Studies of Adsorption of Heavy Metals onto Spent Coffee Ground: Equilibrium, Regeneration, and Dynamic Performance in a Fixed-Bed Column

Table 3

External mass transfer and axial dispersion coefficients for heavy metal adsorption onto SCG.

Metal	(Scm^2/mol)	(m^2/s)	(m/s)		MSE
Cd^2+	108.13	1.71 × 10^−9	1.07 × 10^−5	1.62	0.017
Cu^2+	107.20	1.72 × 10^−9	1.08 × 10^−5	4.52	0.012
Pb^2+	142.00	1.89 × 10^−9	1.14 × 10^−5	7.00	0.017

The axial dispersion coefficient () was taken as constant at 3.53 × 10⁻⁶ m²/s.