Studies of Dye Sensitisation Kinetics and Sorption Isotherms of Direct Red 23 on Titania

Table 3

Kinetic parameters for Direct Red 23 uptake onto TiO₂ samples A and C. For $R^2$, the range of values is shown from the replicate experiments. For other parameters, the data shown are averages with standard errors in parentheses.

		A			C
Co (mg l^−1)		163	330	650	163	330	650
1st order	$R^2$	$0.09\text{–}0.91$	$0.33\text{–}0.74$	$0.39\text{–}0.90$	$0.65\text{–}0.78$	$0.47\text{–}0.93$	$0.87\text{–}0.98$
	$K$	2.42 (2.41)	1.15 (0.55)	2.97 (1.29)	19.1 (19.1)	91.4 (47.9)	295 (470)
	$q_{\max \hspace{0.17em}}$	8.2 (0.1)	16.0 (0.6)	26.8 (2.8)	3.7 (3.7)	4.6 (0.3)	12.1 (9.5)
2nd order	$R^2$	0.99-1.00	0.99-1.00	0.99	$0.07\text{–}0.99$	$0.90\text{–}0.97$	$0.60\text{–}0.95$
	$K_2$	1.14 (1.75)	0.03 (0.03)	0.003 (0.002)	0.06 (0.06)	0.002 (0.002)	0.001 (0.001)
	$q_e$	8.1 (0.1)	16.5 (0.1)	28.3 (1.6)	5.5 (6.0)	7.9 (0.7)	12.9 (4.3)
	$h$	73 (112)	8 (10)	3 (2)	0.02 (0.04)	0.03 (0.01)	0.08 (0.05)