Photocatalytic Degradation Of Pollutants Research Articles

Composite Membrane of Bi<sub>2</sub>WO<sub>6</sub>-NCQDs Laminated Hetero-junction Loaded on PES Support for Photo-catalytic Degradation of Organic Pollutants

Composite Membrane of Bi<sub>2</sub>WO<sub>6</sub>-NCQDs Laminated Hetero-junction Loaded on PES Support for Photo-catalytic Degradation of Organic Pollutants

Terpyridine-based metallo-cuboctahedron nanomaterials for efficient photocatalytic degradation of persistent organic pollutants

Terpyridine-based metallo-cuboctahedron nanomaterials for efficient photocatalytic degradation of persistent organic pollutants

Rationally designed β-FeOOH/N,P-MXene Schottky-junction for efficient removal of pollutants from wastewater

Effective separation of photogenerated electrons and holes, as well as providing ample reactive sites, is crucial for enhancing the activity of photocatalytic degradation of pollutants in water. In this study, we have expanded MXene through a simple water swelling method and successfully doped N and P elements into MXene via a hydrothermal process. This modification not only exfoliates the layered structure of MXene, enlarging its specific surface area and providing abundant reactive sites but also endows MXene with enhanced metallic properties. As a result, an N,P-MXene/FeOOH Schottky junction photocatalyst is constructed. Our photocatalytic experiments revealed that the FO-NPM200/H2O2 system performs well under extreme pH conditions and exhibits excellent photocatalytic stability across a wide pH range (1–13), suggesting its outstanding potential for practical applications in complex environments. Under conditions of pH = 7 without the presence of inorganic salt ions, the degradation rate of tetracycline reached 98.1 %, and the photocatalytic reduction rate of the common heavy metal salt Cr(VI) was as high as 99.4 %. We have also unveiled the band structure of FO-NPM200 using UPS and UV–vis DRS. This research paves a new way for the design and construction of Schottky junction photocatalysts.

Green synthesis of nano-MgO using lemon juice for amplified photocatalytic degradation of organic pollutants

This study examines the photocatalytic activity of the green synthesized (using lemon juice) MgO nanoparticles under a halogen light for the degradation of Congo Red (CR). The characterization of the prepared sample was studied by applying Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA). By applying XRD analysis, the crystallographic variables of the MgO NPs were determined and the crystallite size was obtained from a variety of formulas/models (Scherrer equation, Williamson-Hall model, Monshi-Scherrer model, Size-Strain Plot, Halder-Wagner model, etc). The crystallite size was found in a valid range of 4.62–99.03 nm. Photocatalytic degradation of Congo Red (CR) has been made under halogen light by considering a dye concentration of 20 ppm at 40 mL solution for 0.05 g of the catalyst sample. Operating conditions were fixed as neutral pH, 25 °C temperature, and 40 min exposure time of the halogen lamp.

A Tight-Connection g-C3N4/BiOBr (001) S-Scheme Heterojunction Photocatalyst for Boosting Photocatalytic Degradation of Organic Pollutants.

The efficient separation of photogenerated charge carriers and strong oxidizing properties can improve photocatalytic performance. Here, we combine the construction of a tightly connected S-scheme heterojunction with the exposure of an active crystal plane to prepare g-C3N4/BiOBr for the degradation of high-concentration organic pollutants. This strategy effectively improves the separation efficiency of photogenerated carriers and the number of active sites. Notably, the synthesized g-C3N4/BiOBr displays excellent photocatalytic degradation activity towards various organic pollutants, including methylene blue (MB, 90.8%), congo red (CR, 99.2%), and tetracycline (TC, 89%). Furthermore, the photocatalytic degradation performance of g-C3N4/BiOBr for MB maintains 80% efficiency under natural water quality (tap water, lake water, river water), and a wide pH range (pH = 4-10). Its excellent photocatalytic activity is attributed to the tight connection between g-C3N4 and BiOBr in the S-scheme heterojunction interface, as well as the exposure of highly active (001) crystal planes. These improve the efficiency of the separation of photogenerated carriers, and maintain their strong oxidation capability. This work presents a simple approach to improving the separation of electrons and holes by tightly combining two components within a heterojunction.

