Photooxidation Contribution Study on the Decomposition of Azo Dyes in Aqueous Solutions by VUV-Based AOPs

Table 2

The summary of the pseudo-first-order decomposition rate constant, 𝑘 (min⁻¹), of Acid Orange 8 by direct photolysis and the VUV/H₂O₂ process.

		Direct photolysis		Indirect oxidation
pH	𝑘VUV/H2O2	𝑘VUVonly	Contribution (%)	𝑘OH^⋅	Contribution	𝑘VUV/H2O2/𝑘VUVonly (%)
3	0.0474	0.0108	22.78	0.0366	77.22	4.39
5	0.0377	0.0106	28.12	0.0271	71.88	3.56
7	0.0430	0.0135	31.40	0.0295	68.60	3.19
9	0.0331	0.0119	35.95	0.0212	64.05	2.78
11	0.0213	0.0146	68.55	0.0067	31.45	1.46