Calculated isotherm parameters and correlation coefficients (R²) of RR24 adsorption isotherm models onto the biochars.

Model	Adsorbents
	SBB	SBB-ZnO3	CRHB	CRHB-ZnO3
Langmuir
q e,cal (mg g−1)	77.41	110.36	64.71	82.15
K L (L mg−1)	0.0155	0.0135	0.0038	0.0007
R 2	0.9975	0.9925	0.9972	0.9996
Freundlich
K F (mg g−1) (mg L−1)n	6.5452	9.2968	1.2510	4.6569
n	2.3315	2.3288	1.4342	1.9605
R 2	0.9947	0.9902	0.9697	0.9497
Sips
q e,cal (mg g−1)	80.64	107.07	63.54	79.66
b	0.0272	0.0209	0.0030	0.0048
n	1.5931	1.2114	0.8950	0.8862
R 2	0.9912	0.9895	0.9887	0.9808