Organic Pollutants Research Articles

Automated pretreatment of environmental water samples and non-targeted intelligent screening of organic compounds based on machine experiments

The complexity of environmental pollutants poses significant challenges for monitoring and analysis, especially with the emergence of numerous emerging contaminants. Traditional analysis methods rely mainly on laboratory analysis, which involves labor-intensive and time-consuming sample preparation procedures and non-target data analysis, greatly limiting the rapid detection of water organic pollutants. In this study, we designed a robot experimenter combined with GC × GC-TOFMS. By configuring self-developed automated analysis software, we established a fully automated process from sample collection to data characterization, for the analysis of organic pollutants. We validated the method with 111 organic standards compounds. The robot performed 2577 actions covering the entire workflow, from water sample collection to sample pre-treatment. The integration of mass spectrometry and related software enabled the automatic analysis of emerging hazardous contaminants, from sampling to the output of detection results. The results showed the automated process could qualitatively identify all compounds and demonstrated good linearity, low detection limits, and excellent quantitative ability within the range of 0.04–0.4 mg/L. The average recoveries of 82.89 % of the samples ranged from 70 % to 120 % (relative standard deviation (RSD) <15 %) at different spiked concentrations. This indicated that the established method could be used for non-targeted analysis of emerging contaminants in environmental water samples. We applied the method to samples from wastewater treatment plants and river sections, identifying 1,902 compounds across 26 categories, including 6 known hazardous contaminants found in all samples. The relative content of these characteristic compounds will inform whether treated wastewater meets discharge standards and aid in tracing the sources of pollutants. Therefore, the development of this fully automated machine experimental method enables real-time and online automatic analysis of organic pollutants in environmental water. The establishment of characteristic fingerprints can provide technical support for early warning and traceability of water quality.

Green synthesized N-CQDs@NiO nanocomposites for efficient photocatalytic degradation of organic pollutants from water

The alarming increase in environmental contamination caused by the untreated release of hazardous phenolic compounds such as 3-Aminophenol (3-AP) and Safranin-O (SO) dye has become a serious global issue. Traditional cleanup methods have limitations, so we must decline practical approaches that do not harm the environment. The purpose of this research was to develop a new catalytic system for advanced oxidation processes (AOPs) by combining nitrogen-doped carbon quantum dots (N-CQDs) with nickel oxide (NiO) nanocomposites. Citrus limetta leaves were utilized to create N-CQDs, which were then combined with NiO nanoparticles via green tea extract. A thorough investigation revealed that N-CQDs were successfully added to the NiO matrix, increasing the nanocomposite’s structural stability and photocatalytic properties. Sunlight-based tests showed that N-CQDs@NiO nanocomposites were better at breaking down chemicals than NiO nanoparticles alone, with 99 % efficiency for 3-AP and 98 % efficiency for SO. The higher efficiency was due to N-CQDs’ better ability to adsorb substances, keep particles from sticking together, and separate charges effectively, which made it easier for reactive species like superoxide anions and hydroxyl radicals to form. This work shows that N-CQDs@NiO nanocomposites could clean up the environment and provide a long-term way to break down persistent organic pollutants in wastewater. In the future, researchers will try to improve the process of making these nanocomposites and find ways to use them in real wastewater treatment systems.

Synthesis of Novel Fe-CNs-P/S Carbon Materials for Sustainable Water Treatment: Activation of Persulfate for Efficient Tetracycline Degradation

This study presents a novel Fe-CNs-P/S carbon composite material, synthesized by doping elements P and S into NH2-MIL-101 (Fe) using the carbonization method. The material’s application in sustainable water treatment was evaluated, focusing on its effectiveness in activating persulfate for pollutant degradation. The research thoroughly investigates the synthesis process, structural characteristics, and performance in degrading pollutants. The results indicate that Fe-CNs-P/S-5 with 50% P and S co-doping is higher than that of other samples, where the degradation rate of TC in 30 min is as high as 98.11% under the optimum conditions, that is temperature at 25 °C, 0.05 g/L of catalyst concentration, and 0.2 g/L of PMS concentration. The composite material demonstrates robust versatility and stability, maintaining high degradation efficiency across multiple organic pollutants, with no significant reduction in catalytic performance after four cycles. Furthermore, the free radical quenching experiments display that the singlet oxygen 1O2 is the main active species. It is demonstrated that the doping of P and S play a role in the enhancement of PMS activation over the Fe-CNs-P/S catalyst. This material demonstrates remarkable efficacy in treating a range of organic contaminants and exhibits excellent reusability, presenting a promising approach for enhancing sustainability in water treatment applications.

