Highly efficient decomposition of organic dye by aqueous-solid phase transfer and in situ photocatalysis using hierarchical copper phthalocyanine hollow spheres

Advanced oxidation process for the treatment of industrial wastewater: A review on strategies, mechanisms, bottlenecks and prospects

Due to its complex and, often, highly contaminated nature, treating industrial wastewater poses a significant environmental problem. Many of the persistent pollutants found in industrial effluents cannot be effectively removed by conventional treatment procedures. Advanced Oxidation Processes (AOPs) have emerged as a promising solution, offering versatile and effective means of pollutant removal and mineralization. This comprehensive review explores the application of various AOP strategies in industrial wastewater treatment, focusing on their mechanisms and effectiveness. Ozonation (O3): Ozonation, leveraging ozone (O3), represents a well-established AOP for industrial waste water treatment. Ozone's formidable oxidative potential enables the breakdown of a broad spectrum of organic and inorganic contaminants. This paper provides an in-depth examination of ozone reactions, practical applications, and considerations involved in implementing ozonation. UV/Hydrogen Peroxide (UV/H2O2): The combination of ultraviolet (UV) light and hydrogen peroxide (H2O2) has gained prominence as an AOP due to its ability to generate hydroxyl radicals (ȮH), highly efficient in pollutant degradation. The review explores factors influencing the efficiency of UV/H2O2 processes, including H2O2 dosage and UV radiation intensity. Fenton and Photo-Fenton Processes: Fenton's reagent and Photo-Fenton processes employ iron ions and hydrogen peroxide to generate hydroxyl radicals for pollutant oxidation. The paper delves into the mechanisms, catalyst selection, and the role of photoactivation in enhancing degradation rates within the context of industrial wastewater treatment. Electrochemical Advanced Oxidation Processes (EAOPs): EAOPs encompass a range of techniques, such as electro-Fenton and anodic oxidation, which employ electrode reactions to produce ȮH radicals. This review explores the electrochemical principles, electrode materials, and operational parameters critical for optimizing EAOPs in industrial wastewater treatment. TiO2 Photocatalysis (UV/TiO2): Titanium dioxide (TiO2) photocatalysis, driven by UV light, is examined for its potential in industrial wastewater treatment. The review investigates TiO2 catalyst properties, reaction mechanisms, and the influence of parameters like catalyst loading and UV intensity on pollutant removal. Sonolysis (Ultrasonic Irradiation): High-frequency ultrasound-induced sonolysis represents a unique AOP, generating ȮH radicals during the formation and collapse of cavitation bubbles. This paper delves into the physics of cavitation, sonolytic reactions, and optimization strategies for industrial wastewater treatment. This review offers a critical assessment of the applicability, advantages, and limitations of these AOP strategies in addressing the diverse challenges posed by industrial wastewater. It emphasizes the importance of selecting AOPs tailored to the specific characteristics of industrial effluents and outlines potential directions for future research and practical implementation. The integrated use of these AOPs, when appropriately adapted, holds the potential to achieve sustainable and efficient treatment of industrial wastewater, contributing significantly to environmental preservation and regulatory compliance.

Photocatalytic Activity Induced by Metal Nanoparticles Synthesized by Sustainable Approaches: A Comprehensive Review

Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Among many techniques that are employed toward the production of nanoparticles, synthesis using green technologies is the simplest and environment friendly. Nanoparticles produced from plant extracts have become a very popular subject of study in recent decades due to their diverse advantages such as low-cost synthesis, product stability, and ecofriendly protocols. These merits have prompted the development of nanoparticles from a variety of sources, including bacteria, fungi, algae, proteins, enzymes, etc., allowing for large-scale production with minimal contamination. However, nanoparticles obtained from plant extracts and phytochemicals exhibit greater reduction and stabilization and hence have proven the diversity of properties, like catalyst/photocatalyst, magnetic, antibacterial, cytotoxicity, circulating tumor deoxy ribo nucleic acid (CT-DNA) binding, gas sensing, etc. In the current scenario, nanoparticles can also play a critical role in cleaning wastewater and making it viable for a variety of operations. Nano-sized photocatalysts have a great scope toward the removal of large pollutants like organic dyes, heavy metals, and pesticides in an eco-friendly and sustainable manner from industrial effluents. Thus, in this review article, we discuss the synthesis of several metal nanoparticles using diverse plant extracts, as well as their characterization via techniques like UV–vis (ultraviolet–visible), XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), FTIR (Fourier transform infrared spectroscopy), etc., and catalytic activity on various hazardous systems.

Metal Oxide/Nitrogen-Doped Carbon Nanosheet Heteronanostructures as Highly Efficient Electromagnetic Wave Absorbing Materials

In this paper, we will discuss the excellent broadband microwave absorption behaviors of Cu/CuO/carbon nanosheet composites: traces of copper and oxide embedded in a carbon nano-sheet not only cut down the high permittivity of adsorbs but also induce more interfacial polarization centers. The results showed that at a cracking temperature of 900 °C, the fabricated material has a unique ripple-like structure, which promotes the hierarchical interfacial polarization. The prepared material has a maximum absorption bandwidth of 4.48 GHz at an exceedingly thin thickness of 1.7 mm and a maximum reflection loss of −25.3 dB at a thickness of 2 mm. It is a relatively ideal material for electromagnetic wave absorption.

