scholarly journals Removal of Organic Dyes from Water and Wastewater Using Magnetic Ferrite-Based Titanium Oxide and Zinc Oxide Nanocomposites: A Review

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1543
Author(s):  
António B. Mapossa ◽  
Washington Mhike ◽  
José L. Adalima ◽  
Shepherd Tichapondwa
Keyword(s):  
Zinc Oxide ◽  
Visible Light ◽  
Titanium Oxide ◽  
Organic Dyes ◽  
Organic Pollutant ◽  
Synthesis Method ◽  
Degradation Efficiency ◽  
Commercial Application ◽  
Synthesis Methods ◽  
Subsequent Formation

Heterogeneous photocatalysis using titanium dioxide (TiO2) and zinc oxide (ZnO) has been widely studied in various applications, including organic pollutant remediation in aqueous systems. The popularity of these materials is based on their high photocatalytic activity, strong photosensitivity, and relatively low cost. However, their commercial application has been limited by their wide bandgaps, inability to absorb visible light, fast electron/hole recombination, and limited recyclability since the nanomaterial is difficult to recover. Researchers have developed several strategies to overcome these limitations. Chief amongst these is the coupling of different semi-conductor materials to produce heterojunction nanocomposite materials, which are both visible-light-active and easily recoverable. This review focuses on the advances made in the development of magnetic ferrite-based titanium oxide and zinc oxide nanocomposites. The physical and magnetic properties of the most widely used ferrite compounds are discussed. The spinel structured material had superior catalytic and magnetic performance when coupled to TiO2 and ZnO. An assessment of the range of synthesis methods is also presented. A comprehensive review of the photocatalytic degradation of various priority organic pollutants using the ferrite-based nanocomposites revealed that degradation efficiency and magnetic recovery potential are dependent on factors such as the chemical composition of the heterojunction material, synthesis method, irradiation source, and structure of pollutant. It should be noted that very few studies have gone beyond the degradation efficiency studies. Very little information is available on the extent of mineralization and the subsequent formation of intermediate compounds when these composite catalysts are used. Additionally, potential degradation mechanisms have not been adequately reported.

scholarly journals A visible-light phototransistor based on the heterostructure of ZnO and TiO2 with trap-assisted photocurrent generation

RSC Advances ◽  
2021 ◽  
Vol 11 (20) ◽  
pp. 12051-12057
Author(s):  
Byung Jun Kim ◽  
Jun Hyung Jeong ◽  
Eui Young Jung ◽  
Tae Yeon Kim ◽  
Sungho Park ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Visible Light ◽  
Titanium Oxide ◽  
Photocurrent Generation

Visible-light phototransistors have been fabricated based on the heterojunction of zinc oxide (ZnO) and titanium oxide (TiO2).

scholarly journals MWCNTs/Ag-ZnO nanocomposite for efficient photocatalytic degradation of congo red

2020 ◽  
Vol 34 (1) ◽  
pp. 55-66
Author(s):  
Amogne W. Yibeltal ◽  
Belete B. Beyene ◽  
Shimelis Admassie ◽  
Abi M. Taddesse
Keyword(s):  
Zinc Oxide ◽  
Visible Light ◽  
Rate Constant ◽  
Congo Red ◽  
Organic Pollutant ◽  
Order Rate Constant ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Role Of Light

Three nanomaterials namely, zinc oxide (ZC), silver-doped zinc oxide (AZ) and multi-walled carbon nanotubes coupled with silver doped zinc oxide nanocomposite (MWAZ) were synthesized, characterized and employed for photo degradation of an organic pollutant, congo red (CR). The photocatalytic activity study showed efficient degradation of CR upon irradiation with UV and visible light in the order of MWAZ > AZ > ZC > Commercial ZnO (ZCO). Percentage photodegradation of 99% and a pseudo 1st order rate constant of 2.3 x 10-2 min-1 were achieved by MWAZ as a catalyst under visible light irradiation, implying photo- sensitizing ability of MWCNTs and the capability of MWCNTs to hinder recombination of photogenerated holes and electrons. The control experiment in the dark condition gave only 7.9% of degradation efficiency and 5.56 x 10-4 min-1 rate constant, implying the significant role of light source for catalytic degradation of CR.   Bull. Chem. Soc. Ethiop. 2020, 34(1), 55-66. DOI: https://dx.doi.org/10.4314/bcse.v34i1.5

scholarly journals PREPARATION OF TEMPO-CELLULOSE NANOFIBER/ZINC OXIDE AS ANTIMICROBIAL AND METHYLENE BLUE PHOTO-DEGRADING NANOCOMPOSITE

2021 ◽  
Vol 55 (3-4) ◽  
pp. 365-373
Author(s):  
MOHAMED EL-SAKHAWY ◽  
AHMED SALAMA ◽  
AHMED K. EL-ZIATY ◽  
HAZEM HASSAN
Keyword(s):  
Methylene Blue ◽  
Zinc Oxide ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Environmental Remediation ◽  
Organic Dyes ◽  
Cellulose Nanofibers ◽  
Light Irradiation ◽  
Order Kinetic ◽  
Catalytic Material

"Photo-catalytic degradation of organic dyes in aquatic environments under visible light irradiation affords an efficient and economic technique for environmental remediation. TEMPO-oxidized cellulose nanofibers/zinc oxide nanocomposite (TEMPO-CNF/ZnO) was prepared through oxidation of cellulose pulp, followed by zinc oxide precipitation in the presence of oxidized fibers. TEMPO-CNF/ZnO was characterized by different techniques. The degradation rate of methylene blue (MB) by TEMPO-CNF/ZnO was gradually increased with increasing pH and the degradation reached 86% within 340 minutes at pH 7. The kinetic study showed that the pseudo-first-order kinetic best fitted the photo-catalytic process. A mechanism was proposed for the degradation of MB using TEMPO-CNF/ZnO under visible light irradiation. TEMPO-CNF/ZnO showed high antibacterial activity against S. aureus and E. coli. Thus, the TEMPO-CNF/ZnO nanocomposite has been demonstrated to be an effective photo-catalytic material for degrading MB under visible light irradiation."