A comprehensive Review into Emission Sources, Formation Mechanisms, Ecological Effects, and Biotransformation Routes of Halogenated Polycyclic Aromatic Hydrocarbons (HPAHs)

Halogenated polycyclic aromatic hydrocarbons (HPAHs, H = F, Cl, Br) are a new class of PAHs derivatives that mainly originate from the incomplete combustion of halogen-laden materials and via metallurgical operations. These compounds circulate extensively in various environmental matrices. This survey provides a comprehensive review on governing synthesis routes of HPAHs, their environmental occurrence, and their health and ecological effects. The review comprehensively enlists and presents emission sources of these emerging organic pollutants into the air that serves as their main reservoir. The formation of HPAHs ensues through successive addition reactions of related precursors accompanied by ring cyclization steps; in addition to direct unimolecular fragmentation of parents halogenated. Halogenation of parent PAHs rapidly occurs in saline ecosystems, thus multiplying the availability of these notorious compounds in the environment. Certain HPAHs appear to be more carcinogenic than dioxins. Transmission routes of HPAHs from their emission sources to water bodies, soil, aquatic life, plants, terrestrial animals, and humans are well-documented. Later, the direct and indirect diffusion of HPAHs from air to the biotic (plants, animals, humans) and abiotic components (soil, water, sediments) are described in detail. The study concludes that HPAHs are permeable to the carbon matrices resulting in the alleviation of the source-to-sink interface. As a potential future perspective, understanding the transmission interfaces lays a foundation to intervene in the introduction of these toxicants into the food chain.

Ecologically friendly remediation of groundwater sulfamethoxazole contamination: Biologically synergistic degradation by thermally modified activated carbon-activated peracetic acid in porous media

This study examines the efficacy and environmental impact of peracetic acid (PAA) activated by thermally modified activated carbon (AC600) for degrading antibiotics in actual groundwater. Laboratory-scale experiments evaluated the system's effects on contaminant degradation, ecological balance, and substance cycling in the hyporheic zone. Our findings demonstrated the effectiveness of the AC600/PAA system in removing sulfamethoxazole (SMX) from groundwater porous media. Additionally, the AC600/PAA system synergistically interacted with the in-situ microbiota of the hyporheic zone, producing more fragmented degradation products without increasing mixed toxicity. Bacterial abundance increased post-reaction, with notable alterations in the bacterial community and enhanced bacterial metabolism. Key genera such as Lysobacter thrived in the treated environment, playing critical roles in microbiota modification and SMX degradation. The pH remained stable before and after the reaction, while dissolved organic carbon content increased. Overall, our results highlight the promising potential of PAA activation by carbonaceous materials as a low-impact, ecologically friendly technology for in-situ remediation of organic pollutants in groundwater, characterized by high compatibility and biosynthesis.

Light Precipitation rather than Total Precipitation Determines Aerosol Wet Removal.

Precipitation scavenging is an important sink for both organic and inorganic pollutants in the atmosphere. However, there has been controversy over the relative importance of different precipitation characteristics (i.e., the precipitation amount, intensity, frequency, and duration) in the removal of air pollutants. It is critical to reach a consensus on which precipitation characteristics are most significant for aerosol wet removal. In this study, the analysis of multisource in situ observations of aerosol wet deposition worldwide indicates that the precipitation frequency plays a first-order role in scavenging aerosols. This is because large amounts of air pollutants are efficiently removed at precipitation initiation. As the duration and amount of precipitation increase, the scavenging efficiency decreases sharply. Consequently, it is featured that light precipitation, due to its high frequency of occurrence, rather than total precipitation, determines climatological aerosol wet deposition. To further confirm this, a state-of-the-art global climate model with convection resolved is modified to reduce the light precipitation frequency in both stratiform and convective cloud regimes. Results show widespread increases in aerosol optical depth (AOD) due to the reduced wet deposition. The spatial distribution of aerosol wet deposition changes resembles that of changes in the light precipitation frequency rather than that of total precipitation changes. These findings are consistent with those from the Coupled Model Intercomparison Project Phase 6 multimodel simulations, which show that the intermodel uncertainty in simulated AOD correlates more strongly with the uncertainty in light precipitation frequency than with that in total precipitation.

