UV-LED/ilmenite/persulfate for azo dye mineralization: The role of sulfate in the catalyst deactivation

Silveira, Jefferson E.; Paz, Wendel S.; García‐Muñoz, Patricia; Zazo, Juan A.; Casas, José A.

doi:10.1016/j.apcatb.2017.07.072

Cited by 62 publications

(17 citation statements)

References 59 publications

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“…Surface-mediated oxidation can also be induced via the formation of NO 2 , which can partition to gas-phase during the time scale of the experiment . The OH radicals formed by reactions and have been shown to enhance the reduction of surface Fe 3+ to Fe 2+ , especially in particles containing large amounts of α-Fe 2 O 3 . ,,− However, as shown in Figure , no significant enhancement of Fe 2+ was observed during the photolysis experiments in HNO 3 because of the relatively low concentrations of α-Fe 2 O 3 in FA compared to that in mineral dust. In addition, the absence of dissolved oxygen and the relatively low concentrations of NO 2 – (aq) formed during the reaction time scale lead to relatively low concentrations of the OH radical, making its effect on iron mobility negligible compared to the acidic media and solar flux.…”

Section: Resultsmentioning

confidence: 99%

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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Atmospheric combustion particles, such as fly ash emitted from coal-fired power plants, are a potential source of atmospheric iron, with significant implications in climate and global biogeochemical cycles. While the iron content and speciation of fly ash depend closely on the source region and combustion process, few studies have been carried out comparing the atmospheric processing of fly ash produced from coal-fired power plants in different regions. In this study, we present an investigation of iron dissolution in acidic aqueous solutions: HNO 3 and HCl at pH 1 and pH 2 under daytime and nighttime conditions for three fly ash samples from three different sources: United States (USFA), Central Europe (EUFA), and India fly ash (INFA). Iron mobility and speciation depend on the source region and the combustion efficiency that generates fly ash. In HCl suspensions, proton-promoted mechanisms lead to larger fractions of aqueous-phase iron leached from fly ash particles, with poorly combusted samples providing significant fractions of Fe 2+ . In HNO 3 suspensions, a surface-mediated redox reaction suppresses the mobility of Fe 2+ , leading to the formation of nitrites. In the presence of solar radiation, previously unrecognized pathways of atmospheric processing enhance the formation Fe 2+ and nitrous acid from combustion particles. The information provided herein could be significant to increase our understanding of the effects of combustion particles in the atmospheric chemical balance regarding iron and nitrites.

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Section: Resultsmentioning

confidence: 99%

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Kim

Xiao

Karchere-Sun

et al. 2020

ACS Earth Space Chem.

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“…The dose of oxidant is an important parameter to be taken into account in the optimization of any AOP since it has a high contribution in the cost of the treatment process. For this purpose, five experiments were carried out, being the persulphate concentration varied in the range from 0.8 g/L to 8.0 g/L (corresponding to 0.1 and 1.0 times the stoichiometric amount of persulphate required for total elimination of the chemical oxygen demand (COD)-12 g persulphate /g COD [37]).…”

Section: Influence Of Persulphate Concentrationmentioning

confidence: 99%

UV/Vis-Based Persulphate Activation for p-Nitrophenol Degradation

et al. 2021

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In the present work, the degradation of p-nitrophenol (PNP) and its mineralization by a UV/Vis-based persulphate activation process was investigated. Firstly, a screening of processes as direct photolysis, persulphate alone and persulphate activated by radiation was performed. The incidence of radiation demonstrated to have an important role in the oxidant activation, allowing to achieve the highest PNP and total organic carbon (TOC) removals. The maximum PNP oxidation (100%) and mineralization (61.6%)—both after 2 h of reaction time—were reached when using T = 70 °C, (S2O82−) = 6.4 g/L and I = 500 W/m2. The influence of radiation type (ultraviolet/visible, visible or simulated solar light) was also evaluated, being found that the source with the highest emission of ultraviolet radiation (UV/visible) allowed to achieve the best oxidation efficiency; however, solar radiation also reached very-good performance. According to quenching experiments, the sulphate radical is key in the activated persulphate oxidation process, but the hydroxyl radical also plays an important role.

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“…UV-LEDs are physically small, mercury-free, and characterized by fast startup time and long lifespan compared to the traditional mercury vapor lamps [17]. LEDs also emit light at specific wavelengths, allowing for flexible tailoring of UV system designs that combine selected wavelengths to achieve optimal inactivation of various pathogens [18], and mineralization and degradation of persistent contaminants [19][20][21][22]. Being a new technology, UV-LEDs suffer from low power and energy efficiencies at the shorter wavelengths; however, these parameters are constantly being improved [23].…”

Section: Introductionmentioning

confidence: 99%

UV-LED Combined with Small Bioreactor Platform (SBP) for Degradation of 17α-Ethynylestradiol (EE2) at Very Short Hydraulic Retention Time

et al. 2021

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Degradation of 17α-ethynylestradiol (EE2) and estrogenicity were examined in a novel oxidative bioreactor (OBR) that combines small bioreactor platform (SBP) capsules and UV-LED (ultraviolet light emission diode) simultaneously, using enriched water and secondary effluent. Preliminary experiments examined three UV-LED wavelengths—267, 279, and 286 nm, with (indirect photolysis) and without (direct photolysis) H2O2. The major degradation wavelength for both direct and indirect photolysis was 279 nm, while the major removal gap for direct vs. indirect degradation was at 267 nm. Reduction of EE2 was observed together with reduction of estrogenicity and mineralization, indicating that the EE2 degradation products are not estrogens. Furthermore, slight mineralization occurred with direct photolysis and more significant mineralization with the indirect process. The physical–biological OBR process showed major improvement over other processes studied here, at a very short hydraulic retention time. The OBR can feasibly replace the advanced oxidation process of UV-LED radiation with catalyst in secondary sedimentation tanks with respect to reduction ratio, and with no residual H2O2. Further research into this OBR system is warranted, not only for EE2 degradation, but also to determine its capabilities for degrading mixtures of pharmaceuticals and pesticides, both of which have a significant impact on the environment and public health.

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UV-LED/ilmenite/persulfate for azo dye mineralization: The role of sulfate in the catalyst deactivation

Cited by 62 publications

References 59 publications

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

Atmospheric Processing of Anthropogenic Combustion Particles: Effects of Acid Media and Solar Flux on the Iron Mobility from Fly Ash

UV/Vis-Based Persulphate Activation for p-Nitrophenol Degradation

UV-LED Combined with Small Bioreactor Platform (SBP) for Degradation of 17α-Ethynylestradiol (EE2) at Very Short Hydraulic Retention Time

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