Doping TiO2 with CuSO4 enhances visible light photocatalytic activity for organic pollutant degradation

CuO/TiO2/ZnO NPs Anchored Hydrogen Exfoliated Graphene: To Comprehend the Role of Graphene in Catalytic Reduction of p-Nitrophenol

The present study deals with sonochemically in situ synthesis of a novel functional catalyst using hydrogen exfoliated graphene (HEG) supported titanium dioxide (TiO2) and copper sulfate (CuSO4) doped with zinc oxide (ZnO) (abbreviated as Ti/Cu/Zn-HEG). The synthesis of the Ti/Cu/Zn-HEG nanocomposite (NCs) catalyst was confirmed through its characterizations by XRD, SEM-EDX, TEM, XPS, FTIR, and BET methods. It was assessed for catalytic conversion of a model aromatic compound para-nitrophenol (p-NP) in an aqueous solution. The p-NP is a nitroaromatic compound that has a toxic and mutagenic effect. Its removal from the water system is necessary to protect the environment and living being. The newly synthesized Ti/Cu/Zn-HEG NCs were applied for their higher stability and catalytic activity as a potential candidate for reducing p-NP in practice. The operating parameters, such as p-NP concentration, catalyst dosage, and operating time were optimized for 150 ppm, 400 ppm, and 10 min through response surface methodology (RSM) in Design-Expert software to obtain the maximum reduction p-NP up to 98.4% at its normal pH of 7.1 against the controls (using HEG, Ti/Cu-HEG, and Zn-HEG). Analysis of variance of the response suggested the regression equation to be significant for the process with a major impact on catalyst concentration and operating time. The model prediction data (from RSM) and experimental data were corroborated well as reflected through model's low relative error (RE < 0.10), high regression coefficient (R2 > 0.97), and Willmott d-index (dwill-index > 0.95) values.

Nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) as photoactive nanocomposites for water treatment

Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven nanocatalysts were synthesized by using nickel ferrite (NiFe₂O₄) to nanoenable graphene oxide (GO) substrates. GO is an emerging 2D nanomaterial with high conductivity and adsorption properties. Moreover, the electric properties of GO improve photocatalytic performance by promoting charge carrier separation. Results of the characterization of the nickel ferrite nanoenabled graphene oxide (NiFe₂O₄@GO) nanocomposites demonstrate that homogeneous and stable photocatalysts were produced. The as-synthesized nanocatalysts enabled complete decolorization of the colored water matrix in short irradiation times of 150 min using minimal catalyst loading at 0.5 g L^-1. The selective hook and destroy mechanism reduced the competitive effect of co-existing ions in solution. Furthermore, the use of specific scavengers helped to elucidate the degradation mechanisms of organic dye methylene blue by NiFe₂O₄@GO nanocomposites.

Effect of calcination time of a quadruple-element doped titania nanoparticles in the photodegradation of gaseous formaldehyde under blue light irradiation

The photocatalytic degradation of gaseous formaldehyde using Ag/F/N/W-doped titanium dioxide was examined. The photocatalytic reaction was conducted using photocatalysts immobilized on glass tubular reactors illuminated under blue LED lights. Factors affecting gaseous formaldehyde degradation such as photocatalyst's calcination time and dosage, initial formaldehyde concentration, light intensity and operating temperature were studied. Results show that the photocatalytic degradation rate increases with pollutant concentration indicating no mass transfer limitations within the formaldehyde concentration range used. The photodegradation of the formaldehyde using catalyst calcined for 5 h reached ∼88%. The photocatalyst concentration giving the highest degradation rate is found to be 0.10 gL^-1. Which means that upon increasing the concentration of the immobilized photocatalysts will increase its thickness and it may not increase the number of the photo-induced particles. On the other hand, increasing light intensity and operating temperature increased the photocatalytic degradation of gaseous formaldehyde. The maximum light intensity and operating temperature were measured at 25 Wm^-2 and 40 °C, respectively. Langmuir-Hinshelwood kinetic type model was used to describe the photocatalytic reaction. The photocatalytic degradation behavior of gaseous formaldehyde on the modified photocatalyst follows a pseudo-first order rate equation based on a Langmuir-Hinshelwood kinetic type model.