Table 4.

Parameters of isotherm for methylene blue dye treatment using modified rice straw at different pH values (2–10) and T = 303 K.

Model	Parameters	pH  2	pH  4	pH  6	pH  8	pH  10
Langmuir	Kl × 10–4	0.998	1.490	4.404	7.663	43.583
	qm × 104	4.22	6.36	8.58	9.665	9.56
	R2	0.987	0.997	0.994	0.999	0.999
Freundlich	KF × 10–2	5.911	1.888	1.795	4.951	6.515
	n	4.49	3.39	4.05	10.2	16.36
	R2	0.965	0.898	0.731	0.684	0.559
Temkin	KT × 10–8	0.006	0.012	1.784	4.852	14.462
	b × 10–7	4.198	2.519	0.251	3.046	5.038
	R2	0.932	0.935	0.754	0.701	0.558