Photodegradation Of Pollutants Research Articles

Magnetically separable Cu-Fe nanophotocatalyst with enhanced photocatalytic performance under visible-light irradiation: Optimizing the fuel type and heating approach in the synthesis process

This study aimed to examine the influence of fuel type and heating technique on the solution one-step solution combustion synthesis of CuFe2O4 spinel-type photocatalysts. The primary goal was to establish the best configuration of nanophotocatalysts with desirable characteristics, leading to improved photodegradation of dye pollutants when exposed to simulated solar radiation. Cu-spinel nanophotocatalysts were generated using a one-step combustion method involving three distinct fuels (urea, glycine, and citric acid) and two heating strategies (microwave and muffle furnace). The synthesized nanophotocatalysts were characterized through a range of tests, including XRD, FESEM, EDX, BET-BJH, FTIR, VSM, PL, DRS, and pHpzc analyses. During the simulated irradiation of sunlight, the efficacy of the Cu-spinel photocatalyst was evaluated using high-concentration Congo red, a widely used textile dye. Test results indicate that the Cu-spinel nanophotocatalyst formed utilizing glycine and microwave combustion displayed a desirable photocatalytic activity by degradation of 97 % of Congo red in 100 min. In addition, the photocatalytic efficiency of Congo red degradation was significantly enhanced compared to the other fuels and the conventional heating approach. Furthermore, CuFe(G-MW) demonstrated high stability throughout four cycles. Finally, a proposed mechanism for the degradation of Congo red using a CuFe(G-MW) nanophotocatalyst was presented.

Green synthesis of CuO/Fe2O3/ZnO ternary composite photocatalyst using grape extract for enhanced photodegradation of environmental organic pollutant

This research delves into fabricating a CuO/Fe2O3/ZnO (CFZ) ternary composite photocatalyst, employing grape extract for its eco-conscious synthesis. The method intricately integrates copper acetate, ferric nitrate, and zinc acetate as precursor compounds, harmonizing them with grape extract serving as a green reducing agent. Meticulous microwave treatment and controlled calcination orchestrate the nuanced formation of the desired composite material. The extensive characterization, involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) spectroscopy, unveils an array of favorable physical, chemical, and optical attributes conducive to proficient photocatalysis. Notably, CFZ–10mc showcases a narrower bandgap of 1.91 eV, which is pivotal for bolstering electron–hole separation, thereby enhancing its photocatalytic efficacy. Assessment of CFZ's performance in degrading Rhodamine B (RhB) under UV irradiation highlights an impressive 88.8% degradation efficiency within 120 min, accompanied by a kinetic rate constant of 1.81 × 10−2 min−1. Deliberation upon crucial parameters, including photocatalyst dosage, initial RhB pH, and reactor energy consumption, introduces the electrical energy per order (EEO) as a notable efficiency metric. CFZ manifests a substantial reduction in operational costs, estimated to be 18.10 times lower than conventional photolysis, signifying an EEO value of 509.17 kWh m−3 order−1. Optimal operational conditions propose a photocatalyst content of 1.5 g L−1 and an initial RhB pH of 7, fostering the prevalence of the primary active species, •OH. These findings illuminate CFZ's potential in mitigating organic pollutants, underlining its pivotal role in sustainable water remediation. Additionally, practical implementation guidelines for leveraging CFZ's capabilities in real-world applications are presented with care and consideration.

Enhanced sunlight-driven photocatalysis owing to synergetic effect of gold nanoparticles-incorporated ZnO/rGO ternary heterostructures

The combination of gold nanoparticles (Au NPs) incorporated ZnO/rGO heterostructures is unique for sunlight-driven photocatalysis (SPC). Here, hydrothermally synthesized pristine ZnO nanostructures (NSs), ZnO/rGO binary nanocomposites (BNCs) and ZnO/rGO/Au ternary nanocomposites (TNCs) of bandgap (Eg) values 3.56 eV, 3.37 eV and 3.17 eV, respectively are reported. These NSs are analyzed optically, structurally and morphologically via UV–Vis absorption spectroscopy, X-ray diffraction and SEM techniques, respectively. The SPC of methylene blue (MB) organic dye was considered using all three samples. The slow charge transfer over grain boundaries of ZnO results in the prohibition of photogenerated electron-hole pairs, exhibiting low photodegradation efficiency (87%). However, in BNCs the creation of alternative pathway of the carriers due to low work function level of rGO as compared to ZnO enhances the charge separation with an increased photocatalytic efficiency (92%). In contrast, TNCs show rather fast photodegradation efficiency (96%) as the photoexcited electrons on Au NPs surface migrate to the CB of ZnO because of the SPR stimulation of Au. These electrons easily shift to the conductive rGO layers and react with oxygen species (O2) producing superoxide radicals (•O2–). Thus, TNCs sample has appeared to be auspicious candidate for the photodegradation of organic pollutants in untreated water.

