Innovative Supported Composite Photocatalyst for the Oxidation of Phenolic Waters in Reactor Processes

Raja, P.; Bandara, Jayasundera; Giordano, P.; Kiwi, J.

doi:10.1021/ie050689m

Cited by 10 publications

(9 citation statements)

References 17 publications

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“…This support was selected since: (a) it resists the attack of the highly oxidative radicals generated by the oxone decomposition catalyzed by Mn 2+ or Cu 2+ [10,11], (b) it also resists he decomposition of oxone recently reported by Co 2+ -ions [12,13] and (c) provides a large surface area in the reactor to induce accelerated Orange II decomposition. The short photodiscoloration times attained in the minute range are impressive compared with times needed by the TiO 2 /RR photocatalyst to degrade organic compounds under similar experimental conditions irradiation [7][8][9]. The experimental evidence for the accelerated kinetic performance observed is provided by XPS spectroscopy by identifying unambiguously the strong oxidation properties of the Co 3 O 4 .…”

Section: Introductionmentioning

confidence: 84%

“…Thus, the catalyst immobilization is a necessary step to avoid the costly end-of-pipe separation step [6]. In our laboratory, the immobilization of TiO 2 on Raschig rings (RR) has been recently the subject of some recent studies concerning the degradation pollutants under light irradiation [7][8][9]. As a natural continuation of these studies, the present work addresses the fixation of Co 3 O 4 on Raschig rings to produce a catalyst that would accelerate oxone decomposition.…”

Section: Introductionmentioning

confidence: 98%

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Accelerated photodegradation (minute range) of the commercial azo-dye Orange II mediated by Co3O4/Raschig rings in the presence of oxone

Zhang

Bensimon²,

Laub³

et al. 2007

Journal of Molecular Catalysis A: Chemical

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The accelerated discoloration of Orange II by an innovative Co 3 O 4 /Raschig ring photocatalyst (from now on Co 3 O 4 /RR) is feasible and proceeds to completion using oxone as an oxidant within the surprisingly short time of ∼5 min. The preparation of Co 3 O 4 small clusters (2-10 nm in size) on RR is reported. The discoloration/mineralization of the azo-dye Orange II was carried out in a concentric coaxial photo-reactor and was a function of the Orange II and oxone concentrations, the solution pH and the recirculation rate. At bio-compatible pH-values, the concentration of Co-ions in solution after photocatalysis (15 min) was found to be between 0.5 and 2 ppm, within the limits allowed for treated waters. The generation of peroxide was observed as long as Orange II was still available in solution.By elemental analysis (EA), the amount of Co of the Raschig rings was determined to be ∼65% (w/w) before and after the photocatalysis. This confirms the stability observed during long-term operation of the Co 3 O 4 /RR catalyst. The sizes of the Co 3 O 4 clusters on the RR surface were determined by transmission electron spectroscopy (TEM). A non-uniform distribution of Co 3 O 4 particles on RR with sizes between 2 and 10 nm was found. The presence of Co-clusters on the RR-surface was confirmed by electron dispersive spectroscopy (EDS) showing 12.6% surface Co-enrichment before the photocatalysis and 18.8% surface enrichment after the photocatalysis. By confocal microscopy the irregularly thick shaped Co 3 O 4 on the Raschig rings was analyzed. The most striking observation is very large shift of Co2p3/2 line from 779.6 eV at time zero to 782.2 eV within 10 min after due to the photocatalysis taking place. This indicates a strong reduction of electron density on the cobalt atoms of Co 3 O 4 /RR and providing the evidence for the strong oxidation properties of this catalyst.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 98%

Accelerated photodegradation (minute range) of the commercial azo-dye Orange II mediated by Co3O4/Raschig rings in the presence of oxone

