Table 1.

Comparison of Pb(II) and Cd(II) ions adsorption capacity (mmol g⁻¹) on SR-PAA and equilibrium adsorption time with various other adsorbents.

Adsorbents	Qe (mmol g−1)		Contact time (min)a	T (°C)	pH	Reference
	Pb(II)	Cd(II)
Raw maize stover	0.09	—	60	25	5	39
HNO3 treated maize stover	0.13	—	60	25	5	39
NaOH modified agaricus bisporus	0.42	—	—	25	5.5	40
Orange peel biochar (OP-BC)	0.13	—	15	25	5–6	41
Amino siloxane oligomer-linked graphene oxide	1.51	—	300	30	4.0–5.0	42
Natural Artemia CS	1.54	—	2	25	6.4 ± 0.1	43
Snowflake-shaped zno@sio2@Fe3O4/C	0.46	—	180	—	7	44
MWCNT-PDA hybrid aerogelsb	1.69	—	600	25	6	45
Biochars derived from Switchgrass (SW450)	0.05	—	1440	22		46
Fe3O4@PMAA yolk–shell microspheres	2.48	—	240	25	6	47
Biochars originated from Grape stalks	2.87	—	1440	22 ± 1	5	48
Biochars originated from wheat straws	1.32	—	1440	22 ± 1	5	48
Biochars originated from grape hulls	0.86	—	1440	22 ± 1	5	48
Cotton derived porous carbon (CDPC)	0.10	0.07	overnight	25	5 (Pb), 6(Cd)	29
Cotton derived porous carbon oxide (CDPCO)	0.54	0.36	overnight	25	5 (Pb), 6(Cd)	29
Chestnut bur	0.20	0.15	360	20–25	4	49
Functionalized yeast cells	0.56	0.38	—	25	5	50
Mercapto-modified coal gangue (CG-SH)	0.94	0.76	>250(Pb), >200(Cd)	25	5.5	51
Fe(III)—pomegranate peel carbon		0.22	120	—	6.36	52
Sunflower head carbon (SHC)		0.25	180	—	6	53
Sunflower stem carbon (SSC)		0.32	180	—	6	53
Posidonia oceanica biomass		0.23	30	—	6	54
Magnesium chloride-modified Lentinula edodes		0.46	120	—	5	55
Cu3(BTC)2–SO3H		0.79	10	—	6	56
SR	0.33	0.03	60	—	6	This work
SR-PAA	2.03	1.43	20	—	6	This work

^aEquilibrium adsorption time.

^bGraphene/polydopamine modified multiwalled carbon nanotube hybrid aerogels.