Table 1.

Experimental characteristic rate constants found with spectrophotometry and the OA technique and their comparison with existing data (confidence level 0.95).

Conditions (initial iron concentration)		Characteristic rate constant k−1, s−1 ×105	Characteristic rate constant ${\tilde{k}}_{-1}$, corrected for H2SO4 concentration, s−1 ×105
cFe = (1 − 100) × 10−8 mol l–1 pH 0.5, (0.3 mol l−1 H2SO4), 20 °C (thermal lensing) [44]		5.0	6.5
cFe = (1 − 100) × 10−6 mol l–1 1 mol l−1 HCl, 25 °C (spectrophotometry) [34,45]		7.4	–
cFe = (1 − 100) × 10−6 mol l–1 0.5 mol l−1 H2SO4, 25 °C (spectrophotometry) [32,33]		7.5	7.5
cFe = (1 − 100) × 10−6 mol l–1 1 mol l−1 H2SO4, 25 °C (spectrophotometry) [46]		7.33	7.3
cFe = 3.2 × 10−2 mol l−1 pH-1.4 (13.1 mol l−1 H2SO4) 25 °C	This study, spectrophotometry (n = 18)	39 ± 9	7 ± 2
	This study, OA technique (n = 3)	40 ± 2	7.8 ± 0.4