where k1 is the rate constant of preudo-first-order adsorption
(1/min), qt and qe are the amount adsorbed at time t and equilibrium
(mg/g). According to the adsorption kinetic parametersreported in Table 1, the values of correlation (r2) are relatively
low for most of the adsorption data at different initial concentrations,
and the experimental amount adsorbed at equilibrium qe(exp)
do not agree well with the calculated ones. This shows that the
adsorption process may not be the correct fit to the first-order rate
equation. Another kinetic model is pseudo-second-order model,
which is expressed as: