Photostability and photocatalytic degradation of ionic liquids in water under solar light

Bedia, Jorge; Rodrı́guez, Juan J.; Moreno, Daniel; Palomar, José; Belver, Carolina

doi:10.1039/c8ra07867j

Cited by 20 publications

(15 citation statements)

References 54 publications

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“…Several works found in the literature on pyridinium‐ and imidazolium‐based ILs removal by photocatalytic oxidation under UV irradiation showed complete ILs degradation in most cases, observing a clear stability for smaller ILs . The increase in alkyl‐chain length of imidazolium‐based ILs improved the cation degradation rate, despite this the photocatalytic degradation of Bmpyr + cation was also faster than imidazolium ones with greater molar weight …”

Section: Resultsmentioning

confidence: 99%

“…The ILs (HmimCl and BmpyrCl) and all other chemicals were purchased from Sigma‐Aldrich (St Louis, MO, USA). The properties of the photocatalyst (Aeroxide® TiO 2 ‐P25 from Evonik‐Degussa, Frankfurt, Germany) are described in detail elsewhere …”

Section: Methodsmentioning

confidence: 99%

“…The properties of the photocatalyst (Aeroxide® TiO 2 -P25 from Evonik-Degussa, Frankfurt, Germany) are described in detail elsewhere. 31…”

Section: Chemicalsmentioning

confidence: 99%

“…Nevertheless, to the best of our knowledge, photocatalytic degradation and advanced biological treatments in SBRs have scarcely been used for IL removal. Solar photocatalysis may be an effective choice for the chemical degradation of ILs and partial mineralization of organic matter thanks to the low environmental impact of solar light as inducer of ‘electron–hole’ pairs …”

Section: Introductionmentioning

confidence: 99%

“…Solar photocatalysis may be an effective choice for the chemical degradation of ILs and partial mineralization of organic matter thanks to the low environmental impact of solar light as inducer of 'electron-hole' pairs. 20,31 The aim of this work was to assess the efficiency of a sequential process involving photocatalytic degradation and biological treatment for the removal of 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-butyl-4-methylpyridinium chloride (BmpyrCl) from aqueous solution. An optimal catalyst and ILs concentration were used in the chemical oxidation step to obtain biodegradable and scarcely ecotoxic effluents for subsequent biodegradation in an SBR with increased organic matter conversion in terms of COD removal and TOC mineralization.…”

Section: Introductionmentioning

confidence: 99%

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Ionic liquids removal by sequential photocatalytic and biological oxidation

Gomez‐Herrero

Tobajas

Rodríguez

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUND The industrial application of ionic liquids (ILs) can induce the generation of wastewater and their release into the aquatic media. ILs can be efficiently removed by advanced oxidation processes (AOPs), which are expensive to implement. An alternative, using solar photocatalysis and biological degradation in combination, was used here to remove 1‐hexyl‐3‐methylimidazolium chloride (HmimCl) and 1‐butyl‐4‐methylpyridinium chloride (BmpyrCl). The chemical pretreatment allowed the ILs to be converted into by‐products for easier biodegradation in a sequential batch reactor (SBR). RESULTS Photocatalytic degradation, using 0.25 g TiO2 L−1 and 600 W m−2 solar radiation for 24 h, allowed a complete ILs removal and a partial mineralization of the organic matter, 28% for Bmpyr+ and 35% for Hmim+. A degradation pathway based on the by‐products identified was proposed for each IL. The reaction effluents were submitted to a biological treatment in an SBR, using organic loading rates of 0.18–0.2 kg COD kg−1 VSS d−1 and a biomass concentration of 3.5 g VSS L−1 in 8 h cycles. The combined treatment allowed highly efficient removal of organic matter [total organic carbon (TOC) conversion exceeded 75% for HmimCl and 78% for BmpyrCl]. CONCLUSION Solar photocatalytic oxidation efficiently removed ILs and produced more biodegradable and less ecotoxic effluents. Biological oxidation increased TOC and chemical oxygen demand (COD) removal to more than 75% for the overall treatment. Combining solar photocatalysis and biological degradation therefore provided an effective system for IL removal. © 2019 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The properties of the photocatalyst (Aeroxide® TiO 2 -P25 from Evonik-Degussa, Frankfurt, Germany) are described in detail elsewhere. 31…”

Section: Chemicalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ionic liquids removal by sequential photocatalytic and biological oxidation

Gomez‐Herrero

Tobajas

Rodríguez

et al. 2020

J of Chemical Tech & Biotech

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Understanding the Photoexcitation of Room Temperature Ionic Liquids

2020

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Photoexcitation of (neat) room temperature ionic liquids (RTILs) leads to the observation of transient species that are reminiscent of the composition of the RTILs themselves. In this minireview, we summarize state‐of‐the‐art in the understanding of the underlying elementary processes. By varying the anion or cation, one aim is to generally predict radiation‐induced chemistry and physics of RTILs. One major task is to address the fate of excess electrons (and holes) after photoexcitation, which implies an overview of various formation mechanisms considering structural and dynamical aspects. Therefore, transient studies on time scales from femtoseconds to microseconds can greatly help to elucidate the most relevant steps after photoexcitation. Sometimes, radiation may eventually result in destruction of the RTILs making photostability another important issue to be discussed. Finally, characteristic heterogeneities can be associated with specific physicochemical properties. Influencing these properties by adding conventional solvents, like water, can open a wide field of application, which is briefly summarized.

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