Synthesis of carboxylated silicon phthalocyanine photosensitive microspheres with controllable etching

Using a new kind of alkenyl silicon phthalocyanine, styrene (St) and methacrylic acid as monomers and potassium persulfate as an initiator, carboxylated silicon phthalocyanine photosensitive microspheres were synthesized by in-situ emulsion copolymerization. The structure and morphology of the microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR)and scanning electron microscopy. Fluorescence spectrometer was used to characterize the optical property of the microspheres. The experimental results show that silicon phthalocyanine molecules with flexible unsaturated side chains have good compatibility with styrene. With the presence of carboxyl groups, the as-prepared photosensitive microspheres show high monodispersity and stability. On the basis of this, 9,10-diphenylanthracene (DPA) as singlet oxygen indicator was used to evaluate the photosensitivity of the microspheres. In addition, we report a novel phenomenon that the microspheres can be controllable etched by light irradiation with the presence of DPA in a specific solvent.

In situ growth of copper(ii) phthalocyanine-sensitized electrospun CeO2/Bi2MoO6 nanofibers: a highly efficient photoelectrocatalyst towards degradation of tetracycline

Copper(ii) phthalocyanine-sensitized electrospun CeO₂/Bi₂MoO₆ nanofibers (TNCuPc/CeO₂/Bi₂MoO₆ nanofibers) were fabricated and applied as an efficient novel photocatalyst with enhanced photoelectrocatalytic activity.

Photocatalyst with annulated binuclear thioporphyrazine-enhancing photocatalytic performance by expansion of a π-electron system

A novel planar binuclear zinc hexa(2,3-bis(butylthio)) porphyrazine sharing one benzene ring was successfully synthesized, which exhibits superior photocatalytic activity compared to that of its mononuclear counterpart owing to the expansion of the π-electron system.

Highly efficient removal of organic contaminants based on peroxymonosulfate activation by iron phthalocyanine: mechanism and the bicarbonate ion enhancement effect

The development of catalytic oxidation processes with high efficiency based on peroxymonosulfate (PMS) activation is a promising yet challenging research topic in the environmental catalysis field.

Visible/near-IR-light-driven TNFePc/BiOCl organic-inorganic heterostructures with enhanced photocatalytic activity

Although semiconductor photocatalysis has been reported for more than 40 years, the spectral response is still focused on the region of UV-Visible and it is seldom extended to more than 600 nm. In this work, visible/near-IR-light-driven 2,9,16,23-tetranitrophthalocyanine iron (FeTNPc)/bismuth oxychloride (BiOCl) organic-inorganic heterostructures have been synthesized by a two-step solvothermal method. The obtained products were characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron and transmission microscopy, energy dispersive X-ray spectrometer, UV-vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption, and electrochemical measurements. The photocatalytic activity for the decomposition of methyl orange and bisphenol A solution can be significantly improved under visible/near-IR-light irradiation. Through detecting the main oxidative species by trapping experiments, the results show holes and ˙O2(-) radicals are majorly and minorly responsible for photodegradation respectively. What's more, the FeTNPc/BiOCl composite photocatalyst still retained the photocatalytic activity after three cycle measurements.

Fractal and Lacunarity Analyses: Quantitative Characterization of Hierarchical Surface Topographies

Biomimetic hierarchical surface structures that exhibit features having multiple length scales have been used in many technological and engineering applications. Their surface topographies are most commonly analyzed using scanning electron microscopy (SEM), which only allows for qualitative visual assessments. Here we introduce fractal and lacunarity analyses as a method of characterizing the SEM images of hierarchical surface structures in a quantitative manner. Taking femtosecond laser-irradiated metals as an example, our results illustrate that, while the fractal dimension is a poor descriptor of surface complexity, lacunarity analysis can successfully quantify the spatial texture of an SEM image; this, in turn, provides a convenient means of reporting changes in surface topography with respect to changes in processing parameters. Furthermore, lacunarity plots are shown to be sensitive to the different length scales present within a hierarchical structure due to the reversal of lacunarity trends at specific magnifications where new features become resolvable. Finally, we have established a consistent method of detecting pattern sizes in an image from the oscillation of lacunarity plots. Therefore, we promote the adoption of lacunarity analysis as a powerful tool for quantitative characterization of, but not limited to, multi-scale hierarchical surface topographies.

Facile preparation of yolk–shell structured Si/SiC@C@TiO2 nanocomposites as highly efficient photocatalysts for degrading organic dye in wastewater

The prepared yolk–shell Si/SiC@C@TiO₂ nanospheres show a strong photon absorbance throughout the visible light region, and excellent photocatalytic performance for degrading methyl blue in water under UV and visible light irradiation.

