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Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst./
Author:	Zwane, Qedile Innocent.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	162 p.
Notes:	Source: Masters Abstracts International, Volume: 82-11.
Contained By:	Masters Abstracts International82-11.
Subject:	Aqueous solutions. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28280586
ISBN:	9798708761903

Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst.
Zwane, Qedile Innocent.

Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 162 p.

Source: Masters Abstracts International, Volume: 82-11.

Thesis (M.Sc.)--University of Johannesburg (South Africa), 2019.

This item must not be sold to any third party vendors.

Sustainable development goals emphasise the importance of access to clean drinking water. However, due to industrialisation, a lot of pollutants find their way into water bodies. Heavy metals like chromium and arsenic are some of the most dangerous pollutants that are accumulating in water bodies due to anthropogenic processes. Recent research reported precipitation, coagulation, membrane technology, adsorption and flocculation as some of the possible techniques for the removal of these pollutants. However, all these techniques have serious draw back including that they produce sludge that may require further treatment or have high operational costs which make the impractical to use in real life. The purification of water through photocatalysis using nanoparticles (NPs) has emerged as one of the most promising approach to solving the issue of wastewater treatment. This work presents the use of novel multiphase BiVO4 NPs for the removal of hexavalent chromium from wastewater.Novel Y3+ and Mo6+ dual-doped, multiphase BiVO4 NPs were synthesized using a modified hydrothermal method through a gradient doping method. Yttrium (III) was used as a phase-stabilizing agent for the tetragonal phase while Mo6+ was used to control the volume of the crystals. The NPs were characterized using scan electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transform Infrared spectroscopy (FTIR), X-Ray diffraction spectroscopy (XRD) and Braunnauer-Emmett -Teller theory (BET) to determine crystal phase, morphology and surface area. It was found that introduction of the dopants and formation of the phase junction lead to a diminished PL spectra indicative of reduced electron-hole recombination. The 10% (m-m) Y-Mo dual-doped multiphase BiVO4 NPs showed the highest electron-hole separation efficiency. However, 15% (m-m) Y-Mo had the least charge separation and due to the formation of recombination centers at high degree s of metal doping. The multiphase systems also showed a red shift in the UV-Vis absorption spectrum. The Mott-Schottky plot obtained from Electro Impedance Spectroscopy confirmed formation of a phase junction in the multiphase systems which resulted in an improvement of the photocurrent to twice that of the pristine BiVO4 NPs for the 10% Y-Mo BiVO4 NPs.The photocurrent for 10% Y-Mo was 0.025 A.cm-2 while that of the pristine BiVO4 NPs was about 0.014 A.cm-2. This increase in photocurrent proves the improvement of charge separation. BET results showed that surface area increased with an increase in the degree of doping and that the 10% Y-Mo dual doped BiVO4 nanomaterials had a surface area of 9.009 m2/g.These NPs were then employed in the photoreduction of Cr6+ in synthetic wastewater first to study the effect of pH, loading of photocatalyst, loading of Cr6+ and temperature. The optimum conditions were then applied for photoreduction in real wastewater samples to study the effect of the water matrix. A photoreactor was used for photoreduction of Cr6+ to Cr3+ and the change in concentration of the Cr6+ was measured using with UV-Vis photometric techniques. It was found that the 10% Y-Mo multiphase BiVO4 had the highest photoreduction efficiency for the Cr6+ of 99.1% in 60 minutes. The reduction efficiency was also found to increase with decrease in pH, initial concentration of Cr6+ and temperature. There was an increase in the photoreduction efficiency with increase in loading of photocatalyst up to a 2g beyond which increase in photocatalyst loading leads to a diminished photoreduction efficiency due to the promotion of aggregation of the Nanoparticles (NPs). The optimum condition for the experiment were set at 10ppm of Cr6+, 25 °C , 1g of photocatalyst and pH of 1. It was also found that the photoreduction of Cr6+ in real wastewater was more efficient reaching 100% in 50 minutes and this was attributed to the presence of hole scavenging species in the wastewater. These results showed that the project was a success. It was recommended that in following studies the multiphase BiVO4 NPs be tested for the photodegradation of organic pollutants. It was also recommended that a comprehensive nanotoxicology study should be undertaken for the multiphase BiVO4 NPs to determine their effect on the environment and on living organisms.