A facile green synthesis of gold nanoparticles using Canthium parviflorum extract sustainable and energy efficient photocatalytic degradation of organic pollutants for environmental remediation

Organic dye and nitrophenol pollution from textiles and other industries present a substantial risk to people and aquatic life. One of the most essential remediation techniques is photocatalysis, which uses the strength of visible light to decolorize water. The present study reports Canthium Parviflorum (CNP) leaf extract utilization as an effective bio-reductant for green synthesis of Au NPs. A simple, eco-friendly process with low reaction time and temperature was adopted to synthesize CNP extract-mediated Au-NPs (CNP-AuNPs). The prepared AuNPs characterization involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS) surface area analysis, ultraviolet–visible spectroscopy (UV–Vis). XRD results showed that the cubic-structured AuNPs had a crystallite size of 14.12 nm. Assessment of organic dyes performance in degrading brilliant green (BTG) and amido black 10B (AMB) under visible light irradiation highlights an impressive 83.25% and 86% degradation efficiency within 120 min, accompanied by a kinetic rate constant dyes was found to be 0.0828 min⁻1, BTG, and 0.0123 min⁻1, Furthermore, the reduction of 4-nitrophenol by NaBH4 using CNP-AuNPs as a catalyst demonstrated good catalytic performance and rapid degradation at 89.4%. and rate constant 0.099 min−1 followed pseudo-first-order. The LC-MS analysis identified various intermediates during the degradation of the CR dye. Radical trapping experiments suggest that photogenerated free electrons and hydroxyl radicals are crucial for degrading the amido black 10B dye The AuNPs influenced the significant factors responsible for the photocatalytic activity, such as the increase in range of absorbance, increased e− and h+ pair separation, improvement in the charge transfer process, and active site formation, which significantly enhanced the process of degradation. We found that the CNP-AuNPs could effectively remove dyes and nitrophenol from industrial wastewater.

Tailoring CuOx loading on CoFe2O4 nanocubes photocatalyst for superior photocatalytic degradation of triclosan pollutants under VL irradiation and toxicological evaluation

In this study, we report the development of a novel CuOx(3 wt%)/CoFe2O4 nanocubes (NCs) photocatalyst through simple co-precipitation and wet impregnation methods for the efficient photocatalytic degradation of triclosan (TCS) pollutants. Initially, rod-shaped bare CoFe2O4 was synthesized using a simple co-precipitation technique. Subsequently, CuOx was loaded in various percentages (1, 2, and 3 wt%) onto the surface of bare CoFe2O4 nanorods (NRs) via the wet impregnation method. The synthesized materials were systematically characterized to evaluate their composition, structural and electrical characteristics. The CuOx(3 wt%)/CoFe2O4 NCs photocatalyst exhibited superior photocatalytic degradation efficiency of TCS (89.9%) compared to bare CoFe2O4 NRs (62.1 %), CuOx(1 wt%)/CoFe2O4 (80.1 %), CuOx(2 wt%)/CoFe2O4 (87.0 %) under visible light (VL) irradiation (λ ≥ 420 nm), respectively. This enhanced performance was attributed to the improved separation effectiveness of photogenerated electron (e−) and hole (h+) in CuOx(3 wt%)/CoFe2O4 NCs. Furthermore, the optimized CuOx(3 wt%)/CoFe2O4 NCs exhibited strong stability and reusability in TCS degradation, as demonstrated by three successive cycles. Genetic screening on Caenorhabditis elegans showed that CuOx(3 wt%)/CoFe2O4 NCs reduced ROS-induced oxidative stress during TCS photocatalytic degradation. ROS levels decreased at 30, 60, and 120-min intervals during TCS degradation, accompanied by improved egg hatching rates. Additionally, expression levels of stress-responsible antioxidant proteins like SOD-3GFP and HSP-16.2GFP were significantly normalized. This study demonstrates the efficiency of CuOx(3 wt%)/CoFe2O4 NCs in degrading TCS pollutants, offers insights into toxicity dynamics, and recommends its use for future environmental remediation.

