Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight

Idris, Ani; Hassan, Nursia; Rashid, Roslina; Ngomsik, Audrey Flore

doi:10.1016/j.jhazmat.2010.11.101

Cited by 157 publications

(77 citation statements)

References 20 publications

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“…Consequently, the incorporation of maghemite into various photocatalyst matrices has been explored to fabricate magnetically separable composite photocatalysts for easy recovery and recycling [104,105]. Interestingly, despite the sensitivity to an external magnetic field, when the magnetic field is removed, the γ-Fe 2 O 3 -incorporating nanocomposites do not retain any significant residual magnetism that would otherwise cause problems by creating large clusters of magnetised particles during water treatment [106].…”

Section: Maghemite (γ-Fe 2 O 3 )-Based Magnetic Photocatalystsmentioning

confidence: 99%

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Mamba

Mishra

2016

Catalysts

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Organic and inorganic compounds utilised at different stages of various industrial processes are lost into effluent water and eventually find their way into fresh water sources where they cause devastating effects on the ecosystem due to their stability, toxicity, and non-biodegradable nature. Semiconductor photocatalysis has been highlighted as a promising technology for the treatment of water laden with organic, inorganic, and microbial pollutants. However, these semiconductor photocatalysts are applied in powdered form, which makes separation and recycling after treatment extremely difficult. This not only leads to loss of the photocatalyst but also to secondary pollution by the photocatalyst particles. The introduction of various magnetic nanoparticles such as magnetite, maghemite, ferrites, etc. into the photocatalyst matrix has recently become an area of intense research because it allows for the easy separation of the photocatalyst from the treated water using an external magnetic field. Herein, we discuss the recent developments in terms of synthesis and photocatalytic properties of magnetically separable nanocomposites towards water treatment. The influence of the magnetic nanoparticles in the optical properties, charge transfer mechanism, and overall photocatalytic activity is deliberated based on selected results. We conclude the review by providing summary remarks on the successes of magnetic photocatalysts and present some of the future challenges regarding the exploitation of these materials in water treatment.

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Section: Maghemite (γ-Fe 2 O 3 )-Based Magnetic Photocatalystsmentioning

confidence: 99%

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Mamba

Mishra

2016

Catalysts

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“…During irradiation, 5 mL aliquots were taken at a scheduled interval and centrifuged immediately to remove the particle. The residual concentration of Cr(VI) in the supernatant solution was measured by a 1,5-diphenylcarbazide spectrophotometric method with a spectrophotometer at 540 nm wavelength [26,27]. The concentration of RhB and 4-NP aqueous solution was analyzed at maximum absorption of 554 nm and 317 nm, respectively.…”

Section: Photocatalytic Experimentsmentioning

confidence: 99%

Controllable Synthesis of Zn₂GeO₄Nanorods for Photocatalytic Reduction of Aqueous Cr(VI) and Oxidation of Organic Pollutants

Liu

Jin

Shi

et al. 2015

Journal of Nanotechnology

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Zn 2 GeO 4 nanorods were successfully synthesized by a simple hydrothermal method. The composition, morphology, and optical properties of as-synthesized Zn 2 GeO 4 samples were characterized by X-ray diffraction, scan electron microscopy, and UV-vis diffuse reflectance spectra. The photocatalytic properties of Zn 2 GeO 4 nanorods were evaluated by the reduction of Cr(VI) and oxidation of organic pollutants in aqueous solution. The effects of solution pH on Cr(VI) reduction by Zn 2 GeO 4 nanorods were studied in detail. The results indicated that the efficiency of Cr(VI) reduction was highest at pH 5.96. Moreover, Zn 2 GeO 4 nanorods also showed excellent photocatalytic ability for the oxidation of organic pollutants such as rhodamine B and 4-nitrophenol.

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“…In general, the studies covered many aspects of photocatalysis includ-ing the influence of the (a) type of photocatalyst [4,5,6,7], (b) irradiation intensity [8], (c) photocatalyst loading [9], (d) Cr(VI) pollutant concentration [9], (e) solution pH [10], and (f) addition of radical scavengers [11] on the rate of reduction of Cr(VI) to Cr(III) with the objective of optimizing the process. The findings indicate that (a) the rate of reduction increases but photoefficiency decreases with increasing irradiance, (b) the percentage of Cr(VI) photoreduced increases to a maximum and then decrease with increasing photocatalyst loading, (c) the rate of reduction increases but percentage of Cr(VI) reduced decreases with increasing Cr(VI) concentration, and (d) the rate of reduction decreases with increasing pH.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Reduction of Aqueous Cr(VI) with CdS under Visible Light Irradiation: Effect of Particle Size

Makama

Salmiaton

Saion

et al. 2016

Bull. Chem. React. Eng. Catal.

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Stringent environmental standards have made the removal of Cr(VI) from water an important problem for environmental scientist and engineering. Heterogeneous photocatalysis using suspended photocatalyst is an interesting technique to consider for this application. In this work, the influence of particle size of suspended CdS on the photocatalytic reduction of aqueous Cr(VI) ion was investigated. The efficiency of Cr(VI) reduction was monitored through UV-visible analysis. The experimental results showed that the nanoparticle size has a dramatic effect on the adsorption and reduction of Cr(VI). As surface area increased from 44.2±0.6 to 98.7±0.5 m 2 /g due to particle size reduction, the rate of Cr(VI) reduction nearly doubled in the first 20 min of visible light irradiation. The results evidenced the inverse relationship between the apparent reduction rate constant and the CdS particle size. Conversely, the half-life (t1/2) period of the photocatalytic reduction has a direct relationship with CdS particle sizes.

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Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight

Cited by 157 publications

References 20 publications

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Controllable Synthesis of Zn₂GeO₄Nanorods for Photocatalytic Reduction of Aqueous Cr(VI) and Oxidation of Organic Pollutants

Photocatalytic Reduction of Aqueous Cr(VI) with CdS under Visible Light Irradiation: Effect of Particle Size

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Kinetic and regeneration studies of photocatalytic magnetic separable beads for chromium (VI) reduction under sunlight

Cited by 157 publications

References 20 publications

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

Controllable Synthesis of Zn2GeO4Nanorods for Photocatalytic Reduction of Aqueous Cr(VI) and Oxidation of Organic Pollutants

Photocatalytic Reduction of Aqueous Cr(VI) with CdS under Visible Light Irradiation: Effect of Particle Size

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Controllable Synthesis of Zn₂GeO₄Nanorods for Photocatalytic Reduction of Aqueous Cr(VI) and Oxidation of Organic Pollutants