Search Results (2,906)

Despite extensive work on FeOCl-based photocatalysts, few studies have explored rare-earth (Ce) doping to simultaneously tune bandgap, suppress charge recombination, and enhance visible light-driven persulfate (PS) activation for the degradation of emerging contaminants. This study synthesized FeOCl/Ce composite photocatalysts via a partial pyrolysis method and systematically characterized their physicochemical properties. The results show that Ce doping significantly lowers the bandgap energy of the photocatalyst, enhances its visible light absorption ability, and effectively suppresses the recombination of photogenerated electron–hole pairs, thereby markedly improving photocatalytic performance under visible light. Analyses including XRD, EDS, XPS, and FT-IR confirm that Ce is incorporated into the FeOCl matrix and modulates the radial growth behavior of FeOCl without altering its intrinsic crystal structure. Morphological observations reveal that FeOCl/Ce exhibits a uniform nanosheet layered structure, with larger particles formed by the aggregation of smaller nanosheets. The nitrogen adsorption–desorption isotherm of FeOCl/Ce shows characteristics of Type IV with a relatively small BET surface area. The broadened optical absorption edge of FeOCl/Ce and the results of PL spectra and I-T curves further confirm its enhanced visible light absorption capacity and reduced electron–hole recombination compared to pure FeOCl. At an initial caffeine (CAF) concentration of 10 μM, FeOCl/Ce dose of 0.5 g/L, PS concentration of 1 mM, and initial pH of 5.06, the FeOCl/Ce-catalyzed PS system under visible light irradiation can degrade 91.2% of CAF within 30 min. An acidic environment is more favorable for CAF degradation, while the presence of SO₄²⁻, Cl⁻, and NO₃⁻ inhibits the process performance to varying degrees, possibly due to competitive adsorption on the photocatalyst surface or quenching of reactive species. Cyclic stability tests show that FeOCl/Ce maintains good catalytic performance over multiple runs. Mechanistic analysis indicates that ^•OH and holes are the dominant reactive species for CAF degradation, while PS mainly acts as an electron acceptor to suppress electron–hole recombination. Overall, the FeOCl/Ce photocatalytic system demonstrates high efficiency, good stability, and visible light responsiveness in CAF degradation, with potential applications for removing CAF and other emerging organic pollutants from aquatic environments. Full article

Iron-based catalysts for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation represent a cornerstone of advanced oxidation processes (AOPs) in environmental remediation, prized for their cost-effectiveness, environmental compatibility, and high catalytic potential. These catalysts, including zero-valent iron, iron oxides, and iron-organic frameworks, activate PMS/PDS through heterogeneous and homogeneous pathways to generate reactive species such as sulfate radicals (SO₄•⁻) and hydroxyl radicals (•OH). However, their large-scale implementation is constrained by inefficient iron cycling, characterized by sluggish Fe³⁺/Fe²⁺ conversion and significant iron precipitation, leading to catalyst passivation and oxidant wastage. This comprehensive review systematically dissects innovative strategies to augment iron cycling efficiency, encompassing advanced material design through elemental doping, heterostructure construction, and defect engineering; system optimization via reductant incorporation, bimetallic synergy, and pH modulation; and external field assistance using light, electricity, or ultrasound. We present a mechanistic deep-dive into these approaches, emphasizing facilitated electron transfer, suppression of iron precipitation, and precise regulation of radical versus non-radical pathways. The performance in degrading persistent organic pollutants—including antibiotics, per- and polyfluoroalkyl substances (PFASs), and pesticides—in complex environmental matrices is critically evaluated. We further discuss practical challenges related to scalability, long-term stability, and secondary environmental risks. Finally, forward-looking directions are proposed, focusing on rational catalyst design, integration of sustainable processes, and scalable implementation, thereby providing a foundational framework for developing next-generation iron-persulfate catalytic systems. Full article

Brilliant blue, as a pigment food additive, has all the characteristics of printing and dyeing wastewater and belongs to persistent and refractory organic compounds. The photocatalysis–Fenton reaction system consists of two parts: photocatalytic reaction and Fenton reaction. Electrons promote the decomposition of H₂O₂ to produce •OH. In addition, the effective separation of e- and h⁺ by light strengthens the direct oxidation of h⁺, and h⁺ reacts directly with OH⁻ to produce •OH, which can further promote the removal of organic pollutants. In this paper, g-C₃N₄ and Fe/g-C₃N₄ photocatalysts were prepared by the thermal polycondensation method. Fe/g-C₃N₄ of 15 wt% can reach 98.59% under the best degradation environment, and the degradation rate of g-C₃N₄ is only 7.6% under the same conditions. The photocatalytic activity of the catalysts was further studied. Through active species capture experiments, it is known that •OH and •O₂⁻ are the main active species in the system, and the action intensity of •OH is greater than that of •O₂⁻. The degradation reaction mechanism is that H₂O₂ combines with Fe²⁺ in Fe/g-C₃N₄ to generate a large amount of •OH and Fe³⁺, and the combination of Fe-N bonds accelerates the cycle of Fe³⁺/Fe²⁺ and promotes the formation of •OH, thereby accelerating the degradation of target pollutants. •O₂⁻ can reduce Fe³⁺ to Fe²⁺, Fe²⁺ reacts with H₂O₂ to produce •OH, which promotes degradation, and •O₂⁻ itself also plays a role in degradation. In addition, under the optimal experimental conditions obtained by response surface experiments, the fitting degree of first-order reaction kinetics is 0.96642, and the fitting degree of second-order reaction kinetics is 0.57884. Therefore, this reaction is more in line with first-order reaction kinetics. The adsorption rate is only proportional to the concentration of Fe/g-C₃N₄. Full article

