ZnO-Assisted Photocatalytic Degradation of Congo Red and Benzopurpurine 4B in Aqueous Solution

Elaziouti,; Nadjia, Laouedj; Bekka, Ahmed

doi:10.4172/2157-7048.1000106

Cited by 24 publications

(22 citation statements)

References 17 publications

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“…As shown in non‐buffer initial pHs, decolorization at acidic pHs of 5 is comparable with pH of 7. This may be attributed to higher generation of hydrogen peroxide at acidic pH with respect to neutral pHs as reported in literature .…”

Section: Resultssupporting

confidence: 60%

“…This result can be explained based on the higher concentration of hydroxyl radicals in this basic pH with respect to other pHs. Another explanation can be presented so that, at initial pH of 11, ZnO surface has negative charge and hence the dye may be more adsorbed on it via hydrogen bonding in compared to dye adsorption at initial pHs of 2, 5, 7, or pH of 9 that lead to more photocatalytic decolorization of it . As shown in non‐buffer initial pHs, decolorization at acidic pHs of 5 is comparable with pH of 7.…”

Section: Resultsmentioning

confidence: 99%

“…The photoelectrons can participate in the reduction of dissolved oxygen, leading to formation of superoxide anion (

{normalO}_{2}^{-}

), hydroperoxide (HO 2 ) radicals, and hydrogen peroxide (H 2 O 2 (ads.)) while the photoproduced holes can oxidize directly the target molecules or indirectly by photogenerated radicals such as hydroxyl and hydroperoxide on the zinc oxide surface leading to degradation of dye molecules . The proposed stepwise photocatalytic pathway is shown in below:

ZnO + h ν \to ZnO true[{normale}^{-} true(CB true) + {normalh}^{+} true(VB true) true]

{normalO}_{2} + {normale}^{-} \to {normalO}_{2}^{• -}

{normalO}_{2}^{• -} + {normalH}^{+} \to^{•} {HO}_{2}

{normalO}_{2}^{• -} + {2 H}^{+} + {normale}^{-} \to {normalH}_{2} {normalO}_{2}

Dye + {normalh}^{+} \to {Dye}^{•}^{+}

{HO}^{-} + {normalh}^{+} \to^{•} OH

{normalH}_{2} O + {normalh}^{+} \to • OH + {normalH}^{+}

Dye +^{•} OH /^{•} {HO}_{2} \to {Dye}^{•}^{+}

…”

Section: Resultsmentioning

confidence: 99%

“…This is in agreement with pH effect on decolorization percentage as reported in many literature reports . The main oxidizing agents for decolorization of dye by UV‐light in the presence of photocatalysts are·OH, OOH radicals, and H 2 O 2 molecules . These species, along with others, are expected to be produced by UV‐light irradiation of the ZnO suspension.…”

Section: Resultsmentioning

confidence: 99%

“…The modified LH kinetic model was applied for evaluation of some kinetic data of the reaction occurring at a solid‐liquid interface. The LH equation can be expressed by Eq. :

1 / R = 1 / k_{normalr} K_{normalA} [C_{0}] + 1 / k_{normalr}

…”

Section: Resultsmentioning

confidence: 99%

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Catalytic thionine photodecolorization kinetics in the presence of nanostructure zinc oxide at buffer and non‐buffer solutions

Montazerozohori

Malekhoseini

2014

Env Prog and Sustain Energy

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Photocatalytic decolorization of thionine using nanostructure zinc oxide suspensions in various buffer and non‐buffer pHs under 400 W high pressure mercury lamp irradiation under aerobic condition has been performed. Some parameters such as, amount of nanophotocatalyst, irradiation time, buffer and non‐buffer initial pHs effect and initial concentration of dye in photoreactor cell have been investigated to obtain the optimum conditions at each buffer and non‐buffer initial pHs. Kinetic study suggested pseudo‐first‐order behavior for photodecolorization of dye at all considered pHs. The plots based on resultant data also showed that the photocatalytic processes obey from Langmuir‐Hinshelwood kinetic model. Ultimately, the observed rate constants (kobs) in the range of 1.20 × 10−2 − 1.15 × 10−1 and 1.46 × 10−2 − 7.69 × 10−2 min−1, photodecolorization rate constants (kr) in the range of 1.39–26.12 and 1.04–149.25 mg min−1 L−1, and adsorption constants (KA) in the range of 3.60 × 10−3 − 7.39 × 10−3 and 6.16 × 10−4 − 2.43 × 10−2 L. mg−1 were evaluated for non‐buffer and buffer media, respectively. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 689–696, 2015

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Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 99%