Full-spectral response of mesoporous Z-scheme nanoheterojunction NaYF4:Yb,Tm@ZnO/BiOI photocatalysts for simultaneous contaminant and pathogen elimination in wastewater

The increasing contamination of water bodies demands effective and economical solutions for wastewater treatment. This study introduces a novel Z-scheme photocatalyst, NaYF4:Yb,Tm@ZnO/BiOI (UZB), synthesized via a simple chemical route. UZB exhibits exceptional photocatalytic degradation efficiencies of 95.1 %, 88.7 %, and 56.3 % for methyl orange under full spectrum, visible, and near-infrared light, respectively. The integration of heterostructures within UZB promotes efficient charge carrier separation, significantly boosting its photocatalytic activity. When applied to actual wastewater, UZB markedly reduces chemical oxygen demand (COD) and total organic carbon (TOC) by 94.1 % and 53.2 %, respectively, and also effectively decreases turbidity and ammonia concentrations. Additionally, UZB shows strong antibacterial effects against S. aureus and E. coli, with inhibition rates of 93.9 % and 92.0 %, though some cytotoxicity is noted. These results underscore UZB's potential as a highly efficient photocatalyst for the simultaneous removal of organic pollutants and pathogens from wastewater, supporting its application in industrial water treatment systems.

A Study on the Diversity of Planktons of Urban and Rural Ponds of Kokrajhar District, Assam, India

Due to rapid urbanization, many aquatic habitats are now under severe eutrophication because of waste contaminated soil. Therefore, it is essential to assess the status of aquatic ecosystem surrounding us. The present study was conducted for the study of diversity of planktons which are indicator of aquatic ecosystem of two urban and two rural ponds of Kokrajhar district, Assam. The present study reveals a total of 37 species of planktons of which 23 species represents phytoplankton and 14 species represent zooplankton. The most pollution-tolerant species of Euglena, Navicula, Nitzschia, Ankistrodesmus, Phacus,Pinnularia and Scenedesmus were recorded indicating the highest degree of organic pollution. This plankton study explore that water quality has reached its threshold level and therefore, it needs some corrective measures to maintain the water quality from further deterioration in the study area.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Eco-friendly synthesis and applications of graphene-titanium dioxide nanocomposites for pollutant degradation and energy storage

An innovative, eco-friendly method has been developed to synthesize reduced graphene oxide (rGO) sheets using orange peel extract. Following this, TiO2 nanoparticles are anchored to the rGO sheets through a hydrothermal process, resulting in an rGO/TiO2 nanocomposite (GTO/NC). This study utilized standard characterization techniques to confirm the formation of GTO/NC-1 and GTO/NC-2. Comparative analysis demonstrated that orange peel extract exhibits reducing capabilities compared to other natural reducers. The resulting GTO/NC-1 and GTO/NC-2, specifically GTO/NC-2, enhanced catalytic performance in degrading methyl orange a prevalent organic pollutant in various industrial applications. This nanocomposite achieved a turnover frequency of 0.003 mg MO/mg catalyst/min and displayed remarkable durability, enduring 3.0 cycles with robust first-order rate constants of 0.0193 min−1. Additionally, the electrochemical properties of GTO/NC-1 and GTO/NC-2 as electrode materials were assessed, revealing a specific capacitance of 320.0 Fg−1 at a current density of 1.0 Ag−1 and maintaining about 86.8 % of its initial capacitance after various charge–discharge cycles. These properties highlight the potential of GTO/NC-1 and GTO/NC-2 as both efficient catalysts for environmental remediation and durable materials for energy storage applications, offering substantial benefits for sustainable technology solutions.

Synergistic catalytic degradation of Methotrexate using Ce-based high-entropy metal oxides: Insights from DFT calculations and CWPO performance