Radiant synergy: Illuminating methyl orange dye removal with g-C3N4/ZnO heterojunction photocatalyst

In this study, a robust hybrid heterojunction composite of g-C3N4/ZnO was successfully synthesized using a straightforward and cost-effective coprecipitation method. The resulting composite amalgamates the properties of graphitic carbon nitride (g-C3N4) and zinc oxide nanoparticles (ZnO NPs). Thorough characterization using techniques such as XRD, FT-IR, FE-SEM, HR-TEM, UV-DRS, EIS, PL, and EDX confirmed the structural and elemental composition of the catalyst. The challenge of using photons as the sole energy source for the activation of photocatalysts under ambient conditions was addressed. The photocatalytic potential of the hybrid heterojunctions was assessed by degrading the methyl orange (MO) dye under sunlight. The 10 wt% g-C3N4/ZnO composite exhibited effective suppression of charge recombination during photocatalytic degradation. Notably, the heterojunction 10 wt% g-C3N4/ZnO composite displayed remarkable photocatalytic performance, achieving a substantial 98 % degradation of MO within 90 min of solar irradiation, outperforming other materials. Moreover, the synthesized composites exhibited favorable attributes in terms of recyclability and mechanical stability, retaining their efficacy over five cycles. This substantiates their promising role as potential candidates for future photocatalyst applications. In essence, g-C3N4/ZnO heterojunction composites offer a robust solution for efficient and sustainable photocatalytic degradation of organic pollutants.

One-pot anchoring BaBi2O6/Bi2O3 nanoparticles on oxygen vacancy rich TiO2: Double Z-scheme nanocomposites with QDs size for elimination of wastewater pollutants

The emergence of nanostructured photocatalysts with high activity offers facile solutions for removing water pollutants. In this study, a novel double Z-scheme TiO2-x/BaBi2O6/Bi2O3 nanocomposite with QDs size of about 5.52 nm was prepared by a facile one-pot hydrothermal procedure, and its activity was studied in the photocatalytic degradation of pharmaceutical and dye pollutants. The optimized nanocomposite showed a significant efficiency in the removal of tetracycline, rhodamine B, fuchsine, methylene blue, and chromium (IV), which was 12.4, 7.38, 11.1, 10.2, and 12.1 times higher than pure TiO2-x, respectively. The presence of oxygen deficiency in the crystal lattice of TiO2-x/BaBi2O6/Bi2O3 nanocomposite played a significant role in the effectual separation of photoexcited charges, increasing reactive active sites, and capturing charge carriers. Besides, providing a short distance for the rapid migration of charges to the surface of the nanocomposite was possible with the quantum size of the catalyst particles. Enforced by the established double Z-scheme heterojunctions, the charge segregation was considerably enhanced along with maintaining their redox capability. Finally, biocompatibility tests showed the harmlessness of the treated solution for agricultural use.

Construction of oxygen-doped g-C3N4/BiOCl (S-scheme) heterojunction: Efficient degradation of tetracycline in wastewater

Graphitic phase carbon nitride (g-C3N4) demonstrates significant promise in the photocatalytic degradation of organic pollutants, but the rapid recombination of photogenerated electron-hole pairs seriously restricts its degradation capacity. In this study, an innovative heterostructural anion regulation strategy based on g-C3N4 was proposed to significantly enhance the degradation performance of tetracycline. Initially, we regulated the electron configuration of g-C3N4 through O doping to optimize the active sites at the reaction interface. Subsequently, the S-scheme heterojunction was constructed by introducing BiOCl to stimulate the pumping effect and form efficient build-in electric field electron channels. The oxygen-doped g-C3N4/BiOCl (OCN/BiOCl) heterojunction material obtained through aforementioned modification exhibited a degradation efficiency of 89.33 % towards 20 mg·L−1 tetracycline (90 min light reaction, 30 min dark reaction), which was 2.5 times that of conventional g-C3N4 catalyst. In particular, density functional theory calculations and ultraviolet photoelectron spectroscopy jointly revealed the unique chemical environment and electronic structure between OCN and BiOCl due to the formation of the build-in electric field, thereby providing enhanced pathways for the migration of photogenerated currents. Meanwhile, the heterostructure significantly reduced the transport distance of photo-induced charge and minimizes the internal transmission resistance. It enhances the efficiency of separating photogenerated electrons and hole pairs, which is the key mechanism for greatly improving the photocatalytic degradation performance of OCN/BiOCl materials. In summary, the hetero-anion regulation strategy proposed in this study addresses the issue of rapid recombination of photogenerated charges in g-C3N4, providing a new perspective for efficient control of organic pollutants in the environment driven by g-C3N4 photocatalyst.