Rhodamines as Photocatalyst in Organic Synthesis

2020 ◽  
Vol 07 ◽  
Author(s):  
Avik K. Bagdi ◽  
Papiya Sikdar
Keyword(s):  
Visible Light ◽  
Organic Synthesis ◽  
Organic Dyes ◽  
Transition Metal Catalysts ◽  
Visible Light Photocatalysis ◽  
Eosin Y ◽  
Organic Transformations ◽  
The Sustainable Development ◽  
Mechanistic Pathway ◽  
Green Model

Abstract:: Organic synthesis under environment friendly conditions has great impact in the sustainable development. In this context, visible light photocatalysis has emerged as a green model as this offers an energy-efficient pathway towards the organic transformation. Different transition-metal catalysts (Ir-, Ru-, Cu- etc) and organic dyes (eosin Y, rose bengal, methylene blue etc) are well-known photocatalysts in organic synthesis. Apart from the well-known organophotoredox catalysts, rhodamines (Rhodamine B and Rhodamine 6G) have been also employed as efficient photocatalysts for different organic transformations. In this review, we will focus on the photocatalysis by rhodamines in organic synthesis. Mechanistic pathway of the methodologies will also be discussed. We believe this review will stimulate the employment of rhodamines in the visible light photocatalysis for efficient organic transformations in the future.

Electrospun-based TiO2 nanofibers for organic pollutant photodegradation: a comprehensive review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Khee Chung Hui ◽  
Hazwani Suhaimi ◽  
Nonni Soraya Sambudi
Keyword(s):  
Visible Light ◽  
Organic Pollutants ◽  
Organic Pollutant ◽  
Hollow Fibers ◽  
Promising Alternative ◽  
Tio2 Nanofibers ◽  
As Doping ◽  
Secondary Pollutants ◽  
Photocatalytic Reactors ◽  
Light Area

Abstract Titanium dioxide (TiO2) is commonly used as a photocatalyst in the removal of organic pollutants. However, weaknesses of TiO2 such as fast charge recombination and low visible light usage limit its industrial application. Furthermore, photocatalysts that are lost during the treatment of pollutants create the problem of secondary pollutants. Electrospun-based TiO2 fiber is a promising alternative to immobilize TiO2 and to improve its performance in photodegradation. Some strategies have been employed in fabricating the photocatalytic fibers by producing hollow fibers, porous fibers, composite TiO2 with magnetic materials, graphene oxide, as well as doping TiO2 with metal. The modification of TiO2 can improve the absorption of TiO2 to the visible light area, act as an electron acceptor, provide large surface area, and promote the phase transformation of TiO2. The improvement of TiO2 properties can enhance carrier transfer rate which reduces the recombination and promotes the generation of radicals that potentially degrade organic pollutants. The recyclability of fibers, calcination effect, photocatalytic reactors used, operation parameters involved in photodegradation as well as the commercialization potential of TiO2 fibers are also discussed in this review.

scholarly journals Eco-Friendly Colloidal Aqueous Sol-Gel Process for TiO2 Synthesis: The Peptization Method to Obtain Crystalline and Photoactive Materials at Low Temperature

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 768
Author(s):  
Julien G. Mahy ◽  
Louise Lejeune ◽  
Tommy Haynes ◽  
Stéphanie D. Lambert ◽  
Raphael Henrique Marques Marcilli ◽  
...  
Keyword(s):  
Organic Pollutant ◽  
Sol Gel ◽  
Synthesis Method ◽  
Specific Treatment ◽  
High Specific Surface Area ◽  
Crystalline Phases ◽  
Tio2 Photocatalysts ◽  
Tio2 Anatase ◽  
Synthesis Parameters ◽  
Calcination Step

This work reviews an eco-friendly process for producing TiO2 via colloidal aqueous sol–gel synthesis, resulting in crystalline materials without a calcination step. Three types of colloidal aqueous TiO2 are reviewed: the as-synthesized type obtained directly after synthesis, without any specific treatment; the calcined, obtained after a subsequent calcination step; and the hydrothermal, obtained after a specific autoclave treatment. This eco-friendly process is based on the hydrolysis of a Ti precursor in excess of water, followed by the peptization of the precipitated TiO2. Compared to classical TiO2 synthesis, this method results in crystalline TiO2 nanoparticles without any thermal treatment and uses only small amounts of organic chemicals. Depending on the synthesis parameters, the three crystalline phases of TiO2 (anatase, brookite, and rutile) can be obtained. The morphology of the nanoparticles can also be tailored by the synthesis parameters. The most important parameter is the peptizing agent. Indeed, depending on its acidic or basic character and also on its amount, it can modulate the crystallinity and morphology of TiO2. Colloidal aqueous TiO2 photocatalysts are mainly being used in various photocatalytic reactions for organic pollutant degradation. The as-synthesized materials seem to have equivalent photocatalytic efficiency to the photocatalysts post-treated with thermal treatments and the commercial Evonik Aeroxide P25, which is produced by a high-temperature process. Indeed, as-prepared, the TiO2 photocatalysts present a high specific surface area and crystalline phases. Emerging applications are also referenced, such as elaborating catalysts for fuel cells, nanocomposite drug delivery systems, or the inkjet printing of microstructures. Only a few works have explored these new properties, giving a lot of potential avenues for studying this eco-friendly TiO2 synthesis method for innovative implementations.

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