Eu2CuO4 nanostructures: A simple co-precipitation pathway, characterization, and promising photocatalytic application for dye removal under visible light

Contamination of water has become an international concern, and finding efficient and sustainable methods to eliminate harmful pollutants is crucial for ensuring that clean and safe water resources are available. A promising approach in this regard is photocatalysis, which uses light energy to initiate chemical reactions that break down organic contaminants into harmless byproducts. This study presents a nanophotocatalyst based on europium copper oxide (Eu2CuO4) for the elimination of hazardous pollutants. The fabrication of Eu2CuO4 nanostructures was achieved through a simple and rapid co-precipitation process. According to diffuse reflectance spectroscopy (DRS), Eu2CuO4 has an optical bandgap of 1.56 eV, making it suitable for use in visible light. A variety of techniques were used to characterize Eu2CuO4 nanostructures, including XRD, FESEM, FTIR, VSM, HRTEM, BET, EDS, and LC-MS. In order to maximize effectiveness, several variables were considered, such as the amount of Eu2CuO4 used, the concentration of toxic pollutants, and the pH of the solution. It was found that Eu2CuO4 was quite effective in degrading various organic pollutants, particularly methyl orange (MO) of water. Using 50 mg of Eu2CuO4 in the presence of 20 ppm MO and exposing it to visible radiation for 100 min resulted in 94.9 % of MO being destroyed. A further analysis revealed that hydroxyl radicals (•OH) and holes (h+) played a dominant role in pollutant photodegradation. In light of this finding, Eu2CuO4 may serve as a valuable candidate for developing new materials that are capable of successfully removing contaminants from water.

Synthesis of selenium and fluorine co-doped graphitic carbon nitride for photodegradation of toxic organic pollutants and hydrogen peroxide photoproduction

Science is developing every day to race against the factual growth of industrial pollution in order to redeem the environment. In this study, modification of graphitic carbon nitride via selenium and fluoride doping was successfully conducted. Specifically, the process of co-calcination was conscripted using organic precursors, whilst the foreign elements were obtained from ammonium fluoride and selenium dioxide. The morphological assessment revealed the treated-graphitic carbon nitride possessed a flaky sheet form with high porosity and great crystalline uniformity. Photochemical investigation showed the co-doping of selenium and fluorine elevated the optical properties, including the decrement of bandgap and diminishing the recombination rate of electrons and holes. With interesting improvement in photocatalytic activity, the material was applied in persistent organic compound degradation and hydrogen peroxide production. The treatment improved the degradation percentage, in which the methylene blue removal achieved 99.96 % while the tetracycline removal reached 86.38 %. Moreover, high compatibility and great reusability over 4 cycles were also recorded. When applying the material for the generation of hydrogen peroxide, the co-doped material performance was observed to reach 3307 μM/g.h. The results concluded the advancement in material modification with great application in various aspects.

Fabrication of the ternary dual S-scheme ZnO/ZnS/In2S3 heterojunction for enhancing pollutant photodegradation

The construction of heterojunction for photocatalysis has garnered much research interest. Herein, we report the successful fabrication of a ternary dual S-scheme ZnO/ZnS/In2S3 heterojunction with a higher photocatalytic capacity via a hydrothermal method. Specifically, the optimized ternary heterojunction ZSI0.35 sample achieves the 100 % photodegradation efficiency of RhB (10 mg/L, 50 mL) within 10 min, approximately 17 and 8 times higher than pure ZnO and ZnO/ZnS binary heterojunction, respectively. Further characterization results confirm the dual S-scheme heterojunction structure in the fabricated ZnO/ZnS/In2S3 ternary heterojunction, and the improvement of photocatalytic properties can be attributed to the enhanced Brunauer Emmett-Teller (BET) surface area, the improved redox capacity of the photocatalyst, and the quick charge transfer. Additionally, the possible photocatalytic mechanism is discussed according to the measurements. This work provides an efficient strategy of promising heterojunction photocatalysts for photocatalytic environmental remediation.