Cerium-doped titania nanoflowers are obtained by hydrothermal synthesis, with different amounts of cerium (0.3, 0.5, and 1.0 at%). Both undoped nanoflowers (TNF) and Ce-doped TNF (Cex) are tested as photocatalysts in the degradation of the target pollutant (metronidazole) under simulated solar light. The samples are rutile polymorphs with high crystallinity and present a nanoflower-like morphology of about 1 µm in diameter and are made up of nanoscale petals (in the range of 100–300 nm). EDX spectroscopy was coupled with SEM and performed on the Ce-doped samples to determine the elemental composition of the catalysts and the Ce distribution in each sample. Optical and electronic spectroscopies reveal that Ce loading narrows the band gap from 3.0 to 2.8 eV, extending light absorption into the visible range of the spectrum and thus enhancing the photocatalytic activity. The best sample, Ce1, achieved 67% degradation of metronidazole after 360 min under solar irradiation at pH 4, compared to bare TNF, which reached 35%. Reusability tests confirm the chemical stability and photocatalytic efficiency of Ce1 over three cycles, and free-radical trapping experiments confirmed ·O₂⁻ and ·OH as major active species in metronidazole degradation. This study highlights the synergistic impact of morphology and doping on solar-driven organic pollutant degradation. Full article

Plastics play a pivotal role in various industries owing to their versatility in engineering their physical, mechanical, and chemical properties while exploiting their remarkable durability, light-weight nature, and cost-effectiveness. Yet, their widespread use has led to the pollution of Earth’s water systems. Over time, plastic waste degrades into microplastics, particles smaller than 5 mm. Recent studies have highlighted the growing concerns associated with microplastics, especially in bottled beverages, including bottled water, with associated hazards still in the very early stages of being fully understood. Furthermore, the global understanding of the extent of microplastic contamination in the environment and along the food chain remains limited. This study aimed to detect, quantify, and characterise microplastics in bottled drinking water produced and sold in Malta. Samples from five brands were filtered, stained with Nile red, and quantified using fluorescence microscopy. The average microplastic concentration was found to be 35,877 ± 23,542 particles per litre, with 84% of samples exhibiting contamination, which was noted to be statistically significant. The average particle diameter was measured to be 2.3696 ± 0.0035 µm. Raman spectroscopy was used to chemically characterise 10 larger particles per brand (i.e., 50 samples), identifying the presence of cellulose, polyurethane, polymethyl methacrylate, polyethylene, and smaller quantities of other polymers. Morphological analysis classified 36 of the larger particles as fragments and 14 as fibres. Excluding laboratory-introduced contamination, the primary source of microplastic contamination in the analysed bottled water was traced to the bottle caps. Full article

Developing efficient photocatalysts is essential for sustainable wastewater treatment and tackling global water pollution. Graphitic carbon nitride (g-C₃N₄) is a promising material because it is active under visible light and chemically stable. However, its practical application is limited by fast recombination of charge carriers and a low surface area. In this study, we report a simple hydrothermal method to synthesize exfoliated porous g-C₃N₄ (E-PGCN) combined with Ti₃C₂ MXene to form a heterojunction composite that addresses these issues. Various characterization techniques (FTIR, XRD, XPS, SEM, BET) confirmed that adding MXene improves light absorption, increases surface area (53.7 m²/g for the composite versus 21.4 m²/g for bulk g-C₃N₄ (BGCN)), and enhances charge separation at the interface. Under UV-visible light irradiation with Rhodamine B (RhB) as the model pollutant, the E-PGCN/Ti₃C₂ MXene composite containing 3 wt% MXene demonstrated an impressive degradation efficiency of 93.2%. This performance is superior to BGCN (66.6%), E-PGCN (82.5%), and E-PGCN/Ti₃C₂ MXene-5 wt% composites (81%). This is due to the excess Mxene which caused agglomeration and reduced activity. Scavenger studies identified electron radicals as the dominant reactive species, with optimal activity at pH ~4.5. This enhanced performance, 1.4 times greater than BGCN and 1.13 times higher than E-PGCN, is ascribed to the synergistic interplay between the excellent electrical conductivity of MXene and the porous structural features of E-PGCN. This work highlights the importance of morphological engineering and heterojunction design for advancing metal-free photocatalysts, offering a scalable strategy for sustainable water purification. Full article