Zhang

Bensimon²,

Laub³

et al. 2007

Journal of Molecular Catalysis A: Chemical

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“…Photocatalytic materials have gained extraordinary relevance in the last years due to their potential applications in fields such as photo-induced removal of pollutants from air and water, and self-cleaning and antibacterial materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Titanium dioxide (TiO 2 ) is the most widely investigated photocatalyst due to its high photoactivity, low cost, low toxicity and good chemical and thermal stability [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, most photocatalytic coatings are prepared by the post-deposition of the catalyst onto a substrate, such as, glass, textiles, metals or polymers [2,[5][6][7][8][9]12]. In the case of photocatalytic waterborne paints, the photocatalyst (TiO 2 ) usually is one of the components of the paint formulation that is blended with the waterborne dispersed polymer (binder) [3,10,11,15].…”

Section: Introductionmentioning

confidence: 99%

Photoactive self-cleaning polymer coatings by TiO2 nanoparticle Pickering miniemulsion polymerization

González

Bonnefond

Barrado

et al. 2015

Chemical Engineering Journal

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“…This approach has also been used to degrade several aromatic compounds in aqueous solution [8][9][10]. Our laboratory has reported Raschig rings coated by TiO 2 as a catalyst to degrade phenol-compounds [11], phenol [12] and chlorophenols [13]. This study addresses the preparation of Raschig rings coated with TiO 2 but adding small amounts of a 3d-transition element like Cu/Cu-ions to extend its absorption into the visible region with the objective of increasing the dye degradation kinetics under solar light.…”

Section: Introductionmentioning

confidence: 99%

Cu-decorated Raschig-TiO 2 rings inducing MB repetitive discoloration without release of Cu-ions under solar light

Suárez

Zhang

Teixidó

et al. 2017

Journal of Environmental Chemical Engineering

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A B S T R A C TThe methylene blue (MB) discoloration on innovative photocatalysts made up of Raschig-rings coated by pre-formed TiO 2 nanoparticles decorated with CuOx (RR@TiO 2 -Cu) is presented. The MB-discoloration was drastically accelerated by the subsequent addition of 0.004% Cu. This Cu-content being $3000 times below the TiO 2 present in the RR@TiO 2 samples led to MB-discoloration in shorter times. The Cu-ions released from the RR@TiO 2 -Cu 0.004% were determined 1ppb by inductively coupled plasma massspectrometry (ICP-MS). Cu-percentages >0.018% decreased the MB-discoloration kinetics due to the Cu acting as recombination sites for the photogenerated charges. The total organic carbon (TOC) reduction concomitant with the MB-discoloration is reported as well as the effect of the initial MB-concentration and pH on the discoloration kinetics. The Cu-addition shifted significantly the TiO 2 absorption into the visible region even when added in sub-microgram quantities (0.004%) to RR@TiO 2 as detected by diffuse reflectance spectroscopy (DRS). The Cu level added to RR@TiO 2 was too low to be detected by X-ray diffraction (XRD). The roughness of the RR@TiO 2 -Cu (0.018%-0.081% Cu) presented Rg-values between 11.8 nm and 23.9 nm. The RR@TiO 2 Cu presented agglomerate sizes of $200 nm for TiO 2 and for the Cu aggregates sizes of $20 nm. The MB discoloration kinetics and reuse of the RR@TiO 2 -Cu suggest the potential as a supported catalyst in environmental cleaning process. A reaction mechanism is suggested taking into consideration the role of the Cu 1+/2+ intra-gap states involving redox catalysis as detected by X-ray photoelectron-spectroscopy (XPS).

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Innovative Supported Composite Photocatalyst for the Oxidation of Phenolic Waters in Reactor Processes

Cited by 10 publications

References 17 publications

Accelerated photodegradation (minute range) of the commercial azo-dye Orange II mediated by Co3O4/Raschig rings in the presence of oxone

Accelerated photodegradation (minute range) of the commercial azo-dye Orange II mediated by Co3O4/Raschig rings in the presence of oxone

Photoactive self-cleaning polymer coatings by TiO2 nanoparticle Pickering miniemulsion polymerization

Cu-decorated Raschig-TiO 2 rings inducing MB repetitive discoloration without release of Cu-ions under solar light

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