Design and Preparation of Biomass-Derived Activated Carbon Loaded TiO2 Photocatalyst for Photocatalytic Degradation of Reactive Red 120 and Ofloxacin.

The design and development of novel photocatalysts for treating toxic substances such as industrial waste, dyes, pesticides, and pharmaceutical wastes remain a challenging task even today. To this end, a biowaste pistachio-shell-derived activated carbon (AC) loaded TiO2 (AC-TiO2) nanocomposite was fabricated and effectively utilized towards the photocatalytic degradation of toxic azo dye Reactive Red 120 (RR 120) and ofloxacin (OFL) under UV-A light. The synthesized materials were characterized for their structural and surface morphology features through various spectroscopic and microscopic techniques, including high-resolution transmission electron microscope (HR-TEM), field emission scanning electron microscope (FE-SEM) along with energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, photoluminescence spectra (PL) and BET surface area measurements. AC-TiO2 shows enhanced photocatalytic activity compared to bare TiO2 due to the change in the bandgap energy and effective charge separation. The degradation rate of dyes was affected by the bandgap of the semiconductor, which was the result of the deposition weight percentage of AC onto the TiO2. The presence of AC influences the photocatalytic activity of AC-TiO2 composite towards RR 120 and OFL degradation. The presence of heteroatoms-enriched AC enhances the charge mobility and suppresses the electron-hole recombination in AC-TiO2 composite, which enhances the photocatalytic activity of the composite. The hybrid material AC-TiO2 composite displayed a higher photocatalytic activity against Reactive Red 120 and ofloxacin. The stability of the AC-TiO2 was tested against RR 120 dye degradation with multiple runs. GC-MS analyzed the degradation intermediates, and a suitable degradation pathway was also proposed. These results demonstrate that AC-TiO2 composite could be effectively used as an ecofriendly, cost-effective, stable, and highly efficient photocatalyst.

Solar light-driven CeVO4/ZnO nanoheterojunction for the mineralization of Reactive Orange 4.

In this study, we synthesized CeVO4/ZnO nanoheterojunction photocatalyst through hydrothermal-precipitation method. The prepared photocatalyst was characterized by Fourier transform infrared analysis (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) with elemental color mapping (ECM), high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern, UV-vis diffuse reflection spectroscopy (UV-vis-DRS), BET, and photoluminescence (PL) spectroscopy. The BET surface area of CeVO4/ZnO is 10.50 m2/g. The photocatalytic activity of CeVO4/ZnO nanoheterojunction under solar light was investigated for the degradation of Reactive Orange 4 (RO 4). CeVO4/ZnO has been found to be more effective for mineralization of RO 4 than the prepared ZnO at neutral pH. The addition of TBA (•OH scavenger) contributes a significant decrease in the photodegradation efficiently of the catalyst. Chemical oxygen demand (COD) measurements confirmed the complete mineralization of RO 4. In addition, it found that the photocatalyst was stable and reusable. Graphical abstract.

Bio-based (chitosan/PVA/ZnO) nanocomposites film: Thermally stable and photoluminescence material for removal of organic dye.

Preparation of hitherto unreported chitosan/poly(vinyl alcohol)/ZnO nanocomposites film (designated as CS/PVA/ZnO) as an efficient bio-based nanocomposites is carried out by a greener approach involving mixing, solution casting and solvent evaporation. Synthesized chitosan-based nanocomposites films are characterized by various analytical techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The photoluminescent properties of CS/PVA/ZnO films are thoroughly studied and compared with CS/PVA. The outcome suggested that the addition of ZnO nanoparticles increased the intensities and red shifting with respect to CS/PVA. The toxicity of chitosan-based nanocomposites films was examined by MTT assay using the NIH3T3 cells. The viability of chitosan-based nanocomposites films was found to be better than native chitosan and PVA films. Furthermore, the adsorption property of prepared chitosan-based nanocomposites films was tested for the removal of AB 1 dye.

Chemically modified amino porphyrin/TiO2 for the degradation of Acid Black 1 under day light illumination.

In this paper, for the first time, chemically modified 5,10,15,20-meso-tetra-(para-amino)-phenyl-porphyrin/TiO2 (TPAPP/TiO2) was prepared and used for the degradation of an azo dye Acid Black 1 (AB 1) under direct sunlight. Initially, TiO2 was prepared by sol-gel method. Before making a TPAPP/TiO2 composite, the surface modification of TiO2 was carried out with glycidoxypropyltrimethoxy silane (GPTMS) which acts as a coupling agent. This is an epoxy terminated silane and could easily bond to the amino group of TPAPP through epoxy cleavage. The formation of TPAPP/TiO2 was confirmed by different characterization techniques such as FT-IR, XRD, SEM and DRS. The photocatalytic activity of TiO2 was highly influenced by TPAPP. A mechanism was proposed for AB 1 degradation by TPAPP/TiO2 under sun light.

Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7.

Fe(III) immobilized fire clay (Fe-FC) was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7 (AV 7) under natural sunlight. The 26% ferric nitrate loaded fire clay was found to be most efficient. The experimental conditions such as solution pH, H2O2 concentration for efficient degradation of AV 7 have been determined. Unlike Fenton catalyst, Fe-FC is photoactive over a wide pH range of 3-7. This catalyst was found to be stable and reusable. The GC-MS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6-triol, 8-aminonaphthalene-1,2,3,6-tetrol, 2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/ 2-aminobenzene-1,4-diol as intermediates. The 26% ferric nitrate loaded fire clay was characterized by XRD, ICP-AES, BET surface area, FT-IR, SEM-EDS and UV-DRS studies.