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采用间歇法(batch method)模拟研究高岭石在柠檬酸、草酸和苹果酸溶液中的长期溶解效应。研究表明:柠檬酸、草酸和苹果酸三种低分子量有机酸能显著促进高岭石的溶解,它们对高岭石的溶解能力都是随其浓度的升高而增强,其溶解能力的顺序为:草酸>柠檬酸>苹果酸;苹果酸导致了高岭石Si的优先释放,而柠檬酸和草酸则导致了Al的优先释放。对于柠檬酸而言,高岭石一般在反应中期趋于同步溶解,且其同步性随其浓度的升高而增强。对于草酸而言,高岭石通常是在反应后期才趋于同步溶解;而对于苹果酸而言,1 mmol L-1时,在整个实验期间,高岭石都是非同步溶解;5 mmol L-1和10mmol L-1时,高岭石是以Al/Si小于1的一定速率比溶解;20 mmol L-1时,高岭石是在反应96 h后才表现为趋于同步溶解。
A batch method was used to simulate the long-term dissolution of kaolinite in citric acid, oxalic acid and malic acid solutions. The results showed that three kinds of low molecular weight organic acids, citric acid, oxalic acid and malic acid, can significantly promote the dissolution of kaolinite. The dissolving ability of kaolinite to all kaolins is enhanced with the increase of their concentration. The order of their dissolving ability is : Oxalic acid> citric acid> malic acid; malic acid led to the preferential release of kaolinite Si, while citric acid and oxalic acid led to the preferential release of Al. In the case of citric acid, kaolinite tends to dissolve synchronously in the middle of the reaction, and its synchronicity increases with increasing concentration. For oxalic acid, kaolinite usually tends to dissolve synchronously in the late stage of the reaction. For malic acid, kaolinite dissolves non-synchronously at 1 mmol L-1 throughout the experiment. 5 mmol L- 1 and 10 mmol L-1, kaolinite was dissolved at a certain rate of Al / Si less than 1. When kaolin was 20 mmol L -1, kaolinite showed synchronous dissolution until 96 h.