CAJ | 학술논문

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2h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。
사용린산염용액화방해석지간적반응득도방해석거제수중린산염후적산물，즉린산염개성방해석，통과실험대비분석료방해석화린산염개성방해석대수중린산염적거제동역학，병고찰료린산염개성방해석거제수중린산염적각충영향인소。린산염개성방해석대수중린산염적거제능력명현우우방해석。당반응시간위2h시，실험조건하린산염개성방해석대수중린적거제솔체도72%，이방해석대린적거제솔부위35%。당pH위5~7시，린산염개성방해석대수중린산염적거제능력교고；당pH유7증가도10 h，대린산염적거제능력략미하강；당pH유10증가도12 h，대린산염적거제능력급극하강。린산염개성방해석대수중린산염적단위거제량수초시린질량농도적증가이증가。과고적초시린질량농도회도치린산염개성방해석대수중린산염적거제솔과저。린산염개성방해석대수중린산염적거제능력수반응온도적승고이증가。린산염개성방해석대수중린산염적거제동역학가이교호지채용준이급동역학모형가이묘술。수중공존적개리자유리우린산염개성방해석대린산염적거제，이수중공존적탄산경근리자억제료린산염개성방해석대린산염적거제。린산염개성방해석거제수중린산염적주요궤제시린산개침정작용。린산염개성방해석불부회위린산개침정반응적이질성핵제공핵심，촉진린산개침정적형성，이차당수처우대방해석불포화상태시회용해석방출가용성개，위린산개침정적형성제공개원。상술결과표명，방해석거제수중린산염후적산물가이피재차용우수중린산염적거제，병차대린산염적거제효과우우원시적방해석。
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 as substrate for the heterogeneous nucleation of calcium phosphate. The presence of Ca2+ions in aqueous solution represented a further source of Ca2+ions that were available for the precipitation of calcium phosphate, thus resulting in an increase in phosphate removal efficiency of phosphate-modified calcite. Coexisting HCO3- in aqueous solution was unfavorable for the removal of phosphate by phosphate-modified calcite. As a general conclusion, the calcite-phosphate reaction product can be reused to remove phosphate from aqueous solution, and it is a more effective media for the removal of phosphate than the original calcite.