Highly Efficient Photocatalyst Fabricated from the Chemical Recycling of Iron Waste and Natural Zeolite for Super Dye Degradation

Zeolite 13X incorporated with Zn-Ce oxide nanocatalyst for removal of Reactive Red 120 dye: RSM-based approach

In this study, the photocatalytic removal of Reactive Red 120 (RR120) dye was examined using zeolite 13X incorporated with Zn-Ce under UV irradiation. The synthesis of Zn-Ce nanoparticles incorporated with zeolite 13X was conducted through the co-precipitation method, and the features of the prepared nanocatalyst were analyzed using various techniques. The SEM and BET analyses indicated successful incorporation of ZnO-Ce oxides on the surface of zeolite 13X and a specific surface area of 359.39 m2/gm, respectively. Further, the average size of crystal grains was 28 nm. The response surface methodology (RSM) approach was employed to optimize operating parameters. The quadratic model suggested by the RSM approach, characterized by a high regression coefficient (R2 = 0.9632), indicates a high level of reliability. Moreover, under optimal conditions (catalyst loading of 4 mg, pH of 3, H2O2 amount of 0.2 mL, UV power of 25 W, and reaction time of 60 min), the highest RR120 dye removal percentage was 99.97%. Kinetic data indicated an increase in the reaction rate constant from 0.0631 to 0.1796 min-1. The zeolite 13X incorporated with Zn-Ce photocatalyst exhibited excellent stability over 5 cycles, with only a 5.50% decrease in RR120 dye removal yield. This study demonstrates the promising potential of zeolite 13X incorporated with Zn-Ce nanoparticles for the removal of RR120 dye from aqueous suspension.

Application of zeolite based nanocomposites for wastewater remediation: Evaluating newer and environmentally benign approaches

The presence of heavy metal ions and emerging pollutants in water poses a great risk to various biological ecosystems as a result of their high toxicity. Consequently, devising efficient and environmentally friendly methods to decontaminate these waters is of high interest to many researchers around the world. Among the varied water treatment and desalination means, adsorption and photocatalysis have been widely employed. However, the discussion and analysis of the use of zeolite-based composites as adsorbents are somehow minimal. The porous aluminosilicates (zeolites) are excellent candidates in wastewater treatment owing to various mechanisms of pollutants removal that they possess. The purpose of this review is thus to provide a synopsis of the current developments in the fabrication and application of nanocomposites based on zeolite as adsorbents and photocatalysts for the extraction of heavy metals, dyes and emerging pollutants from wastewaters. The review goes on to look into the effect of weight ratio on photocatalyst, photodegradation pathways, and various factors that influence photocatalysis and adsorption.

Photocatalytic Degradation of Methyl Orange and Methylene Blue Dyes by Engineering the Surface Nano-Textures of TiO2 Thin Films Deposited at Different Temperatures via MOCVD

TiO₂ thin films were deposited on quartz substrates by metal-organic chemical vapor deposition (MOCVD) at temperatures of 250, 350, and 450 °C. X-ray diffraction (XRD) data revealed the production of a pure anatase phase, a decrease in crystallite size, and a textural change as deposition temperature increased. Atomic force microscopy (AFM) was used to study the morphological properties and confirm XRD results. UV-Vis.-NIR spectroscopy was used to investigate the optical properties of the samples. The effect of deposition temperature on wettability was investigated using contact angle measurements. Sunlight photocatalytic properties increased with the increase in deposition temperature for methyl orange and methylene blue. Films were post-annealed at 500 °C for 2 h. The effect of annealing on all the above-mentioned properties was explored. The kinetic analysis demonstrated superb agreement with the kinetic pseudo-first-order model. The rate of photocatalytic degradation of MB was ~8, 13, and 12 times that of MO using 250, 350, and 450 °C deposited films, respectively. Photodegradation was found to depend on the specific surface area, type of pollutant, and annealing temperature.

Design and Characterization of Zeolite/Serpentine Nanocomposite Photocatalyst for Solar Hydrogen Generation