Methotrexate (MTX), a widely used anticancer drug, is a refractory organic pollutant posing serious threats to ecosystems and human health. This study focuses on the development of a novel catalyst composed of Ce-based high-entropy metal oxides (NHEMO) supported on nepheline for the catalytic wet peroxide oxidation (CWPO) process, targeting MTX degradation in simulated wastewater. The NHEMO catalyst exhibited a unique high-entropy structure that enhances catalytic performance by facilitating diverse electronic interactions, which was confirmed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showing a well-defined crystal structure and uniform dispersion of metal oxides. Additionally, X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) revealed a stable metal composition and high oxidation states of active metal sites. At a reaction temperature of 160 °C, with a residence time of 150 s and an oxidation coefficient of 5, the catalyst achieved a MTX removal rate of 93.49 % and a chemical oxygen demand (COD) removal of 99.95 %. Density Functional Theory (DFT) calculations further demonstrated that H2O2 decomposes into both adsorbed (surface-bound) and free (solution-phase) hydroxyl radicals (·OH). These radicals synergistically degrade MTX through both radical and non-radical pathways, ensuring comprehensive pollutant breakdown. The catalyst also showed excellent stability and a very low metal dissolution rate during the reaction, maintaining high catalytic activity after repeated recycling. This catalyst offers high cost-effectiveness, activity, and stability, providing a promising solution for treating refractory organic pollutants in pharmaceutical wastewater.

Environmental level of lanthanum increased phytoextraction of co-occurring cadmium and polystyrene nanoplastics by Sedum alfredii

Phytoextraction based on hyperaccumulators is a sustainable bioremediation technology. However, hyperaccumulators can only accumulate a single type of pollutants and need long remediation times, inhibiting simultaneous phytoextraction of co-occurring inorganic and organic pollutants. Here, the study indicated that the environmental level of lanthanum, as an emerging pollutant, was absorbed by leaves and induced endocytosis from leaves to roots (systemic endocytosis) in Sedum alfredii. Cadmium and polystyrene nanoplastics were simultaneously absorbed by root cells through systemic endocytosis, increasing the accumulation of these pollutants in Sedum alfredii. One possible mechanism of improving phytoextraction of co-occurring cadmium and polystyrene nanoplastics is that the lanthanum-induced system endocytosis increased the nutrient absorption of Sedum alfredii, thus increasing the activity of antioxidant enzymes, enhancing photosynthesis, biomass, and plant tolerance. These findings provide a new empirical basis and strategy for the simultaneous phytoremediation of co-occurring inorganic and organic pollutants in environments.

Revealing the reaction mechanism of the novel p-n heterojunction Mn3O4-C3N4 in efficient activation of chlorite to degrade organic pollutants under piezoelectric catalysis

This study constructed a p-n heterojunction Mn3O4-CN by loading Mn3O4 on g-C3N4 (CN), effectively activating chlorite to degrade organic pollutants under piezoelectric effect. The rate of sulfamethoxazole (SMX) degradation in the piezo/Mn3O4-CN/chlorite combination was 0.0346 min−1, surpassing piezo/CN/chlorite and Mn3O4/chlorite systems by 21.63 and 3.26 times, respectively. Experimental verification and theoretical calculation showed that Mn3O4-CN had a stronger piezoelectric response and adsorbed chlorite (-1.682 eV) better than CN (-0.615 eV) and Mn3O4 (-1.093 eV), contributing to the activation of chlorite and efficient pollutant degradation. The Mn(II)/Mn(III)/Mn(IV) cycle during piezoelectric activation of chlorite by p-n heterojunction promoted SMX degradation, with chlorine dioxide (ClO2) and Mn(IV) as dominant reactive species. Furthermore, the piezo/Mn3O4-CN/chlorite system exhibited remarkable stability, environmental safety and wide application potential. This research offered fresh insights and practical guidelines for harnessing mechanical activation of chlorite for efficient organic pollutant degradation in water, advancing water treatment technology.

Hygienic assessment of heavy metal and organic compounds pollution in snow cover of a multi-industrial city

Introduction. One of the leading health risk factors is atmospheric air pollution, the state of which can be indirectly assessed by the content of a wide range of pollutants in snow and soil cover. Materials and methods. The study analyzed data on deposits of polycyclic aromatic compounds (PAHs), heavy metals (HMs) and petroleum hydrocarbons (PHs) in the snow of different functional zones of the agglomeration. Physicochemical research methods were used. Results. The content of ΣPAHs was found to range from 412.8 to 2843.7 ng/L. The highest concentrations of ∑PAHs were observed in the residential area in the square (point 10) – 2843.7 ng/L; and on the border of the sanitary protection and residential zones in the area of the Yuzhnaya station (point 3) – 1758.2 ng/L. The share of benzo(a)pyrene (B(a)P) from ∑PAH ranged from 2.9 to 9.7%. PHs levels ranged from 51.0–117.0 μg/L. The difference in the range of fluctuations in values was most evident in the content of individual PAHs: B(a)P (16.13 times), Ant (12.05 times) and B(g,h,i)P (11.56 times ), mercury (17.53 times), zinc (9 times) and manganese (8.58 times); metals: cadmium (1.89 times), copper (1.75 times), and lead (1.47 times). Limitations. Sampling and features of snow cover contamination by atmospheric precipitation in the dynamics of the winter season. Conclusion. Concentrations of PAHs and HM varied in different ranges of values and had a non-uniform spatial distribution over the territory. Direct links were found between the content of B(a)P and other polyarenes in the snow cover.

