2.5. Equilibrium experiments
In equilibrium experiments, all of the solution samples were adjusted
to optimum pH of 4. The solution samples for lead and copper were
respectively diluted to different concentrations from 10 mg/L to 400
mg/L. And then, 50 mL of solution sample and 0.1 g Ca-alginate dried
beads were tested under the rotary shaker at 140 rpm for different contact
times from 30 min to 48 h. The equilibrium time would be determined
from FAAS according to the results of solution concentration
before and after experiment. The kinetic models and Langmuir isotherm
models for lead and copper adsorptions would be discussed in details in
following sections.