Kinetics of three commercial textile dyes decomposition by UV/H2O2 and UV/acetone processes: An experimental comparative study and DFT calculations
•Efficacy of three dyes degradation by UV/H2O2 and UV/acetone was investigated.•UV/acetone process, based on methyl radicals, was more efficient.•The removal rates were found to be pseudo-first order in all cases.•The removal order was as follows: RO4 > DR80 > RR184.•DFT calculations have been...
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| Published in: | Journal of molecular liquids Vol. 383; p. 122212 |
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| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-08-2023
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | •Efficacy of three dyes degradation by UV/H2O2 and UV/acetone was investigated.•UV/acetone process, based on methyl radicals, was more efficient.•The removal rates were found to be pseudo-first order in all cases.•The removal order was as follows: RO4 > DR80 > RR184.•DFT calculations have been performed to explain this order.
Acetone photolysis was investigated and compared with the UV/H2O2 process for the removal of three commercial textile dyes, Reactive Red 184 (RR184), Reactive Orange 4 (RO4), and Direct Red 80 (DR80), in aqueous solution at 254 nm, pH = 6.5–6.8, and T = 20 ± 2 °C. The removal efficiency of RR184, RO4, and DR80 by UV/H2O2 was 35 %, 59 %, and 69 %, respectively, whereas UV/acetone exhibited a removal efficiency of 81 %, 99 %, and 88 %, within 30 min ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). However, as the initial doses of H2O2 and acetone were increased, the decolorization increased, and the experimental kinetic data always agreed with the pseudo-first-order reaction model (R2 = 0.94–0.99). Additionally, UV/acetone was consistently shown to be significantly more efficient than UV/H2O2 under all conditions tested. For instance, the rate constant ratios kUV/acetone/kUV/H2O2 are 3.19, 1.95, and 1.67 for RR184, RO4, and DR80, respectively ([Dye]0 = 0.1 mM and [acetone]0 = [H2O2]0 = 50 mM). Scavenging tests using specific probes revealed that •OH and •CH3 radicals were the main responsible for dyes degradation (greater than80 %) in the UV/H2O2 and UV/acetone processes, respectively. In both systems, the dyes' reactivity order was found to be RO4 > DR80 > RR184, indicating that chemical structure is an important factor in evaluating the efficiency of the degradation process. This reactivity order was supported by the density functional theory (DFT)-based thermodynamic calculations used to explain the HO•-initiated degradation of the studied azo dyes in the UV/H2O2 process. |
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| ISSN: | 0167-7322 1873-3166 |
| DOI: | 10.1016/j.molliq.2023.122212 |