| 摘要: |
| 于1990年2月在青岛鲁迅公园采得海水样品；1989年5月在南京采得伊利石样品，在苏州采得高岭石样品；1990年3月实验室合成针铁矿和δ－MnO2样品。用振荡平衡实验、离心分离方法和光度分析方法测定3种电解质溶液（NaCL溶液、NaCl-ChCl2溶液和海水）中磷酸盐在上述4种固体粒子上的交换率-PH曲线。测定结果表明，海水中磷酸盐在固体粒子上的交换率-PH曲线为V形，并建立阴离子液-固界面作用的交换率-PH公式；半定量地讨论V形交换率-PH曲线的形成机理，酸性溶液中，海水中腐殖酸和硫酸盐与磷酸盐竞争固体粒子上的作用点位，降低磷酸盐的液-固界面作用；碱性溶液中磷酸盐通过钙（Ⅱ）与固体粒子形成三元表面络合物，钙（Ⅱ）促进磷酸盐的液-固界面作用。海水中的钙（Ⅱ）、腐殖酸和硫酸盐是影响磷酸盐液-固界面作用的主要组分，酸性溶液中腐殖酸和硫酸盐降低磷酸盐在固体粒子上的交换作用，碱性溶液中钙（Ⅱ）会增加磷酸盐在固体粒子上的交换作用。 |
| 关键词: 磷酸盐交换 V形交换率-pH曲线 三元表面络合物 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，4890275号 |
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| ANION EXCHANGE OF PHOSPHATE ON SOLID PARTICLES IN SEAWATER—V-SHAPED E%-pH CURVES OF PHOSPHATE EXCHANGE ON SOLID PARTICLES IN SEA WATER |
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Zhao Hongbin1, Liu Liansheng2, Zhang Zhengbin2
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1.Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023;2.Institute of Marine Chemistry,Ocean University of Qingdao,Qingdao 266003
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| Abstract: |
| This study was focused on the effect of pH and soluble components, Ca(II) especially, of seawater on adsorption of phosphate on solid particles. The seawater was collected at Luxun Park in Qingdao in February 1990. Goethite and δ-MnO2 were synthesized in March 1990. Illite was obtained from Nanjing in May 1989, and kaolinite from Suzhou at the same time. Adsorption equilibrium was achieved by shaking, solid-liquid separation by centrifugation, and spectrophotometric analysis was used to determine adsorption of phosphate on the above solid particles. The electrolytes were NaCl solution, NaCl-CaCl2 solution and seawater. In the experiment, in NaCl solution, adsorption of phosphate on the solid particles as a function of pH showed a peaked curve. The species of phosphate and the electrical double layer of the solid particles were mainly responsible for this behavior. However, in NaCl-CaCl2 solution and seawater the curves of adsorption of phosphate on the solid particles versus pH had two peaks like a V. Accordingly, adsorption of phosphate on the solid particles increased in the presence of Ca(II) in alkaline solution bemuse a ternary surface complex of phosphate-Ca-solid particle was developed. But phosphate adsorption decreased in an acidic solution due to the competitive ion exchange of humic acid and sulfate in seawater. Taking into account the effects of pH, Ca(II), humic acid and sulfate and applying the concepts of ternary surface complex and competitive ion exchange, an equation of adsorption of phosphate on solid particles was proposed and applied to describe the above observations. In conclusion, ion-exchange of phosphate on solid particles decreases in an acidic solution with humic acid and sulfate, but increases in an alkaline solution with Ca(II). |
| Key words: Phosphate exchange, V-shaped E%-pH curve, Ternary Surface complex |
