Extraction of phosphorus from soil by membrane / ion exchange closed process

为发展酸碱溶液密闭萃取土壤中磷的工艺，对磷的萃取平衡和复极膜体系进行了研究。在pH 2和pH 11以上的条件下，无论使用的酸/碱是HCl、HNO3、HSO4、NaOH、KOH、NH3aq，都可以提取磷。在酸性条件下，用铝、钙、铁提取磷，在碱性条件下，用铝萃取磷。结果表明，复极膜体系是一种封闭的盐制酸/制碱工艺，可用于土壤中磷的提取。

For the development of the closed extraction process of phosphorus from soil with acid / alkali solution the extraction equilibrium of phosphorus and the bipolar membrane system were studied. Phosphorus was extracted under pH 2 and above pH 11 regardless of kind of acid / alkali used for the extraction, which were HCl, HNO3, H2SO4, NaOH, KOH, NH3aq. In the acid condition the phosphorus was extracted with Al, Ca, Fe and in the alkali condition phosphorus was extracted with Al. It was demonstrated that the bipolar membrane system, which was a closed process for producing both acid / alkali from salt, was useful for the extraction phosphorus from soil.