Chiral FeNC single-atom nanozymes with multi-enzyme activity for dye degradation

The application of single-atom nanozymes in the removal of organic dye pollution by advanced oxidation process (AOPs) have been widely concerned. However, the application of single-atom nanozymes in AOPs is rarely reported. In this work, a kind of Fe-and nitrogen-codoped carbon (Fe-N-C) with peroxidase-like and laccase-like activities was prepared by calcining Fe-doped MOF, then the chiral peptides were introduced into single-atom nanozymes, and chiral single-atom nanozymes (L-Au@FeNC) were successfully prepared. The L-Au@FeNC can effectively activate PMS to degrade different kinds of organic dyes and also shows high cycle stability. In addition, the results of quenching experiment and electron paramagnetic resonance (EPR) test show that 1O2 produced during PMS activation plays an important role in the degradation of organic dyes, and O2·-, ·OH, and SO4·- are also produced during PMS activation, suggesting that the degradation of selected organic dyes include radical and non-radical pathways. It should be noted that L-Au@FeNC showed higher activity than D-Au@FeNC in enzyme-like activity (laccase-like and peroxidase-like) experiment and organic dye degradation, the results of molecular docking simulation indicated that it may be due to the better binding force of L peptide to the substrate of enzyme-like reaction and organic dye than D peptide. This chiral single-atom nanozymes provide a new idea for the application of organic dye degradation and enzyme-like catalysis design.

Carbon Ink Enhanced Calcium Alginate-Based Hydrogel with Response Surface Methodology Optimized for Solar-Driven Salt-Tolerant Desalination.

The global shortage of freshwater resources is becoming more and more serious; therefore, it is necessary to obtain freshwater by desalinating seawater resources. Solar-driven interfacial photothermal evaporation, which is an environmentally friendly and energy-efficient technology, has been used to desalinate seawater for water purification and production. Herein, the IPCA hydrogel with abundant pores consisting of carbon ink as a photothermal conversion material and PU sponge loaded with calcium alginate as a water transport medium was successfully prepared and used to obtain portable water. The parameters of the synthesized IPCA are optimized by Response Surface Methodology analysis, and it was found that the IPCA exhibits a high evaporation efficiency of 3.779 kg m-2 h-1 and up to 95.98% of photothermal conversion capacity under one solar intensity. It maintains a high evaporation efficiency and salt resistance after 10 cycles of evaporation in actual seawater. Moreover, IPCA shows a high removal of various organic dye pollutants in wastewater. The results suggest a new approach for the preparation of simple, efficient, and green solar evaporators in practical application.

Investigation and risk assessment of dioxins and dioxin-like PCBs in main aquatic products in market from Shanghai

Dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) are widespread persistent organic pollutants with high toxicity. Aquatic product is an important source of high-quality protein, and understanding the occurrence and risk of PCDD/Fs and dl-PCBs in aquatic products is of vital significance. In this study, 101 aquatic product samples (including freshwater fish, freshwater shrimp, freshwater crab, sea fish, sea shrimp, sea crab, and ocean mollusk) sold in Shanghai market from 2017 to 2023 were collected and the concentrations of PCDD/Fs and dl-PCBs were analyzed. In general, although the collected samples display high detection rate (15.4 %–100 % for PCDD/Fs and 76.9 %–100 % for dl-PCBs), the pollution levels of PCDD/Fs and dl-PCBs were relatively low in terms of concentrations as well as toxic equivalent (TEQ). Compared with other species, freshwater crabs exhibit higher contamination to PCDD/Fs and dl-PCBs with detection rates of 100 % and the mean TEQ value of 4.008 pg TEQ g−1 ww, which was also at similar or lower level to the existing reports. Besides, the dl-PCBs pollution in sea fish and sea crab is also at relatively high level compared with other species. Furthermore, the PCDD/Fs level in aquatic products is much lower than the dl-PCBs. After the dietary exposure risk assessment, the mean and 95th percentile values of monthly ∑PCDD/Fs + dl-PCBs exposure via aquatic products for Shanghai residents aged ≥ 3 years old were 7.988 and 25.339 pg TEQ/kg bw/month, respectively, lower than the provisional monthly tolerable intake (PTMI, 70 pg TEQ/kg bw/month) set by the JECFA, indicating the acceptable and low exposure risk. This study provides fundamental information about the occurrence characteristics and risk assessment of PCDD/Fs and dl-PCBs in aquatic products, and can act as reference basis for the formulation of control regulations and limit standards of PCDD/Fs and dl-PCBs in aquatic products in China.

