Table 2. Isotherm Model Parameters Obtained for Co(II) Ion Adsorption onto the Silica–Kraft Lignin Sorbent.

	Co(II)
isotherm model (parameter, unit)	22 °C	40 °C	60 °C
Langmuir
qm, mg/g	18.55	15.20	4.79
KL, L/mg	0.098	0.095	0.379
R2	0.9908	0.9909	0.9908
Freundlich
KF, mg/g	1.60	1.49	1.17
1/n	0.529	0.530	0.480
R2	0.9564	0.9418	0.7994
Temkin
bT, kJ/mol	0.82	1.02	2.83
KT	1.906	2.026	4.600
R2	0.9528	0.9741	0.9258