Red mud accommodated mesoporous black TiO2 framework with enhanced organic pollutant photodegradation.

In this work, black TiO2 (BTiO2) loaded on black red mud (BRM) was successfully prepared with the conversion of Fe2O3 into magnetic Fe3O4 in red mud and the reduction of partial Ti4+ to Ti3+ in TiO2 via the facile sol-gel method and H2 reduction treatment. The obtained low-cost BRM/BTiO2 composites exhibit remarkable photocatalytic degradation toward rhodamine B (91.2%) and tetracycline (83.6%) under visible light irradiation, much better than pristine TiO2. This enhancement is attributed to the narrow bandgap with the desired solar-light excitation, the black color with good solar-light absorption, and the heterojunctions with the efficient separation of photogenerated electron-hole pairs. Moreover, the desired magnetic separation of BRM/BTiO2 composites realizes the recycle and recovery of photocatalysts, favoring practical applications in environment. This work provides a cost-efficiency way to prepare RM-supported TiO2 composites for treating organic pollutants in the wastewater, which is of great significance to the comprehensive utilization of RM waste, the cost saving of the photocatalyst, and the visible-light active enhancement of TiO2.

Uncovering the potential of yttrium doped zinc oxide nanoparticles as an efficient catalyst for photodegradation of recalcitrant pollutant and a contributor antibacterial property

This work focused on the development of photocatalytic and antibacterial ZnO doped nanoparticles for wastewater treatment application. ZnO nanoparticle was successfully doped via a sol-gel method with different concentration of yttrium (Y), a rare-earth element. The improved properties of the structural, optical, photocatalytic and antibacterial after the nanoparticles doping modification were analyzed. XRD analysis confirmed the hexagonal (wurtzite) structure with average crystalline size between 10 and 22.7 nm. The exhibited XRD peaks that shifted towards lower angles after doping confirmed the Y3+ substitution in the ZnO structures. High-resolution transmission electron microscopy (HRTEM) showed an increase in grain size as the concentration of Y3+ ions inside the ZnO matrix increased. Ultraviolet-visible-near-infrared spectroscopic measurement revealed a red shift of the bandgap energy of 0.128 eV, which confirmed the substitution process. It was observed that the Y-dopant significantly improved the photocatalytic activity of the ZnO nanoparticles; 91.8 %, 72.9 %, 29.2 % and 85.0 % of 20 ppm of humic acid, 20 ppm of BPA, 20 ppm of phenol and 20 ppm of caffeine respectively under UVA light irradiation. In addition, Y-doped ZnO nanoparticle was found to be highly effective against S. aureus as compared to E. coli. The 9 wt% Y-doped ZnO (9YZnO) nanoparticles have shown no bacterial growth at both minimum inhibitory concentration/minimum bacterial concentration MIC/MBC concentration which served as evidence of the improved antibacterial properties of the modified ZnO nanoparticles. Overall, in this study Y-doped ZnO nanoparticle had shown good performance as photocatalysis material in degrading organic compounds (natural, industrial and consumable organic compounds) and antibacterial material against germ positive microorganism. Considering the developed nanoparticle's performance, its application could be an efficient alternative for water and wastewater treatment applications.

Effect of Co Doping on the Physical Properties and Organic Pollutant Photodegradation Efficiency of ZnO Nanoparticles for Environmental Applications.

This paper presents a comprehensive investigation of the synthesis and characterization of Zn1-xCoxO (0 ≤ x ≤ 0.05) nanopowders using a chemical co-precipitation approach. The structural, morphological, and vibrational properties of the resulting ZnO nanostructures were assessed through X-ray diffraction, scanning electronic microscopy, and Raman spectroscopy to examine the influence of cobalt doping. Remarkably, a notable congruence between the experimental results and the density functional theory (DFT) calculations for the Co-doped ZnO system was achieved. Structural analysis revealed well-crystallized hexagonal wurtzite structures across all samples. The SEM images demonstrated the formation of spherical nanoparticles in all the samples. The vibrational properties confirmed the formation of a hexagonal wurtzite structure, with an additional Raman peak corresponding to the F2g vibrational mode characteristic of the secondary phase of ZnCo2O4 observed at a 5% cobalt doping concentration. Furthermore, a theoretical examination of cobalt doping's impact on the elastic properties of ZnO demonstrated enhanced mechanical behavior, which improves stability, recyclability, and photocatalytic activity. The photocatalytic study of the synthesized compositions for methylene blue (MB) dye degradation over 100 min of UV light irradiation demonstrated that Co doping significantly improves photocatalytic degradation. The material's prolonged lifetime, reduced rate of photogenerated charge carrier recombination, and increased surface area were identified as pivotal factors accelerating the degradation process. Notably, the photocatalyst with a Zn0.99Co0.01O composition exhibited exceptional efficiency compared to that reported in the literature. It demonstrated high removal activity, achieving an efficiency of about 97% in a shorter degradation time. This study underscores the structural and photocatalytic advancements in the ZnO system, particularly at lower cobalt doping concentrations (1%). The developed photocatalyst exhibits promise for environmental applications owing to its superior photocatalytic performance.