Utilization of waste citrus limetta peel for the green synthesis of iron catalyst and its subsequent application in fluidized-bed Fenton-like process for environmental sustainable treatment of organic pollutant

This work focuses on the environmental friendly synthesis of an iron-based catalyst utilizing extract from waste citrus limetta peels. The main objective is to encourage the sustainable use of bio-waste materials in catalytic processes. This innovative method demonstrates the efficacy of bio-derived materials in catalysis by removing the need for hazardous chemicals. The green-synthesized catalyst was analyzed using many characterization methods, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). These analyzed results give insightful information on the physicochemical properties of green-synthesized catalysts. Furthermore, the prepared catalyst was utilized in a fluidized-bed reactor to facilitate the Fenton degradation of dye effluent, with a specific focus on the commonly used Eosin yellow (EY) dye. The iron catalyst derived from plant-based waste material accomplished an impressive 98% degradation of EY within a 90-minute time frame under optimized working conditions, using a minimal quantity of catalyst. An in-depth analysis was conducted to study the kinetics and process mass transfer in order to improve the comprehension of catalytic processes occurring in the fluidized-bed reactor. The Fenton decomposition of dye effluent is likely to be explained by first-order reaction kinetics. Additionally, confirmed enhanced catalytic durability and decreased deactivation of surface sites of the prepared catalyst after three consecutive oxidation cycles. These findings underscore the potential of this approach in sustainable wastewater treatment, highlighting both its efficiency and cost-effectiveness.

Ternary Boron Carbon Nitride nanosheets with improved and controllable linear and nonlinear optical response for efficient photocatalytic performance

This work reports the systematic variation of linear and nonlinear optical (NLO) properties of ternary boron carbon nitride (BCN) nanosheets with varying carbon concentrations. These nanosheets are synthesized by the thermal substitutional method to modulate the band-gap of BCN nanosheets by varying the hBN and graphene domain ratios which is confirmed through UV–Vis absorption spectroscopy. The third-order optical nonlinearity of nanosheets was explored through the Z-scan technique. With increases in both carbon content and laser power, samples' NLO properties have shifted from saturable absorption to reverse saturable absorption. The enhanced nonlinearity with carbon concentration in BCN samples was responsible for higher photoinduced charge separation time. In UV–Vis driven photoreduction of organic pollutants, BCN nanosheets with a decreased bandgap and an increased charge separation time show higher catalytic efficiency. Therefore, based on the combined effect of many processes, the results revealed that the BCN nanosheets displayed greater potential for photoinduced reduction.

Synthesis of ZnPc/BiVO4 Z-Scheme Heterojunction for Enhanced Photocatalytic Degradation of Tetracycline Under Visible Light Irradiation

The construction of semiconductor heterojunctions is an effective strategy to improve the photocatalytic degradation efficiency of organic pollutants. Herein, ZnPc/BiVO4 Z-scheme heterojunction was synthesized via a physical mixing method and was used for the photocatalytic degradation of tetracycline (TC) under visible light irradiation. Compared with BiVO4 and ZnPc, the 15ZnPc/BiVO4 sample exhibited improved light absorption capacity, and the electron-hole separation efficiency and redox capacity were enhanced due to the formation of the Z-scheme heterojunction. The 15ZnPc/BiVO4 composite exhibited an optimal TC degradation rate of 83.1% within 120 min. Additionally, 15ZnPc/BiVO4 exhibited excellent stability in cycling experiments, which maintained a high TC degradation rate of 79.5% after four cycles. Free radical trapping experiments indicated that superoxide radicals (O2−) were the main active substances in the photocatalytic degradation of TC.