Cyano-deficient g-C3N4 for round-the-clock photocatalytic degradation of tetracycline: Mechanism and application prospect evaluation

Without light at night, the system for photocatalytic degradation of refractory organic pollutants in aquatic environments based on free radicals will fall into a dormant state. Hence, a round-the-clock photocatalyst (CCN@SMSED) was prepared by in situ growth of cyanide-deficient g-C3N4 on the surface of Sr2MgSi2O7:Eu2+,Dy3+ through a simple calcination method. The CCN@SMSED exhibits an outstanding oxidative degradation ability for refractory tetracycline (TC) in water under both light and dark conditions, which is attributed to the synergistic effect of free radical (•O2− and •OH) and non-radical (h+ and 1O2). Electrochemical analyses further indicate that direct electron transfer (DET) is also one of the reasons for the efficient degradation of TC. Remarkably, the continuous working time of the round-the-clock photocatalyst in a dark environment was estimated for the first time (about 2.5 h in this system). The degradation pathways of TC mainly include demethylation, ring opening, deamination and dehydration, and the growth of Staphylococcus aureus shows that the process is biosafe. More importantly, CCN@SMSED holds significant promise for practical application due to its low energy consumption and suitability for removing TC from a variety of complex water bodies. This work provides an energy consumption reference for the practical application of round-the-clock photocatalytic degradation of organic pollutants.

Photothermal-assisted photocatalytic degradation of tetracycline in simulated natural water by BiVO4/CuBi2O4 Z-scheme heterojunction: Mechanisms insight, degradation pathways and toxicity assessment

The photothermal effect generated under illumination can increase the surface temperature of the catalyst, and enhance the migration rate of the photogenerated carrier and the activity of the catalytic reaction, which is an effective way to promote photocatalytic degradation of pollutants. In this study, a Z-scheme BiVO4/CuBi2O4 (BVO-CBO) heterojunction with 0D/1D structure was prepared by hydrothermal method. Compared with pure BVO and CBO, the temperature of the Z-scheme BVO-CBO heterojunction can reach 90.1°C after 180 S illumination, and the temperature of the BVO-CBO+TC solution system can rise to 39.5°C after 10 min, which has higher heating rate and photocatalytic performance than the monomer catalyst. The experimental results showed that the photogenerated electron transfer pathway combined with the photothermal effect effectively promoted the separation of photogenerated carriers and maintained a strong redox potential, so that the removal rate of tetracycline (TC) by BVO-CBO reached 85.0 % within 90 minutes, which was significantly higher than that of pure BVO (39 %) and CBO (33 %). In addition, the toxicity of intermediate products gradually decreased during TC degradation. In addition, the effects of reaction temperature, pH, concentration of TC, common aquatic substrates and simulated natural water on TC removal were also studied. The combination of its structural advantages, redox capabilities, and photothermal effect provided a promising approach to the treatment of antibiotic-contaminated water.

Graphene Oxide as Novel Visible Light Active Photocatalyst: Synthesis, Modification by Nitrogen and Boron Doping, and Photocatalytic Application

Graphene oxide (GO) has become one of the emerging and important sole photocatalyst nanomaterials in recent years due to its exceptional/tunable optoelectronic properties, multifunctionality, and eco‐friendly nature. However, challenges remain in tuning surface chemistry, tailoring the band gap, developing doping strategies, and understanding the sole photocatalytic mechanism. This contribution investigated the synthesis of GO via the improved Hummers method by varying the ratio of the oxidizing agents (K2Cr2O7:KMnO4), as well as modifications by nitrogen (N) and boron (B) doping in view of its applications in photocatalytic degradation of organic dye pollutants. Furthermore, changes in surface chemistry, optical, compositional, morphological, and structural properties are investigated to understand the photocatalytic mechanism. The synthesized GO showed a broad spectrum of light absorption with a tunable band gap of 2.4–4.3 eV and exhibited more than 91% degradation of methylene blue dye under direct sunlight. However, the photocatalytic activity decreased after N and B doping attributed to reduced oxygen‐containing functional groups, low surface area, and dopants‐induced bonding configurations within the GO structure. This study provides a new insight into replacing metallic semiconductor photocatalysts with highly affordable, environmentally friendly, and potent metal‐free GO photocatalysts.

