Photocatalytic degradation of the industrial dye yellow tartrazine by commercial ZnO and UV-LED

Copper (Cu) was deposited on two different types of zinc oxide (ZnO), namely commercial ZnO (CZ) and mesoporous zinc oxide (MZ), using a simple electrolysis technique. The catalysts were characterized by XRD, FTIR, BET and UV-Vis DRS. The synergistic effect between Cu, CZ and MZ was tested in the degradation of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation. Cu-MZ exhibited the best performance with 97% degradation compared to MZ, Cu-CZ, CZ and CuO with 80%, 70%, 55% and 49%, respectively. The introduction of Cu in CZ and MZ was found to decrease the band gap energy of ZnO from 3.20 to 3.05 eV and 2.90 to 2.60 eV, respectively. The role of Cu in reducing the band gap energy of Cu-CZ and Cu-MZ probably contributed significantly to the good photocatalytic degradation of 2,4-DCP.

Enhancement of commercial ZnO adsorption and photocatalytic degradation capacity of methylene blue by oxygen vacancy modification: Kinetic study

Novel kinetic modeling of photocatalytic degradation of ethanol and acetaldehyde in air by commercial and reduced ZnO: Effect of oxygen vacancies and humidity

Oxygen vacancy modification of commercial ZnO by hydrogen reduction for the removal of thiabendazole: Characterization and kinetic study

N self-doped ZnO derived from microwave hydrothermal synthesized zeolitic imidazolate framework-8 toward enhanced photocatalytic degradation of methylene blue

Effect of oxygen vacancy modification of ZnO on photocatalytic degradation of methyl orange: A kinetic study

Photocatalytic degradation and mineralization of a malodorous compound (dimethyldisulfide) using a continuous flow reactor

Biogenic synthesis of ZnO from Rubia cordifolia root extract: A study on sono-photocatalytic dye degradation and anti-bacterial assay

Photocatalytic degradation of some organic sulfides as environmental pollutants using titanium dioxide suspension

To provide a low-cost photocatalyst and new methodology for the utilization of waste rice noodle (WRN), a carbon quantum dots/zinc oxide (CQDs/ZnO) composite using WRN as the raw material was synthesized and characterized. The CQDs/ZnO composite based on WRN exhibited a highly efficient photocatalytic degradation effect on various organic pollutants and could be a good alternative for commercial ZnO. For methylene blue, the CQDs/ZnO composite showed a good degradation rate of 99.58% within 40 min, a high degradation rate constant of 0.2630 min−1, and could be recycled and reused for ten photocatalytic cycles without an appreciable decrease in the degradation effect, which was much better than that of commercial ZnO. The resulting CQDs/ZnO composite also displayed a nice photocatalytic degradation effect on other common organic pollutants, such as malachite green, methyl violet, basic fuchsin, rhodamine B, aniline and tetracycline. In particular, it could achieve excellent photocatalytic degradation on malachite green with an extremely high degradation rate constant of 1.9260 min−1. Besides, the CQDs/ZnO composite could also be used to control the pollution of tetracycline or aniline. The introduction of CQDs based on WRN to ZnO resulted in efficient electron–hole pair separation and enabled more photogenerated electrons to reduce O2 and more photogenerated holes to oxidize H2O, which caused stronger abilities in producing radicals (such as O2˙− and ˙OH) and a better photocatalytic degradation effect to organic pollutants.

Ag-N-codoped zinc oxide nanoparticles were synthesized by a one-step impregnation of Ag in N-doped ZnO nanoparticles. The morphologies and structures of the as-synthesized nanomaterials were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis spectrophotometric techniques. Photocatalytic degradation of methyl red dye using synthesized photocatalysts was studied under solar as well as UV irradiations. Modified zinc oxide photocatalysts showed higher photocatalytic activity compared to pure zinc oxide both under solar as well as UV irradiations. Calcined zinc oxide shows better photocatalytic activity than commercial zinc oxide under both solar and UV irradiations. Highest catalytic activity of Ag-N co-doped zinc oxide (ANZ) among the undoped, Ag-doped and N-doped photocatalysts was attributed to the lower rate of recombination of the photogenerated electrons and holes as well as its lower band gap energy. Photocatalytic degradation of methyl red dye follows pseudo first order kinetics for all the nanoparticles so-obtained. KEY WORDS: Nanoparticles, Photocatalysis, Zinc oxide, Impregnation, Methyl red Bull. Chem. Soc. Ethiop. 2013, 27(2), 221-232DOI: http://dx.doi.org/10.4314/bcse.v27i2.7

Effectiveness of zinc oxide-assisted photocatalysis for concerned constituents in reclaimed wastewater: 1,4-Dioxane, trihalomethanes, antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs)

5 wt.% of noble metals (Ag and Cu) were introduced onto commercial zinc oxide (ZnO) via an electrochemical method. The catalysts were characterised by XRD, FTIR, BET and UV-Vis DRS. The introduction of noble metals has increased the surface area and decreased the band gap of the catalysts which contributed to excellent photocatalytic performance. The performance on photodegradation of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation was highest with 5% Cu-ZnO (82%) followed by 5% Ag-ZnO (79%) and ZnO (55%). The lowest band gap energy with the largest surface area of 5% Cu-ZnO probably contributed significantly to the best photocatalytic degradation of 2,4-DCP. In evaluating an aqueous phase for photocatalytic reaction, the pH solution is an important regulating parameter. Therefore, the effect of pH on the degradation of 2,4-DCP by 5% Cu-ZnO and 5% Ag-ZnO was examined in this work. Besides, the optimum pH for the reaction is usually determined by the catalyst's points zero charge (pHPZC). The pHPZC of 5% Cu-ZnO and 5% Ag-ZnO were found to be 4.4 and 4.5, respectively. Thus, both catalysts worked the best in an acidic condition (pH 3).

An efficient pilot scale solar treatment method for dye industry effluent using nano-ZnO

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