Table 1.

Equilibrium constant K_C and Gibbs free energy change ΔG⁰ at T = 298 K of the adsorption of nickel on chitosan in dependence on the initial concentration and the salt anion in solution. The contact time was 24 h.

Ni(NO3)2				NiSO4
C0	Ce	KC	ΔG0	C0	Ce	KC	ΔG0
(mg·L−1)	(mg·L−1)		(kJ·mol−1)	(mg·L−1)	(mg·L−1)		(kJ·mol−1)
1550	1350	0.15	4.73	1850	1420	0.30	2.96
1210	1100	0.10	5.70	1430	1040	0.38	2.43
927	824	0.13	5.15	1100	691	0.59	1.30
636	544	0.17	4.40	761	180	3.23	−2.90
315	244	0.29	3.06	417	100	3.17	−2.86
157	110	0.43	2.11	260	68.2	2.81	−2.56
31.7	9.63	2.29	−2.05	35.5	7.59	3.68	−3.23
15.8	2.64	4.98	−3.98	15.2	2.08	6.31	−4.56
3.15	0.166	17.98	−7.16	3.55	0.095	36.37	−8.90