PVA hydrogel serve as a high-efficiency carrier to enhance the photocatalytic degradation performance of BiOBr

BiOBr is a bismuth-containing photocatalytic material that exhibits visible light activity, making it highly promising for applications in photocatalytic degradation of pollutants and ecological protection. However, its application is hinder by the powder form and small particle size. Loading a powder photocatalyst on a suitable carrier is a common way to solve this challenge. This study proposes that PVA hydrogel can be used as a highly efficient carrier to enhance the photocatalytic degradation performance of BiOBr. By adding a foaming agent, the pore structure of hydrogel was improved and the degradation performance to pollutants in wastewater was increased. The impact of various factors, including BiOBr photocatalyst loading, solution pH, recycling stability, and reactive species, on the photocatalytic degradation process were investigated. The performance of the PVA/BiOBr composite hydrogel to degrade methylene blue (MB) under simulated solar irradiation was studied. After a 120 min photocatalytic reaction, PVA/BiOBr-1.0 % composite hydrogel removed 99 % of 10 mg·L−1 MB, which was superior to pure BiOBr photocatalyst. This investigation is of significance as it provides insights into the integration of BiOBr catalysts key role of the PVA hydrogel carriers in enhancing the catalytic performance of BiOBr photocatalyst in wastewater treatment.

Recent advances in photocatalytic removal of antiviral drugs by Z-scheme and S-scheme heterojunction.

The possible impact of antivirals on ecosystems and the emergence of antiviral resistance are the reasons for concern about their environmental release. Consequently, there has been a significant increase in curiosity regarding their presence in both organic and synthetic systems in recent years. The primary objective of this review is to address the void of information regarding the global presence of antiviral drugs in both wastewater and natural water sources. Photocatalytic degradation of pollutants is an eco-friendly, cost-effective method that effectively addresses environmental degradation. The development of efficient photocatalysts remains a significant issue in accelerating the degradation of pollutants, especially when employing solar light. Thus, the development of Z-scheme and S-scheme semiconductor heterojunctions has emerged as a viable method to improve light absorption and enhance the redox capability of photocatalysts. The principles of Z-scheme and S-scheme are reviewed extensively. The degradation route and occurrence of antiviral are discussed briefly. Finally, a short preview of the degradation of antiviral using Z-scheme and S-scheme is also highlighted.

Synthesis and characterization of pristine CuO and Mg/CuO nanostructures for their anti-breast cancer and photocatalytic degradation applications: Experimental and DFT investigations

The present manuscript emphasizes the versatility of Mg-doped CuO nanostructures for environmental remediation (photocatalytic degradation of pollutants) and biomedical applications (anticancer activity) thus highlighting their potential impact in addressing societal and health challenges. The primary focus of the manuscript is the synthesis, characterization, and applications of Mg-doped CuO nanostructures. In order to meet this purpose, pure and Mg doped CuO nanostructures were synthesized using the solid-state reaction method and ball milling techniques. To characterize the prepared samples, X-ray diffraction, transmission electron microscopy, UV-Visible, photoluminescence, and Raman spectroscopy techniques were utilized. A profusion of structural defects and the reduction in crystallite size have been observed in CuO nanomaterial’s due to the dopant's complete incorporation into the CuO lattice. Additionally, the band gap of CuO has been observed to decrease as a result of Mg doping. Density functional theory was employed to simulate the effect of Mg on the properties of CuO. The efficiency of photocatalytic degradation aided by sunlight against methylene blue increased from 50.8 % to 89.5 %. MCF-7, a cell line representing human breast adenocarcinoma, was utilized to assess the cytotoxicity of Mg/CuO samples. CuO nanoparticles enriched with Mg are viable biocompatible anti-cancer agents and prospective photocatalyst for the removal of environmental pollutants from aqueous solutions, according to the findings of this study.

