The adsorption of Cu(II) ions on bentonite--a kinetic study

The kinetics of sorption of Cu(2+) on a Saudi clay mineral (bentonite) was investigated at 20+/-0.5 degrees C using different weights of the clay (0.5, 1.0, 1.5, and 2 g). Each weight represents a certain sample size. The order of the process appeared to be 1 with respect to the Cu(2+), and 112 with respect to the clay surface area. The rate was found to depend on internal diffusion.,which produced a decrease in the specific rate of sorption as a function of time. Sorption characteristics were described using two site Langmuir isotherms. The desorption experiments proved that Cu(2+) ions are chemisorbed on the bentonite surface. The maximum adsorption obtained was 909 mg Cu(2+)/g clay. This value is of great significance, as it is much higher than any reported one.