Mechanism and Purification Effect of Photocatalytic Wastewater Treatment Using Graphene Oxide-Doped Titanium Dioxide Composite Nanomaterials

One-Pot Synthesis of Cellulose-Based Carbon Aerogel Loaded with TiO2 and g-C3N4 and Its Photocatalytic Degradation of Rhodamine B

A cellulose-based carbon aerogel (CTN) loaded with titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) was prepared using sol-gel, freeze-drying, and high-temperature carbonization methods. The formation of the sol-gel was carried out through a one-pot method using refining papermaking pulp, tetrabutyl titanate, and urea as raw materials and hectorite as a cross-linking and reinforcing agent. Due to the cross-linking ability of hectorite, the carbonized aerogel maintained a porous structure and had a large specific surface area with low density (0.0209 g/cm3). The analysis of XRD, XPS, and Raman spectra revealed that the titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) were uniformly distributed in the CTN, while TEM and SEM observations demonstrated the uniformly distributed three-dimensional porous structure of CTN. The photocatalytic activity of the CTN was determined according to its ability to degrade rhodamine B. The removal rate reached 89% under visible light after 120 min. In addition, the CTN was still stable after five reuse cycles. The proposed catalyst exhibits excellent photocatalytic performance under visible light conditions.

Novel TiO2/GO/M-MMT nano-heterostructured composites exhibiting high photocatalytic activity

This study proposed a technique to enhance the photocatalytic properties of TiO2 using graphene oxide (GO) and modified Montmorillonite (M-MMT). TiO2/GO/M-MMT nano-heterostructured composites were prepared via hydrothermal and co-precipitation. The photocatalytic performance was evaluated by investigating the photodegradation rate and absorption behavior of methyl orange (MO) under visible light irradiation. The results showed that TiO2/GO/M-MMT heterojunction exhibited excellent photocatalytic degradation performance, as the degradation rate of MO was observed to be 99.3% within 150 min. The density of adsorbed MO decreased by 62.1% after 210 min of dark adsorption using the TiO2/GO/M-MMT composite, which was significantly higher than that achieved using M-MMT, GO/M-MMT, and TiO2/M-MMT. The nano-heterostructure increased the effective interface between TiO2, GO, and MMT, which increased the charge transfer ability and prolonged the electron-hole separation time. Therefore, the results of this study can be used to design novel photocatalysts to eradicate environmental pollutants.

Optimization and biosynthesis of calcined chicken eggshell doped titanium dioxide photocatalyst based nanoparticles for wastewater treatment

Abstract

This study presents, biosynthesis of calcinated eggshell (CES) doped with Titanium dioxide (TiO2,) photocatalyst for photodegradation of methylene blue from synthetic wastewater. The influence of three independent variables for improving photodegradation efficiency was investigated and optimized using response surface methodology of Box–Behnken Design on the removal of methylene blue using the calcined chicken eggshells (CES) doped with titanium dioxide. The experimental result showed that 95.8% degradation efficiency of methylene blue by prepared photocatalyst at a contact time of 180 min, initial concentration of methylene blue of 10 ppm, and calcined eggshells (CES) doped with titanium dioxide dose of 2.5 g/L. The synthesized photocatalyst was characterized by Fourier-transform infrared spectroscopy, UV-spectrometer, and X-ray diffractometer and UV–vis Spectroscopy for determined their functional group, structure, and bandgap energy respectively. Their results depict the calcined eggshell doped with titanium dioxide photocatalyst is a promising option for the degradation of methylene blue from industrial wastewater under the stated condition.

Highlights

Solvothermal Synthesis of ZnO Nanoparticles for Photocatalytic Degradation of Methyl Orange and p-Nitrophenol

The photocatalytic degradation of organic pollutants is an effective method of controlling environmental pollution. ZnO nanoparticles (ZnO NPs) were prepared by the solvothermal method and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–visible diffuse reflectance spectroscopy (UV–Vis DRS). The results showed that the ZnO NPs had a uniform size of 25–40 nm, hexagonal wurtzite structure, and a band gap of 2.99 eV. The photocatalytic degradation of methyl orange (MO) and p-nitrophenol (PNP) was used as a model reaction to evaluate the photocatalytic activity of ZnO NPs. The photocatalytic degradation rates (pseudo-first-order kinetics) of MO and PNP were 92% (0.0128 min−1) and 56.2% (0.0042 min−1), respectively, with a 25 W ultraviolet lamp, MO/PNP concentration = 20 mg/L, ZnO NPs dose = 1.5 g/L, and time = 180 min. The photocatalytic mechanism of ZnO NPs and degradation pathways of MO and PNP were also proposed. The results provide valuable information and guidance for the treatment of wastewater via photocatalytic methods.