Sorption capacity (q_max) and partition coefficient (PC) for MO by some natural, modified and synthetic materials in comparison with the An/CNT composite of the present study: q_max obtained from the Langmuir constant, PC = q_max/residual MO concentration.

Adsorbent	Initial MO concentration (mg L−1)	Residual MO concentration (μM)	Adsorption capacity qmax (mg g−1)	pH/T (K)	Partition coefficient (mg g−1 μM−1)	Reference
Bottom ash	32.7	1.4b	3.62	3.0/333	2.6b	60
De-oiled soya	32.7	0.2b	16.66	3.0/333	83.3b	60
Activated clay	80	—	16.78	7.0/313	—	61
Maghemite/chitosan nano-composite films	20	—	29.41	3.0/330	—	62
Bentonite	—	—	33.8	4.5/298	—	63
Organic matter rich clays (OMRC)	100	10.4	41.67	2.0/298	4.01	41
Calcinated organic matter rich clays (COMRC)	100	39.6	34.48	2.0/298	087	41
Functionalized-CNTs with 3-aminopropyltriethoxysilane loaded TiO2 nanocomposites	5	0.92a	42.85	6.5/298	46.52a	39
Multi-walled carbon nanotubes	—	—	52.86	2.3/333	—	8
Activated carbon (AC)	10	116.12a	78.7	4.5/300	0.48a	11
Multi-walled carbon nanotubes (MWCNTs)	10	95.3a	106.3	4.5/300	0.99a	11
Multi-walled carbon nanotubes/activated carbon (MWCNTs/AC)	10	35.99a	196.1	4.5/300	5.31a	11
FeOOH/carbonized bacterial cellulose (FeOOH/CBC) nanocomposite	50	5.8b	107.7	6.0/333	18.6b	64
Zn–Al layered double hydroxides intercalated with surfactant (DS-Zn/Al LDHs)	30	1.8b	114.9	7.0/298	63.8b	65
CuMgAl layered double hydroxide (CuMgAl LDH)	20	1.2b	123.5	7.0/298	101.2b	66
Activated carbon/Fe3O4 nanoparticle composites (10Fe3O4/PAC-HNO3)	—	—	303.03	5.0/303	—	27
Powdered activated carbon modified by HNO3	—	—	384.62	5.0/303	—	27
MWCNTs/Fe3O4/PANI magnetic composite	150	189.41a	446.25	4.5/298	2.36a	67
An/CNT composite	100	2.11	416.7	3.0/298	197.5	Current study

^aThese data were derived from Ahlawat et al., 2020 (ref. 11) (Table 6) with the proper correction for the residual MO concentration.

^bThese data were derived from Grover et al., 2019 (ref. 65) (Table 3) with the proper correction for the residual MO concentration.