Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater
We have explored the simultaneous degradation of cyanides and thiocyanate present in wastewaters from a cokemaking factory using photoassisted methods under varied illumination conditions (from simulated solar light to UV light). Overall, the photochemical degradation of cyanides was more efficient...
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doaj-21909477c4dd4957a6fba20406e71a6a2020-11-25T00:58:53ZengMDPI AGMolecules1420-30492019-04-01247137310.3390/molecules24071373molecules24071373Photochemical Degradation of Cyanides and Thiocyanates from an Industrial WastewaterJuan Jose Viña Mediavilla0Begoña Fernandez Perez1Maria C. Fernandez de Cordoba2Julia Ayala Espina3Conchi O. Ania4Escuela Técnica Superior de Ingeniería de Minas, Universidad de Oviedo, 33001 Oviedo, SpainEscuela Técnica Superior de Ingeniería de Minas, Universidad de Oviedo, 33001 Oviedo, SpainCEMHTI, CNRS (UPR 3079), Université d’Orléans, 45071 Orléans, FranceEscuela Técnica Superior de Ingeniería de Minas, Universidad de Oviedo, 33001 Oviedo, SpainCEMHTI, CNRS (UPR 3079), Université d’Orléans, 45071 Orléans, FranceWe have explored the simultaneous degradation of cyanides and thiocyanate present in wastewaters from a cokemaking factory using photoassisted methods under varied illumination conditions (from simulated solar light to UV light). Overall, the photochemical degradation of cyanides was more efficient than that of thiocyanates, regardless of the illumination conditions, the effect being more pronounced in the absence of a photocatalyst. This is due to their different degradation mechanism that in the case of thiocyanates is dominated by fast recombination reactions and/or charge transfer reactions to electron scavengers. In all cases, cyanate, ammonia, nitrates, and nitrites were formed at different amounts depending on the illumination conditions. The conversion yield under simulated solar light was almost complete for cyanides and quite high for thiocyanates after 6 h of illumination. Regarding toxicity, photochemical oxidation at 254 nm and under simulated solar light decreased significantly the toxicity of the pristine wastewater, showing a correlation with the intensity of the irradiation source. This indicate that simulated light can be effectively used to reduce the toxicity of industrial effluents, opening an interesting perspective for optimizing cyanide detoxification systems based on natural light.https://www.mdpi.com/1420-3049/24/7/1373cyanidesthiocyanatesoxidationphotooxidationsolar light |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Juan Jose Viña Mediavilla Begoña Fernandez Perez Maria C. Fernandez de Cordoba Julia Ayala Espina Conchi O. Ania |
spellingShingle |
Juan Jose Viña Mediavilla Begoña Fernandez Perez Maria C. Fernandez de Cordoba Julia Ayala Espina Conchi O. Ania Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater Molecules cyanides thiocyanates oxidation photooxidation solar light |
author_facet |
Juan Jose Viña Mediavilla Begoña Fernandez Perez Maria C. Fernandez de Cordoba Julia Ayala Espina Conchi O. Ania |
author_sort |
Juan Jose Viña Mediavilla |
title |
Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater |
title_short |
Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater |
title_full |
Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater |
title_fullStr |
Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater |
title_full_unstemmed |
Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater |
title_sort |
photochemical degradation of cyanides and thiocyanates from an industrial wastewater |
publisher |
MDPI AG |
series |
Molecules |
issn |
1420-3049 |
publishDate |
2019-04-01 |
description |
We have explored the simultaneous degradation of cyanides and thiocyanate present in wastewaters from a cokemaking factory using photoassisted methods under varied illumination conditions (from simulated solar light to UV light). Overall, the photochemical degradation of cyanides was more efficient than that of thiocyanates, regardless of the illumination conditions, the effect being more pronounced in the absence of a photocatalyst. This is due to their different degradation mechanism that in the case of thiocyanates is dominated by fast recombination reactions and/or charge transfer reactions to electron scavengers. In all cases, cyanate, ammonia, nitrates, and nitrites were formed at different amounts depending on the illumination conditions. The conversion yield under simulated solar light was almost complete for cyanides and quite high for thiocyanates after 6 h of illumination. Regarding toxicity, photochemical oxidation at 254 nm and under simulated solar light decreased significantly the toxicity of the pristine wastewater, showing a correlation with the intensity of the irradiation source. This indicate that simulated light can be effectively used to reduce the toxicity of industrial effluents, opening an interesting perspective for optimizing cyanide detoxification systems based on natural light. |
topic |
cyanides thiocyanates oxidation photooxidation solar light |
url |
https://www.mdpi.com/1420-3049/24/7/1373 |
work_keys_str_mv |
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