【摘要】 室温下(25℃±1℃)采用间歇法(batchmethod)模拟研究高岭石在pH5.5、pH4.5和pH3.5的HAC/NH4AC缓冲液中的溶解。实验结果表明:质子能够促进高岭石Al和Si的释放,且Al、Si的释放能力随反应液酸度的增加而增强,Al、Si溶解的一致性与酸度有关。pH5.5时,可能因Al的沉积而导致整个实验期间Al、Si释放表观不一致;pH4.5和pH3.5时,反应前期Al优先释放,而在反应后期Al、Si趋于一致。pH5.5、pH4.5和pH3.5的HAC/NH4AC缓冲液中高岭石溶解速率分别为:3.09×10-14mol/(m2·s)、6.31×10-14mol/(m2·s)和1.13×10-13mol/(m2·s)。HAC/NH4AC缓冲液中质子作用下高岭石溶解反应级数和速率常数分别为0.28和1.12×10-12。更多还原

【Abstract】 Dissolution of kaolinite was investigated in pH5.5, pH4.5 and pH3.5 HAC/NH4AC buffer solutions separately with the batch method at room temperature (25℃±1℃). The results showed release of Al and Si from kaolinite was enhanced significantly by proton, compared with that in deionized water. It decreased with increasing pH. Dissolution stoichiometry of kaolinite was related to pH. The process of kaolinite dissolution was apparently nonstoichiometric in pH5.5 due to Al-rich precipitation. Preferential Al-release was observed initially at pH4.5 and pH3.5, however, the release of Al and Si inclined towards stoichiometric after 936 h. The dissolution rates of kaolinite in pH5.5, pH4.5 and pH3.5 HAC/NH4AC were 3.09×10-14 mol/(m2·s), 6.31×10-14 mol/(m2·s), and 1.13×10-13 mol/(m2·s), respectively. The reaction order and rate constant of proton-promoted kaolinite dissolution were 0.28, 1.12×10-12, respectively.更多还原