Graphene Oxide/Zinc Oxide (GO/ZnO) Nanocomposite as a Superior Photocatalyst for Degradation of Methylene Blue (MB)-Process Modeling by Response Surface Methodology (RSM)

Abstract

The photocatalytic performance of graphene oxide/zinc oxide (GO/ZnO) nanocomposite was investigated for degradation of methylene blue (MB) from wastewater and was compared with that of zinc oxide (ZnO), graphene oxide (GO) and carbon nanotube/zinc oxide (CNT/ZnO). The properties of the GO/ZnO nanocomposite were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM and TEM results revealed the nanostructure of the composite. The photocatalytic process was modeled by response surface methodology (RSM), considering four independent factors. The significance of the model was approved by analysis of variance (ANOVA) (determination coefficient R 2 = 0.95, R 2 adj = 0.91). The optimum conditions of the process were found to be at photocatalyst dosage, initial pH, H 2 O 2 concentration and irradiation time of 2.1 g L -1 , 4.5, 3.5 × 10 -4 mol L -1 and 140 min, respectively. The removal of MB over GO/ZnO was 99% under the optimum conditions and was superior than that over GO and CNT/ZnO. According to Pareto analysis of the modeling, the irradiation time and photocatalyst dosage were the most effective factors on the decolorization efficiency of methylene blue, respectively.

Defect Analysis and Testing of Low Power Nanoscale Reversible Decoder using Quantum Dot Cellular Automata

“…1-4 respectively. A peak around 2θ = 10.65° is attributed to graphene oxide sheets and is the characteristic peak of graphene oxide [26]. The average particle size of the crystalline composites and graphene oxide was calculated using Debye -Scherrer equation and are summarized in the Table 1.…”

“…A broad peak at 3366.4 cm -1 shows O-H stretching vibrations of the C-OH groups and water. [26] A peak around ~500 cm -1 (524 cm -1 ) suggests the Zn-O bond vibrations in GO-ZnO composite. EDX analysis was conducted to detect the elemental composition of the composites and graphene oxide.…”

Synthesis of a zinc oxide/graphene hybrid material by the direct thermal decomposition of oxalate

“…Creating strong electronic interaction between nanoscale graphene and ZnO in a composite can significantly modify the ZnO band structure, leading to an array of exciting new properties for the bulk material. For example, they have seen use as photocatalysts [4][5][6][7][8][9][10], sensors [11][12][13][14], capacitors [15][16][17][18][19][20], and as transparent conductive thin-films [21] to name just a few. Equally as diverse as their applications are the methods of synthesizing ZnO/graphene hybrid materials.…”

“…In the interest of developing a synthesis that is as simple, safe, and cost-effective as possible, a solid-state thermal method is preferred due to the minimal equipment requirements, and straight-forward industrial scalability. Nearly all solid-state methods involve the synthesis of pure, nanocrystalline ZnO first, which is then sintered with graphene or graphene oxide, resulting in a material with two clear, distinct phases rather than a cohesive mixture with a more uniform band structure [6,31]. To achieve a more cohesive composite, a methodology involving the thermal decomposition of a zinc-containing precursor in a solid-state solution of graphene, or reduced graphene oxide is preferred.…”

Photocatalytic Properties of Zinc Oxide and Graphene Nanocomposites

“…The interest in using a carbon-based material for this application is because of their unique pore structure, electronic properties, absorptive properties, and acidity. Graphene is favored over other carbon-based materials because it has an ideal sp 2 hybrid carbon nanostructure and surface area (Hosseini & Babaei, 2017). The conjugated structure of graphene allows for the separation of charges during the photocatalytic reaction process, so a combination of ZnO and graphene could potentially have a slower recombination rate than that of ZnO alone (Giem, 2009).…”