摘要
使用磷酸盐溶液和方解石之间的反应得到方解石去除水中磷酸盐后的产物,即磷酸盐改性方解石,通过实验对比分析了方解石和磷酸盐改性方解石对水中磷酸盐的去除动力学,并考察了磷酸盐改性方解石去除水中磷酸盐的各种影响因素。磷酸盐改性方解石对水中磷酸盐的去除能力明显优于方解石。当反应时间为2 h时,实验条件下磷酸盐改性方解石对水中磷的去除率达到72%,而方解石对磷的去除率仅为35%。当pH为5～7时,磷酸盐改性方解石对水中磷酸盐的去除能力较高;当pH由7增加到10 h,对磷酸盐的去除能力略微下降;当pH由10增加到12 h,对磷酸盐的去除能力急剧下降。磷酸盐改性方解石对水中磷酸盐的单位去除量随初始磷质量浓度的增加而增加。过高的初始磷质量浓度会导致磷酸盐改性方解石对水中磷酸盐的去除率过低。磷酸盐改性方解石对水中磷酸盐的去除能力随反应温度的升高而增加。磷酸盐改性方解石对水中磷酸盐的去除动力学可以较好地采用准二级动力学模型加以描述。水中共存的钙离子有利于磷酸盐改性方解石对磷酸盐的去除,而水中共存的碳酸氢根离子抑制了磷酸盐改性方解石对磷酸盐的去除。磷酸盐改性方解石去除水中磷酸盐的主要机制是磷酸钙沉淀作用。磷酸盐改性方解石不仅会为磷酸钙沉淀反应的异质成核提供核心,促进磷酸钙沉淀的形成,而且当水处于对方解石不饱和状态时会溶解释放出可溶性钙,为磷酸钙沉淀的形成提供钙源。上述结果表明,方解石去除水中磷酸盐后的产物可以被再次用于水中磷酸盐的去除,并且对磷酸盐的去除效果优于原始的方解石。
Previous literatures have shown that calcite can be used to effectively remove phosphate from aqueous solution. In this study, the calcite-phosphate reaction product, i.e., phosphate-modified calcite was reused to remove phosphate from aqueous solution. The phosphate removal kinetics of natural calcite and phosphate-modified calcite were compared. The effect of various experimental conditions such as solution pH, initial phosphate concentration, temperature, Ca2＋ and HCO3- on phosphate removal by phosphate-modified calcite was investigated. The phosphate removal efficiency of phosphate-modified calcite was much higher than that of natural calcite. When the reaction time was 2 h, the phosphate removal efficiency of phosphate-modified calcite was 72%under the experimental conditions, which was much higher than that of natural calcite （35%）. The phosphate removal efficiency of phosphate-modified calcite was relatively high at pH 5-7, slightly decreased with increasing pH from 7 to 10, and significantly decreased with increasing pH from 10 to 12. The amount of phosphate removed by phosphate-modified calcite increased with increasing initial phosphate concentration. The phosphate removal efficiency of phosphate-modified calcite decreased with increasing initial phosphate concentration at a relatively high initial phosphate-phosphorus concentration （60-160 mg·L-1）. The phosphate removal efficiency of phosphate-modified calcite increased with increasing temperature. The phosphate removal kinetics of phosphate-modified calcite followed a pseudo-second-order kinetic model. The removal of phosphate by phosphate-modified calcite occurred predominantly via the precipitation of calcium phosphate according to two consecutive phases：first, the dissolution of calcite produced an increase in the Ca2＋concentration;then the Ca2＋ions reacted with the phosphate ions to form the precipitate of calcium phosphate. The precipitation of calcium phosphate took place at the surface of phosphate-modified calcite, which acted
出处
《生态环境学报》
CSCD
北大核心
2013年第9期1594-1601,共8页
Ecology and Environmental Sciences
基金
国家自然科学基金项目(50908142)
上海市科学技术委员会科研项目(10230502900)
上海高校青年教师培养资助计划项目ZZhy12012)
上海市教委重点学科建设项目(J50702)
关键词
磷酸盐改性方解石
去除
动力学
沉淀
phosphate-modified calcite
removal
kinetics
precipitation
