Adsorption of Cadmium Ions from an Aqueous Solution on a Highly Stable Dopamine-Modified Magnetic Nano-Adsorbent

Table 3 Comparison of the maximum adsorption capacities of Fe₃O₄@PDA with some adsorbents cited in the literature

Adsorbents		q_m (mg/g)	pH	C_{0 (Cd)} (mg/L)	References
Nano-hydroxyapatite nanorods		92	5.8	100–500	[1]
Nano-hydroxyapatite chitosan composites		122	5.8	100–500	[1]
Fe₃O₄@SiO₂@m-SiO₂–NH₂		884.906	6	20–843	[20]
Fly ash/chitosan (A-FA/Ch) composite		87.72	8	25–600	[21]
Surface-modified Eucalyptus seeds by sulfuric acid (SMES-S)		71.15	5	20–100	[52]
Surface-modified Eucalyptus seeds by hydrochloric acid (SMES-H)		64.16	5	20–100	[52]
Nano zero-valent iron particles		769.2	–	25–450	[57]
Biopolymeric sorbent: sporopollenin		2.23	7	0–250	[59]
Poly (sodium acrylate)–graphene oxide		225.7	6	20–600	[60]
Zero-valent iron-coated biochars (magnetic ones)	MBC₁	38.00	5	50–600	[61]
Zero-valent iron-coated biochars (magnetic ones)	MBC₂	41.25	5	50–600	[61]
Multiwalled carbon nanotubes (MWCNTs)	Raw-MWCNT	1.260 ± 0.02	8	0.1–5	[62]
	O-MWCNT	22.39 ± 0.36
	E-MWCNT	21.67 ± 0.40
Sawdust of Pinus sylvestris		15.27	4	1–50	[63]
		19.08	5
		6.72	7
Mustard husk		42.85	6	1–5	[64]
Mercaptoacetic-acid-modified orange peel (MOP)		136.05	7	50–1000	[65]
Polydopamine-modified Fe₃O₄		21.58	7	3–30	This study