Integration of 2D graphene oxide/zinc oxide nanohybrid for enhancement adsorption and photodegradation of organic pollutants

The band gap plays a critical role in determining the photocatalytic efficiency of semiconductor catalysts. Zinc oxide (ZnO) photocatalysts have gained significant attention in sustainable energy and environmental pollution remediation. However, despite its potential, ZnO photocatalytic performance has been hindered by its wide band gap and rapid charge carrier recombination. Numerous techniques have been created to tackle this problem, including doping, nanostructuring, creating oxygen defects, surface modification, and utilizing hybrid nanomaterials. The ZnO and ZnO@GO with different GO contents were synthesized using uncomplicated co-precipitation and solid-state reaction techniques. The ZnO@GO possesses bandgap (Eg) values of 2.5 eV, which is advantageous for achieving more significant photocatalytic activity compared to the unadorned ZnO with Eg values of 3.24 eV. This study investigated the effectiveness of the synthesized catalysts in treating methylene blue (MB) dye through visible light-induced photoreaction. The ZnO@GO nanohybrid exhibited remarkable performance, achieving a decomposition rate of 98.4 % for MB within a 22-minute timeframe. The rate constant of 0.1343 min−1 is significantly greater than that of the unadorned ZnO 0.0448 min−1. Graphene oxide (GO) plays a crucial role in the photocatalytic process by facilitating the gathering and transportation of electrons. This enhancement generates reactive oxygen species and hydroxyl radicals, effectively breaking down MB. The scavenger test results provided compelling evidence that the degradation of MB primarily occurred due to the presence of hydroxyl radicals, which were identified as the most active species in this process.

Comparative study of metal nanoparticles anchored TiO2 using polyoxometalate intermediate in photodegradation of azo dye pollutant in aquatic environments

Herein, metal nanoparticles (Au, Ag, and Pt) are locally deposited on TiO2 with an UV-switchable polyoxometalate intermediate to achieve highly active photocatalyst nanohybrids. The successful preparation of these nanohybrids was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Zeta potential (ZP), and UV–visible spectroscopy. TEM images showed the anchoring of metal nanoparticles of an average size of 20 nm on the TiO2 surface. A comparative study revealed that the bandgap energy was reduced in the order of Pt@PW-TiO2 (2.90 eV) > Ag@PW-TiO2 (2.95 eV) > Au@PW-TiO2 (3.05 eV). Likewise, the photocatalytic efficiency of fabricated nanohybrids was investigated in the degradation of reactive blue 19 (RB19), an azo dye model, under UV–visible light illumination and different experimental conditions. Optimal photodegradation occurred at pH = 3.8 with 0.33 gL−1 of photocatalyst exposed to light for 60 min. Under optimal conditions, the maximum and minimum photodegradation abilities were observed using Pt and Au deposited hybrids. A kinetic study of RB19 photodegradation was also conducted, resulting in pseudo-first order reaction rate constants of 0.0203, 0.025, and 0.0808 min−1, respectively, for the Au@PW-TiO2, Ag@PW-TiO2, and Pt@PW-TiO2 nanohybrids. Finally, the most probable mechanism for RB19 degradation using prepared photocatalysts is presented.

Growth of p/n-type BiFeO3 thin films for construction of a bilayer p–n junction for photodegradation of organic pollutants

BiFeO3 (BFO) films were grown on LaNiO3 (LNO) buffered glass substrates under tailored conditions to exhibit either n-type or p-type conductivity, allowing fabrication of a bilayer p–n junction for efficient photodegradation of organic pollutants.