In this work, a low-cost, high-yield hydrothermal treatment was used to produce nanozeolite (Zeo), nanoserpentine (Serp), and Zeo/Serp nanocomposites with weight ratios of 1:1 and 2:1. At 250 °C for six hours, the hydrothermal treatment was conducted. Various methods are used to explore the morphologies, structures, compositions, and optical characteristics of the generated nanostructures. The morphological study revealed structures made of nanofibers, nanorods, and hybrid nanofibril/nanorods. The structural study showed clinoptilolite monoclinic zeolite and antigorite monoclinic serpentine with traces of talcum mineral and carbonates. As a novel photoelectrochemical catalyst, the performance of the Zeo/Serp (2:1) composite was evaluated for solar hydrogen generation from water splitting relative to its constituents. At -1 V, the Zeo/Serp (2:1) composite produced a maximum current density of 8.44 mA/g versus 7.01, 6.74, and 6.6 mA/g for hydrothermally treated Zeo/Serp (1:1), Zeo, and Serp, respectively. The Zeo/Serp (2:1) photocatalysts had a solar-to-hydrogen conversion efficiency (STH) of 6.5% and an estimated hydrogen output rate of 14.43 mmole/h.g. Consequently, the current research paved the way for low-cost photoelectrochemical catalytic material for efficient solar hydrogen production by water splitting.

Green Synthesis of CS-TiO2 NPs for Efficient Photocatalytic Degradation of Methylene Blue Dye

The development of a non-malignant and sustainable treatment approach for eradicating mephitic organic dyes from freshwater resources is a daunting task. In a similar vein, the current work investigates the mitigation of methylene blue (MB) dye utilizing titanium dioxide nanoparticles (CS-TiO₂ NPs) synthesized using cannabis sativa (bhang) leaf extract via a greener approach. The CS-TiO₂ NPs are well characterized through XRD, FE-SEM, HR-TEM, UV-Vis spectroscopy, FTIR spectroscopy, and EDS spectroscopy. Microscopic studies confirm that the average particle size distribution of the individual particles was found to be in the range of 12.5 ± 1.5 nm, whereas the average size of the CS-TiO₂ NPs aggregates is 24.5 ± 11.5 nm. Additionally, the synthesized CS-TiO₂ NPs manifested remarkable photocatalytic degradation potential against methylene blue dye with a degradation efficiency of 98.2% and an apparent rate constant of 0.0398 min⁻¹. As a result, this research offers a green/sustainable alternative for water purification.

Enhanced Photocatalytic Activity of Zn-Al Layered Double Hydroxides for Methyl Violet and Peat Water Photooxidation

Zn-Al Layered Double Hydroxides (Zn-Al LDHs) and its calcined form were successfully prepared and utilized for the removal of methyl violet (MV) and treatment of peat water by photocatalytic oxidation. The research was aimed to evaluate the effect of calcination to Zn-Al LDHs for the effect on the physicochemical character and the capability as a photocatalyst. The characterization of the samples was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmet–Teller specific surface area (BET), and X-ray photoelectron spectroscopy (XPS). The results showed that the increased BET specific surface area along with the enhanced porous structure was achieved by the calcination procedure, which is associated with the enhanced interlayer space of d₀₀₃ identified by XRD analysis. Thermal conversion showed an influence to the increased band gap energy from 3.10 eV in the uncalcined Zn-Al LDHs into 3.16 eV for the calcined material. These character changes contributed to the enhanced photocatalytic activity of the Zn-AL LDHs by calcination, which was proposed and verified by experiments. It was observed that photocatalytic activity of the material for MV gave about a 45.57% removal of MV and a 68% removal for the natural organic material of the peat water.

Fabrication of TiO2/NiO p-n Nanocomposite for Enhancement Dye Photodegradation under Solar Radiation

A p-n nanocomposite based on TiO2 nanotubes (NTs) and NiO nanoparticles (NPs) was designed and optimized in this study to improve the photocatalytic performance of methylene blue (MB). The hydrothermal technique has been used to produce TiO2/NiO nanocomposites with different NiO NPs weight ratios; 1TiO2:1NiO, 1TiO2:2NiO, and 1TiO2:3NiO. The crystal phase, chemical composition, optical properties, and morphology of TiO2/NiO were explored by various techniques. TiO2 NTs have a monoclinic structure, while NiO NPs have a cubic structure, according to the structural study. The bandgap of TiO2 NTs was reduced from 3.54 eV to 2.69 eV after controlling the NiO NPs weight ratio. The TiO2/2NiO nanocomposite showed the best photodegradation efficiency. Within 45 min of solar light irradiation, the efficiency of MB dye degradation using TiO2/2NiO hits 99.5% versus 73% using pure TiO2 NTs. Furthermore, the catalytic photodegradation efficiency did not deteriorate significantly even after five reusability cycles, intimating the high stability of the TiO2/2NiO nanocomposite. This suggests that the loading of NiO NPs into TiO2 NTs lowers the recombination of photo-produced electron/hole pairs and enlarged solar spectral response range, which results in improved photocatalytic activity. The mechanism of charge transfer in the TiO2/NiO and kinetic models were discussed for the photodegradation of MB.