“…The photoelectrons can participate in the reduction of dissolved oxygen, leading to formation of superoxide anion (

{normalO}_{2}^{-}

ZnO + h ν \to ZnO true[{normale}^{-} true(CB true) + {normalh}^{+} true(VB true) true]

{normalO}_{2} + {normale}^{-} \to {normalO}_{2}^{• -}

{normalO}_{2}^{• -} + {normalH}^{+} \to^{•} {HO}_{2}

{normalO}_{2}^{• -} + {2 H}^{+} + {normale}^{-} \to {normalH}_{2} {normalO}_{2}

Dye + {normalh}^{+} \to {Dye}^{•}^{+}

{HO}^{-} + {normalh}^{+} \to^{•} OH

{normalH}_{2} O + {normalh}^{+} \to • OH + {normalH}^{+}

Dye +^{•} OH /^{•} {HO}_{2} \to {Dye}^{•}^{+}

…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The modified LH kinetic model was applied for evaluation of some kinetic data of the reaction occurring at a solid‐liquid interface. The LH equation can be expressed by Eq. :

1 / R = 1 / k_{normalr} K_{normalA} [C_{0}] + 1 / k_{normalr}

…”

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Catalytic thionine photodecolorization kinetics in the presence of nanostructure zinc oxide at buffer and non‐buffer solutions

Montazerozohori

Malekhoseini

2014

Env Prog and Sustain Energy

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A review on ultrasound assisted synthesis of metal oxide and doped metal oxide nanocatalysts and subsequent application as photocatalyst for dye degradation

Dey

Gogate

Gote

2023

Environmental Quality Mgmt

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In recent years, research on improving the synthesis of catalysts has been at the forefront because of advancements in nanotechnology and greener conventions. Using ultrasound (US) during nanocatalysts synthesis is one of the green approaches that can yield improved catalyst characteristics under conditions of shorter reaction time and requirement of low temperature and pressure. The current paper aims at giving an insight into US‐assisted synthesis (emphasized on sol‐gel and hydrothermal) of different metal oxide nanocatalysts. It has been elucidated that US‐assisted synthesis gives nanocatalyst with narrower particle size distribution with lower mean size, higher surface area, better morphology with less agglomeration, and higher catalytic activity. Ultrasound has thus been demonstrated to yield improvements in morphological, optical, and electronic properties of the nanocatalysts, however, scalability and industrial application of sonochemical synthesis have not been seen very popular. Some guidelines for future research into the development of novel nanocatalysts and industrial scale‐up studies are also provided. The review also summarizes the application of these metal oxides as photocatalysts for dye degradation or effluent treatment containing dyes, highlighting the fundamentals of photocatalysis as well. A comparative study has been reported for catalysts obtained using the US‐assisted synthesis and conventional synthesis of the photocatalysts in terms of catalytic activity. The benefits of using ultrasound‐assisted synthesis in terms of higher photocatalytic degradation have been clearly demonstrated.

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Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review

Raval

Shah

2016

Environ Sci Pollut Res

157

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Increasing amount of dyes in an ecosystem has propelled the search of various methods for dye removal. Amongst all the methods, adsorption occupies a prominent place in dye removal. Keeping this in mind, many adsorbents used for the removal of hazardous anionic azo dye Congo red (CR) from aqueous medium were reviewed by the authors. The main objectives behind this review article are to assemble the information on scattered adsorbents and enlighten the wide range of potentially effective adsorbents for CR removal. Thus, CR sorption by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites are surveyed and critically reviewed as well as their sorption capacities are also compared. This review also explores the grey areas of the adsorption performance of various adsorbents with reference to the effects of pH, contact time, initial dye concentration and adsorbent dosage. The equilibrium adsorption isotherm, kinetic and thermodynamic data of different adsorbents used for CR removal were also analysed. It is evident from a literature survey of more than 290 published papers that nanoparticle and nanocomposite adsorbents have demonstrated outstanding adsorption capabilities for CR. Graphical abstract ᅟ.

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ZnO-Assisted Photocatalytic Degradation of Congo Red and Benzopurpurine 4B in Aqueous Solution

Cited by 24 publications

References 17 publications

Catalytic thionine photodecolorization kinetics in the presence of nanostructure zinc oxide at buffer and non‐buffer solutions

Catalytic thionine photodecolorization kinetics in the presence of nanostructure zinc oxide at buffer and non‐buffer solutions

A review on ultrasound assisted synthesis of metal oxide and doped metal oxide nanocatalysts and subsequent application as photocatalyst for dye degradation

Adsorptive amputation of hazardous azo dye Congo red from wastewater: a critical review

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