Table 3.

Adsorption capacity of different adsorbents for Cd2+ and Cr3+ adsorption adsorbent.

Cd2+			Cr3+
Adsorbent	Adsorption capacity (mg/g)	Reference	Adsorbent	Adsorption capacity (mg/g)	Reference
Orange peel–Fe2O3	71.43	[76]	carrot residues	45.09	[77]
Prunus avium leaves	45.45	[91]	spirogyra spp	30.21	[79]
Kiwi cortex	15.9	[88]	modified lignin	25	[81]
Unmodified rice straw	13.9	[92]	Untreated pinussylvestris bark	8.69	[82]
Coffee grounds	15.65	[83]	Treated pinussylvestris bark	9.77	[82]
Activated carbon	10.3	[84]	Sphagnum moss peat	29	[85]
Agave bagasse	14	[89]	modified and non-modified carbon nanotubes	18	[7]
commercial activated carbon	14.93	[78]	Grain-less stalk of corn	7.3	[90]
RPG	99.85	This work	RPG	39.86	This work