| 砷酸钙化合物的溶解度及其稳定性随pH值的变化 |
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| 引用本文： | 朱义年,张华,梁延鹏,刘辉利,张学洪. 砷酸钙化合物的溶解度及其稳定性随pH值的变化[J]. 环境科学学报, 2005, 25(12): 1652-1660 |
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| 作者姓名： | 朱义年 张华 梁延鹏 刘辉利 张学洪 |
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| 作者单位： | 桂林工学院资源与环境工程系,桂林,541004;桂林工学院资源与环境工程系,桂林,541004;桂林工学院资源与环境工程系,桂林,541004;桂林工学院资源与环境工程系,桂林,541004;桂林工学院资源与环境工程系,桂林,541004 |
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| 基金项目： | 国家自然科学基金（No.40263001）;教育部科学技术研究重点项目（No.2003-77-03102）;广西高校百名中青年学科带头人资助计划（No.2003-97） |
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| 摘 要： | 通过混合沉淀和溶解实验详细研究了pH值和Ca/As摩尔比对石灰沉淀法处理高浓度含砷废水的影响.沉淀后溶液中的As浓度随pH值的变化趋势与混合液的Ca/As摩尔比有关,在Ca/As=1·50和1·67时,沉淀后溶液中的As浓度在pH=7附近达到最低,然后随pH值的升高而呈现出增大的趋势;在Ca/As=2·00和4·00时,沉淀后溶液中的As浓度随pH值的升高而降低,且2种Ca/As摩尔比条件下的实验结果基本一致.混合沉淀过程中生成的砷酸钙化合物的组成与结构取决于溶液的Ca/As摩尔比和pH值.在低pH值和低Ca/As摩尔比条件下形成的沉淀物要比在高pH值和高Ca/As摩尔比条件下形成的沉淀物的颗粒要大,而且结晶程度要好.在Ca/As摩尔比为1·0~4·0和不同pH值条件下,主要生成Ca_3(AsO_4)_2·3H_2O、Ca_3(AsO_4)_2·2·25H_2O、Ca_5(AsO-4)_3OH和Ca_4(OH)-2(AsO_4)2·4H_2O,溶度积分别等于10~(-21·14)、10~(-21·40)、10~(-40·12)和10~(-27·49).
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| 关 键 词： | 石灰沉淀 砷酸钙 溶解度 稳定性 pH值 |
| 文章编号： | 0253-2468(2005)12-1652-09 |
| 收稿时间： | 2005-04-21 |
| 修稿时间： | 2005-10-09 |
Dependence of solubility and stability of calcium arsenates on pH value |
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| ZHU Yinian,ZHANG Hu,LIANG Yanpeng,LIU Huili and ZHANG Xuehong. Dependence of solubility and stability of calcium arsenates on pH value[J]. Acta Scientiae Circumstantiae, 2005, 25(12): 1652-1660 |
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| Authors: | ZHU Yinian ZHANG Hu LIANG Yanpeng LIU Huili ZHANG Xuehong |
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| Affiliation: | Department of Resources and Environmental Engineering, Guilin Institute of Technology, Guilin 541004,Department of Resources and Environmental Engineering, Guilin Institute of Technology, Guilin 541004,Department of Resources and Environmental Engineering, Guilin Institute of Technology, Guilin 541004,Department of Resources and Environmental Engineering, Guilin Institute of Technology, Guilin 541004 and Department of Resources and Environmental Engineering, Guilin Institute of Technology, Guilin 541004 |
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| Abstract: | The effect of pHand Ca/As ratio on the lime precipitation of arsenic-containing wastewater was studied in detail by both precipitation and dissolution experiments. For the precipitation under Ca/As=1.5 and 1.67, the residual arsenic concentration reached the lowest value at pH 7.0, and then increased slowly with the increasing pHvalues. The residual arsenic concentration after precipitation under Ca/As=2.0 and 4.0 decreased quickly with the pHincrease. There was no great difference between the experimental results for Ca/As=2.0 and 4.0. The composition and structure of the calcium arsenate compounds, which precipitated from the mixing of As solution with Ca(OH)2 slurry, depended on the pHand the Ca/As molar ratio. The particle size of the solids precipitated at high pHand high Ca/As ratio was much finer than for the low-pHand low-Ca/As precipitated solids. Ca3(AsO4)2·3H2O, Ca3(AsO4)2·2.25H2O, Ca5(AsO4)3OH and (Ca4(OH)2(AsO4)2·4H2O) were identified in the experiment over a wide range of pHand for Ca/As molar ratios between 1.0 and 4.0. Based on the analytical results,their solubility products were calculated as Ksp of 10-21.14, 10-21.40, 10-40.12 and 10-27.49, respectively. |
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| Keywords: | lime precipitation calcium arsenates solubility stability pH value |
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