与XRD、SEM表征结合,发现废弃混凝土提取过程中SiO2惰性层的出现是限制Ca2+提取率进一步提高的重要原因。
Indirect Carbonation of Abandoned Concrete An important step in CO2 sequestration is to extract Ca2 + from concrete. The dissertation studied the extraction of Ca2 + from waste concrete. The effects of extraction solvent, concrete particle size, temperature and solid-liquid ratio on Ca2 + extraction were investigated. Different extraction solvents were compared and found that when HNO3 as a solvent Ca2 + extraction rate was highest, followed by CH3COOH, HCOOH and H2SO4. Reducing the particle size of concrete can effectively improve the extraction rate of Ca2 +. For concrete with particle size less than 0.15 mm, the extraction rate of Ca2 + increases with the increase of temperature, and the optimum solid-liquid ratio is 40 g / L. The particle size of more than 0.25 mm, the best solid-liquid ratio of 20 g / L, the temperature significantly weakened. The results of Ca2 + extraction combined with XRD and SEM characterizations show that the appearance of inert SiO2 layer during the extraction of waste concrete is an important reason to limit the extraction rate of Ca2 +.