ISBN: 9798708761903Subjects--Topical Terms:

3681511
Aqueous solutions.
Subjects--Index Terms:

Photoreduction

Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst.
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245 1 0 $a Photoreduction of Chromium (VI) Using Multi-Phase Bismuth Vanadate (BiVO4) Photocatalyst.
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300 $a 162 p.
500 $a Source: Masters Abstracts International, Volume: 82-11.
500 $a Advisor: Dlamini, L. N. ;Moeno, S.
502 $a Thesis (M.Sc.)--University of Johannesburg (South Africa), 2019.
506 $a This item must not be sold to any third party vendors.
520 $a Sustainable development goals emphasise the importance of access to clean drinking water. However, due to industrialisation, a lot of pollutants find their way into water bodies. Heavy metals like chromium and arsenic are some of the most dangerous pollutants that are accumulating in water bodies due to anthropogenic processes. Recent research reported precipitation, coagulation, membrane technology, adsorption and flocculation as some of the possible techniques for the removal of these pollutants. However, all these techniques have serious draw back including that they produce sludge that may require further treatment or have high operational costs which make the impractical to use in real life. The purification of water through photocatalysis using nanoparticles (NPs) has emerged as one of the most promising approach to solving the issue of wastewater treatment. This work presents the use of novel multiphase BiVO4 NPs for the removal of hexavalent chromium from wastewater.Novel Y3+ and Mo6+ dual-doped, multiphase BiVO4 NPs were synthesized using a modified hydrothermal method through a gradient doping method. Yttrium (III) was used as a phase-stabilizing agent for the tetragonal phase while Mo6+ was used to control the volume of the crystals. The NPs were characterized using scan electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transform Infrared spectroscopy (FTIR), X-Ray diffraction spectroscopy (XRD) and Braunnauer-Emmett -Teller theory (BET) to determine crystal phase, morphology and surface area. It was found that introduction of the dopants and formation of the phase junction lead to a diminished PL spectra indicative of reduced electron-hole recombination. The 10% (m-m) Y-Mo dual-doped multiphase BiVO4 NPs showed the highest electron-hole separation efficiency. However, 15% (m-m) Y-Mo had the least charge separation and due to the formation of recombination centers at high degree s of metal doping. The multiphase systems also showed a red shift in the UV-Vis absorption spectrum. The Mott-Schottky plot obtained from Electro Impedance Spectroscopy confirmed formation of a phase junction in the multiphase systems which resulted in an improvement of the photocurrent to twice that of the pristine BiVO4 NPs for the 10% Y-Mo BiVO4 NPs.The photocurrent for 10% Y-Mo was 0.025 A.cm-2 while that of the pristine BiVO4 NPs was about 0.014 A.cm-2. This increase in photocurrent proves the improvement of charge separation. BET results showed that surface area increased with an increase in the degree of doping and that the 10% Y-Mo dual doped BiVO4 nanomaterials had a surface area of 9.009 m2/g.These NPs were then employed in the photoreduction of Cr6+ in synthetic wastewater first to study the effect of pH, loading of photocatalyst, loading of Cr6+ and temperature. The optimum conditions were then applied for photoreduction in real wastewater samples to study the effect of the water matrix. A photoreactor was used for photoreduction of Cr6+ to Cr3+ and the change in concentration of the Cr6+ was measured using with UV-Vis photometric techniques. It was found that the 10% Y-Mo multiphase BiVO4 had the highest photoreduction efficiency for the Cr6+ of 99.1% in 60 minutes. The reduction efficiency was also found to increase with decrease in pH, initial concentration of Cr6+ and temperature. There was an increase in the photoreduction efficiency with increase in loading of photocatalyst up to a 2g beyond which increase in photocatalyst loading leads to a diminished photoreduction efficiency due to the promotion of aggregation of the Nanoparticles (NPs). The optimum condition for the experiment were set at 10ppm of Cr6+, 25 °C , 1g of photocatalyst and pH of 1. It was also found that the photoreduction of Cr6+ in real wastewater was more efficient reaching 100% in 50 minutes and this was attributed to the presence of hole scavenging species in the wastewater. These results showed that the project was a success. It was recommended that in following studies the multiphase BiVO4 NPs be tested for the photodegradation of organic pollutants. It was also recommended that a comprehensive nanotoxicology study should be undertaken for the multiphase BiVO4 NPs to determine their effect on the environment and on living organisms.
590 $a School code: 2140.
650 4 $a Aqueous solutions. $3 3681511
650 4 $a Desalination. $3 3681473
650 4 $a Phase transitions. $3 3560387
650 4 $a Organic chemicals. $3 3560375
650 4 $a Catalysis. $3 560465
650 4 $a Photocatalysis. $3 737792
650 4 $a Nanoparticles. $3 605747
650 4 $a Efficiency. $3 753744
650 4 $a Heavy metals. $3 552237
653 $a Photoreduction
653 $a Chromium (VI)
653 $a Multi-phase bismuth vanadate (BiVO4)
653 $a Photocatalyst
690 $a 0485
710 2 $a University of Johannesburg (South Africa). $3 3555351
773 0 $t Masters Abstracts International $g 82-11.
790 $a 2140
791 $a M.Sc.
792 $a 2019
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28280586