溶液条件对磷酸钙沉淀法回收磷的影响  

Effects of solution conditions on the precipitation of calcium phosphate for recovery

作　　者：高英[1] 叶荣[1] 宋永会[2] 袁鹏[2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国环境科学研究院水污染控制技术研究室,北京100012

出　　处：《安全与环境学报》2007年第3期58-62,共5页Journal of Safety and Environment

基　　金：国家自然科学基金项目(50678162);国家高层次留学人才回国资助项目(2005118);国家留学人员科技择优资助项目(200499)

摘　　要：磷酸钙沉淀法是从富磷废水中回收磷的主要工艺。为优化工艺,利用批次沉淀实验、热力学模拟计算和X-射线衍射法研究了溶液pH值、初始Ca/P物质的量比、碳酸根和腐殖质浓度对磷酸钙沉淀的影响。结果表明,初始Ca/P物质的量比为1.67,磷酸根浓度为0.35mmol/L、0.70mmol/L、1.4mmol/L时,能够实现快速反应的最小pH值分别为9.5、9.0和8.0。最终沉淀产物以热力学上最稳定的羟磷灰石形态存在。pH=8.0时,碳酸根和腐殖质会抑制磷酸钙沉淀反应;但pH>9.0时,它们对反应的影响甚小。提高溶液pH值和Ca/P物质的量比均可降低干扰,有效提高沉淀反应效率。调控溶液pH值和Ca/P物质的量比是利用磷酸钙沉淀工艺从废水中回收磷的关键。The paper introduces the investigation of the effects of solution conditions on the precipitation of calcium phosphate for recovery from wastewater with batch experiments, thermodynamic calculations and X-ray diffraction. The solution conditions include the solution pH value, the initial Ca/P molar ratio, and the concentrations of carbonate and humic substances. Our study results indicate that when the phosphate concentrations were 0.35 - 1.4 mmol/L and the initial Ca/P molar ratios - 1.67, the precipitation reactions might proceed very quickly with suitable solution pH supplied. When the initial Ca/ P molar ratio was 1.67 and the phosphate concentrations were 0.35 mmol/L, 0.70 mmol/L and 1.4 mmol/L, the minimum pH values for significantly rapid precipitation of calcium phosphate would be 9.5, 9.0 and 8.0, respectively. The final product tends to a thermodynamically highly stable phase, that is, hydroxyapatite. However, at solution pH 8.0, carbonate and HS would begin to inhibit the precipitation of calcium phosphate, and their influence would be getting weaker when the solution pH 〉9.0. Both the increase of solution pH value and that of initial Ca/P molar ratio may help to increase the precipitation efficiency, therefore contributing to overcoming the inhi- bition of carbonate and humic substances on the precipitation. Thus, it can be seen that, both the solution pH value and the initial Ca/P molar ratio are two controlling factors for phosphorus recovery from wastewater. Nevertheless, to keep the precipitate purity of calcium phosphate, the solution pH value and initial Ca/P molar ratios should be moderately kept throughout the precipitation process.

关 键 词：环境工程 磷酸钙 Ca/P物质的量比 PH值 磷回收 沉淀 碳酸根 腐殖质 

分 类 号：X703.1[环境科学与工程—环境工程]