粘土矿物对海水中主要营养盐的吸附研究

STUDY OF MAIN NUTRIENTS ADSORPTION ON CLAYS IN SEAWATER

对海水中磷酸盐和硝酸盐在粘土矿物上的吸附行为的研究发现，海水体系中高岭土对磷酸盐的吸附能力大于蒙脱土，其原因为，粘土颗粒的表层铝／硅结构比是控制磷酸盐吸附的主要因素，其中铝含量越高，吸附能力越大。考察pH、粘土酸改性处理等因素对吸附作用的影响，结果表明，pH＜8．5的磷酸盐吸附pH曲线呈峰形，其吸附作用以阴离子交换为主；pH＞8．5时磷酸盐的吸附作用以沉淀吸附为主。酸改性蒙脱土可提高吸附磷酸盐的能力，对高岭土则恰好相反。对硝酸盐的吸附研究表明，在通常条件下其在粘土矿物上的吸附百分率均在6％以下，可以忽略粘土矿物对它的吸附作用。

The adsorption of main nutrients in seawater, phosphate and nitrate, on clays is studied. A new experimental phenomenon that phosphate adsorption capability on kaoline is greater than that on montmorillonite, which is explained as that the alumina-silica ratio of clays is the dominant factor for phosphate adsorption and the more the alumina content in clay surface layer, the stronger the phospliate adsorpt ion. The effects of pH and acid-modification for clays on adsorption are also examined. The pH curves of phosphate adsorption are peak-shaped and the dominant adsorption is considered as anion exchange reactions in pH < 8.5. When pH > 8.5the precipitation adsorption is dominant. The acid-modification for montmorillonite tan enhance Phosphate adsorption capability on it, but kaoline is just opposite from montmorillonite, i. e. acid-modification leading to the decrease of Phosphate adsor ption. The study of nitrate adsorption on clays shows that tke adsorption centage is generally < 6%, and so its adsorption on clays can be neglected.