Assessment of Untreated Coffee Wastes for the Removal of Chromium (VI) from Aqueous Medium

Table 1

The pseudofirst-order and pseudosecond-order adsorption rate constants.

Kinetic model	Parameters	T (°K)
		298	303	313	323
	qe, exp (mg g^−1)	35.52	35.02	34.66	33.98
Pseudofirst-order	qe, cal (mg.g^−1)	29.64	24.80	22.74	16.86
	k1 (min^−1)	0.0521	0.0463	0.0440	0.0341
	R^2	0.943	0.964	0.974	0.863
	χ^2	0.1026	0.0510	0.0331	0.1153
Pseudosecond-order	qe, cal (mg.g^−1)	37.41	36.68	36.18	35.15
	k2 (g mg^−1min^−1)	0.0037	0.0041	0.0045	0.0053
	R^2	0.999	0.999	0.999	0.999
	χ^2	0.0014	0.0009	0.0008	0.0010
	h	5.18	5.52	5.89	6.55