TABLE 2.

Comparison of Co retention of prepared nanocomposites and the previous studies in the literature.

Sorbent	Retention capacity, (mg/g)	Condition				Ref
		pH	Temp K	Ionic strength	m/v g/L
Iron oxide/CNTs	2.88	6.4	293	0.01 M	0.50	Wang et al. (2011)
CNTs	2.60	9	293	—	5.00	Stafiej and Pyrzynska (2007)
Activated carbon	1.2	6	303	—	180.0	Sulaymon et al. (2009)
Magnetite/graphene oxide	12.98	6.8	303	0.01 M	0.40	Liu et al. (2011)
β–Cyclodextrin/graphene oxide	72.43	6	303	0.01 M	0.10	Song et al. (2013)
Titanate/graphene oxide	81.3	6	293	0.01 M	0.17	Wang et al. (2015)
Fe3O4/bentonite	18.76	8	293	—	0.10	Hashemian et al. (2014)
O-CNTs	15.27	6.4	323	—	0.50	This work
Fe-CNTs (48.2%)	20.32	6.4	323	—	0.50	This work
Ti-CNTs (90.2%)	29.80	6.4	323	—	0.50	This work