Marine sponge skeleton photosensitized by copper phthalocyanine: A catalyst for Rhodamine B degradation

We present a combined approach to photo-assisted degradation processes, in which a catalyst, H2O2 and UV irradiation are used together to enhance the oxidation of Rhodamine B (RB). The heterogeneous photocatalyst was made by the process of adsorption of copper phthalocyanine tetrasulfonic acid (CuPC) onto purified spongin-based Hippospongia communis marine sponge skeleton (HcS). The product obtained, CuPC-HcS, was investigated by a variety of spectroscopic (carbon-13 nuclear magnetic resonance 13C NMR, Fourier transform infrared spectroscopy FTIR, energy-dispersive X-ray spectroscopy EDS) and microscopic techniques (scanning electron microscopy SEM, fluorescent and optical microscopy), as well as thermal analysis. The study confirms the stable combination of the adsorbent and adsorbate. For a 10 mg/L RB solution, the percentage degradation reached 95% using CuPC-HcS as a heterocatalyst. The mechanism of RB removal involves adsorption and photodegradation simultaneously.

Nature-inspired optimization of hierarchical porous media for catalytic and separation processes

Nature-inspired structuring at the meso-scale: broad macropores separate the mesoporous catalyst grains.

One-dimensional Ag3PO4/TiO2 heterostructure with enhanced photocatalytic activity for the degradation of 4-nitrophenol

A one-dimensional Ag₃PO₄/TiO₂ heterostructure exhibits enhanced photocatalytic activity due to the good visible light absorption capability and excellent charge separation characteristics of the formed heterojunction.

ZnO nanorod/nickel phthalocyanine hierarchical hetero-nanostructures with superior visible light photocatalytic properties assisted by H2O2

ZnO-NR/TPNiPc hierarchical hetero-nanostructure arrays exhibited superior visible light photocatalytic activities in degradation of Rhodamine B assisted by H₂O₂.

Novel catalyst of zinc tetraamino-phthalocyanine supported by multi-walled carbon nanotubes with enhanced visible-light photocatalytic activity

Zinc tetraamino-phthalocyanine (ZnTAPc) supported by multi-walled carbon nanotubes (MWCNTs) hybrid materials were successfully fabricated by the method of chemical grafting and their photocatalysis behavior was reported.

Synthesis, characterization and photocatalytic activity of new photocatalyst ZnBiSbO4 under visible light irradiation

In this paper, ZnBiSbO₄ was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO₄ had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO₄ crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO₄ was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO₄ as a catalyst compared with nitrogen-doped TiO₂ (N-TiO₂) and CdBiYO₄. The results showed that ZnBiSbO₄ owned higher photocatalytic activity compared with N-TiO₂ or CdBiYO₄ for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO₄²⁻ and NO₃⁻, and the evolution of CO₂ revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth.

Catalytic Activity of Tetranitro-Copper Phthalocyanine Supported on Carbon Nanotubes towards Oxygen Reduction Reaction

Acid-functionalized multiwalled carbon nanotube (AF-MWCNT)-supported tetranitro-copper phthalocyanine (TNCuPc) assemblies were prepared by solid phase synthesis method. The products were characterized by infrared spectroscopy, scanning electron microscopy and XRD. The electrocatalytic activity of the obtained AF-MWCNT-supported TNCuPc assemblies was measured by cyclic voltammetry (CV) and rotating disk electrode (RDE) techniques in an oxygen-saturated 0.1 M KOH. The results showed that the catalytic activity of TNCuPc/AF-MWCNTs towards oxygen reduction was a two-step, two-electron process for oxygen reduction.

Carbon-modified BiVO4 microtubes embedded with Ag nanoparticles have high photocatalytic activity under visible light

Carbon-modified BiVO(4) microtubes embedded with Ag nanoparticles (BVO@C/Ag MTs) were obtained by a two-step fabrication route. First, the BiVO(4)@carbon core-shell microtubes (BVO@C MTs) were fabricated by using BiVO(4) microtubes (BiVO(4) MTs) as a hard-template through a hydrothermal approach. Next, small Ag nanoparticles (Ag NPs) with well-dispersed distribution were assembled inside the carbon layer of the BVO@C MTs via an in situ reduction method. The results showed that small Ag NPs were well dispersed inside the carbon layer of approximately 8 nm in thickness around the BiVO(4) microtubes. The photocatalytic studies revealed that the BVO@C/Ag MTs exhibited the highest photocatalytic activity for photodegradation of rhodamine B (RB) compared to the pure BVO-MTs, BVO@C MTs under visible light irradiation. The high separation efficiency of photogenerated electron-hole pairs based on the photosynergistic effect among the three components of BiVO(4), carbon, and Ag and the improved visible light utilization from the sensitizing effects of carbon layers both contribute to the enhanced photocatalytic activity. The BVO@C/Ag MTs did not exhibit any significant loss of activity after three cycles of RB photodegradation, which results from the fact that the presence of the carbon layer could inhibit loss and oxidation of Ag NPs during repeated applications. The BVO@C/Ag MTs could be easily recovered by sedimentation due to their one-dimensional nanostructural property.