Gu Xueyuan, Evans Les J
Land Resource Science, University of Guelph, Guelph, ON N1G 2W1, Canada.
J Colloid Interface Sci. 2007 Mar 15;307(2):317-25. doi: 10.1016/j.jcis.2006.11.022. Epub 2006 Nov 21.
Illite samples from Fithian, IL were purified and saturated with Na(+) ions. The acid-base surface chemistry of the Na-saturated illite was studied by potentiometric titration experiments with 0.1, 0.01, and 0.001 M NaNO(3) solutions as the background electrolyte. Results showed that the titration curves obtained at different ionic strengths did not intersect in the studied pH range. The adsorption of Cd(II), Cu(II), Ni(II), Pb(II), and Zn(II) onto illite was investigated as a function of pH and ionic strength by batch adsorption experiments. Two distinct mechanisms of metal adsorption were found from the experimental results: nonspecific ion-exchange reactions at lower pH values on the basal surfaces and 'frayed edges' and specific adsorption at higher pH values on the mineral edges. Ionic strength had a greater effect on the ion-exchange reactions. The binding constants for the five heavy metals onto illite were determined using the least-square fitting computer program FITEQL. Linear free energy relationships were found between the surface binding constants and the first hydrolysis constants of the metals.
从伊利诺伊州菲西安采集的伊利石样品经过提纯并用钠离子进行了饱和处理。以0.1、0.01和0.001 M硝酸钠溶液作为背景电解质，通过电位滴定实验研究了钠饱和伊利石的酸碱表面化学性质。结果表明，在研究的pH范围内，不同离子强度下获得的滴定曲线不相交。通过批量吸附实验，研究了镉（II）、铜（II）、镍（II）、铅（II）和锌（II）在伊利石上的吸附情况，该吸附情况是pH值和离子强度的函数。从实验结果中发现了两种不同的金属吸附机制：在较低pH值时，在基面和“破损边缘”发生非特异性离子交换反应；在较高pH值时，在矿物边缘发生特异性吸附。离子强度对离子交换反应的影响更大。使用最小二乘法拟合计算机程序FITEQL确定了五种重金属在伊利石上的结合常数。发现表面结合常数与金属的一级水解常数之间存在线性自由能关系。