Carbon pre-protected iron strategy to construct Fe, C-codoped g-C3N4 for effective photodegradation of organic pollutants via hole oxidation mechanism

Improving photocatalytic activity in graphitic carbon nitride (g-C3N4) by enhancing charge transfer and light absorption remains a challenge. Herein, iron-loaded carbon (FeC) was first prepared at low temperature, and then the Fe, C-codoped g-C3N4 (FeC–CN) was synthesized by high temperature thermal copolymerization of FeC with melamine. The carbon shell of FeC prevented the formation of iron oxide during high temperature thermal copolymerization, and Fe as electron channels existed in the interlayer, meanwhile, C atoms of FeC replaced part of the N atoms in the triazine ring. This designed structure facilitates in-plane and interlayer transfer of photogenerated carriers, as well as the separation of photogenerated carriers. Additionally, the UV–visible absorption spectra have demonstrated that the substitution of C atoms can greatly enhance visible light absorption. The catalyst exhibits significantly increased photocatalytic activity and excellent stability compared to g-C3N4. Interestingly, different from the reactive oxygen species-based g-C3N4 catalysis reaction, the degradation of organic pollutants was found to initiate from a hole-involved non-radical pathway. The increased electron transfer facilitates the reduction of O2 via a one-step two-electron pathway to generate hydrogen peroxide.

β-CD-decorated BODIPY-based porous polymers for improved photodegradation

The combination of β-CD and BODIPY allows the formation of high-performance photocatalysts with well-matched adsorption and photodegradation for BPA degradation.

Photodegradation of Rhodamine B by CeO2-CuO Binary Composite Nanoparticles Synthesized by Self-Combustion Method

A novel binary composite CeO2-CuO has been synthesized via self-combustion method employing cerium and copper nitrates, and glycine as fuel, and was investigated as photocatalyst to test the photodegradation of Rhodamine B (RhB) dye with visible light. The nanocomposite has been characterized by thermogravimetric analysis (TGA) to establish the temperature of calcination, X-ray diffraction (XRD) structural and morphologic analysis, scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which enables the chemical characterization/elemental analysis of materials, the photoluminescence (PL), UV-Vis Diffuse reflectance spectroscopy (UV-Vis DRS), measurement of specific surface (SBET ) by N2 adsorption and temperature programmed reduction (TPR) analysis. The XRD diffractogram shows that the composite is majorly composed of 65.2% CeO2 and 34.8 % CuO. The nanoscaled-tested samples have an average particle size of 40 to 65 nm. The energy gap of the material as synthesized was 2.05 eV. The TPR curves show 2 peaks of hydrogen consumption in the sample, corresponding to the decrease (reduction) of CuO particles caused by their interaction with CeO2.The results of the photocatalytic tests show 28% conversion in the photodegradation of RhB organic pollutant during 180 min under visible light. The CeO2- CuO material could be reused for treatment of wastewater during several cycles, which demonstrates its stability for the process.

Exploring multi-stimuli-responsive Pt(ii) complexes: supramolecular self-assembly, lysosome-specific targeted photodynamic therapy and photodegradation of organic pollutants

Developing novel luminescent materials with multi-stimuli-responsiveness and multi-functional properties is vital.

Air promotes efficient and selective CO2 photoreduction with a molecule/semiconductor hybrid photocatalyst: the significant role of simultaneous photodegradation of organic pollutants

A molecule/semiconductor hybrid photocatalyst, consisting of carbon nitride integrated with a molecular Ni(ii)–terpyridine complex, has been employed for air-promoted CO2 photoreduction with the simultaneous photodegradation of tetracycline.

Advancements in visible light-driven micro/nanomotors for photodegradation of environmental pollutants

Recent advances (2020–2024) in visible light-driven motors to enhance pollutant photodegradation are reviewed. An overview of challenges and perspectives for future research is provided.

Porphyrin-containing materials for photodegradation of organic pollutants in wastewaters: a review

Industrialization and town urbanization have led to an exponential need for clean water and new wastewater treatment strategies.

Tunable slow photon effect and local surface plasmon in Ag-immobilized TiO2 inverse opal films for enhancing pollutant photodegradation

Plasmonic silver-decorated TiO2 inverse opal has shown an interesting potential for photocatalysis owing to its physically tunable optical absorbance, highly active area, and flexible fabrication.