Mineralization of Azo Dye Using Combined Photo-Fenton and Photocatalytic Processes under Visible Light

Table 1

Pseudo first-order rate constant values and extent of mineralization obtained in photocatalysis, photo-Fenton-like reactions, and combined systems (TiO₂ or N-TiO₂-Fe³⁺-oxidant and TiO₂ or N-TiO₂-Cu²⁺-oxidant).

Catalyst	Photodegradation rate constant; 𝑘1×10^4 (s^−1)	Extent of mineralization after 4 h (%)
TiO2	2.54	36
N-TiO2	5.85	51
TiO2 + PMS	23.7	75
N-TiO2 + PMS	27.1	78
Fe^3+ + PMS	22.85	74
Cu^2+ + PMS	16.95	70
TiO2 + Fe^3+ + PMS	30.13	91
TiO2 + Cu^2+ + PMS	26.52	89
N-TiO2 + Fe^3+ + PMS	34.35	95
N-TiO2 + Cu^2+ + PMS	28.82	90
TiO2 + PDS	4.10	65
N-TiO2 + PDS	7.05	68
Fe^3+ + PDS	6.95	71
Cu^2+ + PDS	6.67	58
TiO2 + Fe^3+ + PDS	14.71	80
TiO2 + Cu^2+ + PDS	22.10	86
N-TiO2 + Fe^3+ + PDS	19.38	84
N-TiO2 + Cu^2+ + PDS	26.45	87
TiO2 + H2O2	5.70	63
N-TiO2 + H2O2	9.25	67
Fe^3+ + H2O2	11.1	72
Cu^2+ + H2O2	6.18	62
TiO2 + Fe^3+ + H2O2	21.45	77
TiO2 + Cu^2+ + H2O2	17.30	76
N-TiO2 + Fe^3+ + H2O2	23.06	86
N-TiO2 + Cu^2+ + H2O2	20.85	76

[TiO₂] = [N-TiO₂] = 1.428 g L⁻¹; [Fe³⁺] = [Cu²⁺] = 0.2 mM; [RR180] = 5×10⁻⁵ M; [Oxidants] = 2 mM.