矿物对金属离子的竞争吸附实验研究

EXPERIMENT ON THE COMPETETION ADSORPTIONS OF METAL IONS ONTO MINERALS

CaCO_3、石英、针铁矿、三水铝矿、高岭土、蒙脱石、水云母等矿物对Ag+、Cu2+、Zn2+、Ni2+、Cd2+、Pb2+和Cr3+金属离子的竞争吸附实验研究表明，在近中性低离子强度溶液中，矿物单位表面积吸附金属离子的大小顺序是：CaCO3＞石英＞水云母＞高岭土＞蒙脱石＞针铁矿＞三水铝矿。这些矿物可分成3组：第一组的矿物有石英、针铁矿和高岭土等1：1层硅酸盐矿物及其他氧化物；第二组为三水铝矿、水镁石和蒙脱石等2:1层硅酸盐矿物；第三组是碳酸盐、硫酸盐、磷酸盐等含氧盐矿物。它们对于金属离子的吸附反应；＞SO－＋Mn+=＞SOM(n-1)+(n=1,2,3）有如下的显平衡常数KM与矿物介电常数ε的关系式：（1）lgk1M=7．813－26.15／ε（2）lgK2M－9．030－26.15／ε（3）lgK3M=11．65－26．

The study on the competetion adsorptions shows that the order of metal ions adsorbed onto oxide and silicate minerals in near-neutral solution with low ionic strength are as follows (in mol /nm2): CaCO3 > quartz> hydromuscovite > kaolinite > Ca-montmorillonite> goethite> gibbsite. These minerals can be divided into three groups according to their appearance equilibrium constants KM of the adsorption reaction, which are the function of the dielectric constants ε of the absorbent absorbent mierals.The relationships between the constants KM and the ninteral dielectric constants ε are as follows: lgk1M= 7．813－26.15／εlgK2M－9．030－26.15／εlgK3M=11．65－26．15／εfor the adsorption reaction： > SO－＋ Mn+=> SOM(n-1)+(n=1,2,3）The first group includes quartz, goethite, 1:1 Phyllosilicates and other oxide minerals;the second group comtains gibbsite,bruite and 2:1 phyllosilicates, the third group includes carbonate, sulphurate and phosphorate minerals. The appearance reaction constants have a variation of magnitute±0.5 for different metal ions with same mineral.