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

Table 2

Langmuir and Freundlich isotherm data and partition coefficients for TiO₂samples A and C at 1, 5, and 24 hours. 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.

		TiO2 Sample A			TiO2 Sample C
		1 h	5 h	24 h	1 h	5 h	24 h
Langmuir	$R^2$	$0.94\text{–}0.99$	0.99	$0.94\text{–}0.99$	0.73-0.74	$0.17\text{–}0.24$	0.97-0.98
	$Q_o$	28.4 (2.8)	27.5 (4.9)	35.2 (5.3)	2.2 (0.0)	9.4 (1.5)	8.0 (0.2)
	$b$	0.37 (0.30)	0.37 (0.16)	0.91 (0.44)	−0.06 (0.01)	0.01 (0.00)	0.04 (0.01)
Freundlich	$R^2$	$0.87\text{–}0.91$	$0.55\text{–}0.77$	$0.91\text{–}0.93$	$0.64\text{–}0.87$	$0.55\text{–}0.61$	$0.77\text{–}0.91$
	$K_f$	11.5 (2.8)	13.5 (1.0)	15.3 (1.8)	0.5 (0.0)	0.6 (0.2)	1.0 (0.1)
	$n$	4.55 (0.51)	6.53 (2.48)	3.91 (1.72)	3.35 (0.12)	2.43 (0.50)	2.72 (0.00)
Dye conc.
$K_d$	A:−200 mg l^−1	278	423	1085	1.3	1.3	2.7
	C:−240 mg l^−1
	640 mg l^−1	13	12	51	1.0	2.4	1.3