Interaction of phenolic compounds with functionalized TiO2: Enhanced catechol adsorption and cooperative phenol adsorption

A commercial TiO2 sample functionalized with 3-aminopropyltrimethoxysilane (APTMS) and 4-carboxyphenylboronic acid (CPBA), has been previously proposed as a suitable photocatalyst to perform selective photocatalytic degradation of pollutants in aqueous streams, while avoiding the oxidation of valuable catechol simultaneously present in the reacting medium. In the present study, we highlight the adsorption mechanisms underlying the higher affinity of catechol, compared to phenol, with the surface of modified TiO2, quantitatively justifying the photocatalytic selective degradation results previously obtained. Moreover, a cooperative adsorption mechanism of phenol onto the TiO2 sample modified with APTMS has been for the first time observed. The resulting sigmoidal adsorption isotherms, satisfactorily fitted with the Hill model, could be attributed to the enhanced surface hydrophobicity and, more importantly, to alterations of the folding of APTMS molecules on the TiO2 surface occurring upon increasing the concentration of the phenolic compounds.Photocatalytic tests revealed that the existence of boronate groups on the surface of TiO2 hinders the photocatalytic degradation of catechol and facilitates a swifter oxidation of phenol. These findings confirm the potential for selective photocatalytic degradation, in line with modern conceptions of innovative and environmentally sustainable wastewater treatments.

In situ-growth of Fe2S3 ultrathin layer on CdS nanorod through cation-exchange for efficient photocatalytic degradation of organic pollutants under visible light coupled oxidant activation

A new core-shell structure CdS@Fe2S3 material was synthesized by in situ cation exchange method to enhance the degradation of organic pollutants in water under visible light. It is proved that Fe2S3 nanolayer is successfully loaded on CdS nanorods by TEM and UV-Vis spectra and other means. The representative Rhodamine B was selected as the target pollutant and the results of degradation experiment showed that after 60 min of exposure to LED visible light with a low energy (25 W), the removal efficiency for this dye could reach 98 % in the presence of peroxymonosulfate (PMS) forming free radicals, which displayed a observed kinetic rate constant exceeding 0.62 min−1 that is approximately 5 times higher than the system without PMS addition and 10 times than the system with original CdS as catalyst. The result of inhibition experiments shows that sulfate radical (SO4·-) and singlet oxygen (1O2) play as important roles during the photocatalytic process. In addition, this core-shell material can be recycled at least four times. Generally, this study can make full use of visible light which can be easily obtained and effectually resolve the organic pollution problems.

Rational Design of Z-Scheme Heterostructures Composed of Bi/Fe-Based MOFs for the Efficient Photocatalytic Degradation of Organic Pollutants

Rational Design of Z-Scheme Heterostructures Composed of Bi/Fe-Based MOFs for the Efficient Photocatalytic Degradation of Organic Pollutants

Magnetically separable and recyclable ZnFe2O4 nanoparticles as an effective activator in resorcinol-formaldehyde resins-based photocatalysis-self-Fenton system

Non-homogeneous photocatalysis-self-Fenton technology presents an effective strategy for efficient photocatalytic degradation of pollutants, circumventing the issues of extensive contamination of water resources by free iron ions and reducing safety risks and cost issues associated with the generation of hydrogen peroxide (H2O2). In the photocatalysis-self-Fenton reaction, the activation efficiency of H2O2 determines the capacity for photocatalytic degradation and mineralization of pollutants. Consequently, this study adopted ZnFe2O4 (ZFO) as an efficient, magnetically recoverable H2O2 activator, successfully coupling it with resorcinol–formaldehyde (RF) resin to construct a photocatalysis-self-Fenton system, thereby achieving degradation of tetracycline (TC) under visible light. The experimental results revealed that apparent rate constant (kapp) for the RF/ZFO photocatalysis-self-Fenton system is 22.997 times higher than that of the Fenton system and 1.156 times higher than that of the photo-Fenton system. Under visible light, the RF resin can generate H2O2 in situ and is subsequently activated by ZFO, resulting in a highly oxidized hydroxyl radical (OH), attacking contaminants. This study presents new insights into the construction of efficient heterogeneous radiofrequency resin photocatalysis-self-Fenton degradation system and provides new solutions for efficient and environmentally friendly wastewater treatment.