This study presented the successful synthesis of a visible light responsive Z-scheme BiTmDySbO₇/BiEuO₃ heterojunction photocatalyst (BBHP) via the hydrothermal method, exhibiting outstanding removal efficiency for degrading the metronidazole (MNZ) in wastewater. The BBHP exhibited exceptional photocatalytic activity during the degradation process of the MNZ which was a widely detected pharmaceutical pollutant in aquatic environments. The key to the high photocatalytic activity of the BBHP was the formation of a Z-scheme photogenerated carrier transport channel which existed between BiTmDySbO₇ and BiEuO₃ within the heterojunction structure. This innovative structural design was experimentally confirmed for enhancing the separation efficiency of the photogenerated charge carriers significantly, thereby, the efficient photocatalytic activity of the BBHP was promoted. After visible light irradiation for 130 min, the BBHP achieved a removal efficiency of 99.56% for degrading MNZ and a mineralization rate of 98.11% for removing the total organic carbon (TOC) concentration. In contrast to a single photocatalyst, the removal rate of the MNZ by using the BBHP was 1.14 times that by using the BiEuO₃, 1.26 times that by using the BiTmDySbO₇, and 2.65 times that by using the nitrogen-doped TiO₂ (N-T) under visible light irradiation. The mineralization rate for removing the TOC concentration during the degradation process of the MNZ by using the BBHP was 1.17 times that by using the BiEuO₃, 1.29 times that by using the BiTmDySbO₇, and 2.86 times that by using the N-T under visible light irradiation. The photocatalytic degradation process of the MNZ by using the BBHP followed first-order kinetics model, concurrently, a dynamics rate constant of 0.0345 min⁻¹ was obtained. Furthermore, the BBHP demonstrated excellent stability and durability in accordance with multiple cyclic degradation experiments. According to the capturing radicals experiments and the electron paramagnetic resonance test experiments, it was determined that the hydroxyl radicals (•OH) and the superoxide anions (•O₂⁻) played key role during the photocatalytic degradation process of the MNZ by using the BBHP under visible light irradiation. Finally, the intermediate products that were produced during the degradation process of the MNZ were analyzed by using liquid chromatography-mass spectrometer, as a result, a potential degradation pathway for the MNZ was proposed. Overall, this study could provide valuable references for future research on composite photocatalysts and effectively maintain the safety and sustainable utilization of water resource. Full article

Functional hydrogels are cutting-edge materials that are important in various fields, such as biomedical engineering, agriculture, pollution control, artificial organs, electronics, and domestic products. They are essential to contemporary scientific and industrial advancements because of their adaptability and versatility. The new synthesis techniques and multidimensional applications of different kinds of hydrogels are the goals of this study. The special qualities of hydrogels are one of the main reasons for their widespread use. Because of their stimulus-responsivity, these materials may alter their properties in response to external environmental signals, including light exposure, pH, and temperature. Their biodegradability and biocompatibility make them appropriate for ecological and medicinal applications, while their intrinsic flexibility guarantees adaptation across many applications. Furthermore, the ability of hydrogels to self-heal and be reused enhances their sustainability and efficiency. The preparation of hydrogels with these unique qualities necessitates exacting preparation methods and cautious raw material selection based on the application. To improve their operation and make sure they satisfy the required performance standards in various sectors, a variety of chemical and physical modifications are used. The functional processes of hydrogels in each sector are thoroughly examined in this review, which offers in-depth information on their interactions, efficacy, and the science underlying their uses. By providing a comprehensive overview, this analysis hopes to provide readers with a solid knowledge of potential hydrogels, empowering them to investigate new avenues for research and optimize their uses across a range of sectors. Full article

This study utilizes ambient air quality monitoring data from 13 prefecture-level cities in Heilongjiang Province to systematically analyze the pollution characteristics and dynamic evolution of ozone (O₃) and non-methane hydrocarbons (NMHCs). The findings reveal that overall air quality in Heilongjiang Province has improved substantially in recent years. The concentrations of SO₂, NO₂, PM₁₀, PM_2.5 and CO in 2023 decreased significantly compared with 2015, with an average reduction of 38.7%. However, O₃ concentrations have continued to rise, indicating that O₃ pollution has become an increasingly pressing environmental concern. On an annual scale, the monthly average O₃ concentration in 2023 displayed a “clear single-peak” pattern, reaching its maximum in June, at a concentration of 139 μg/m³. In contrast, the monthly average NMHC concentration exhibited a “distinct double-peak” pattern, with elevated levels in January and December, at 59.4 and 48.35 μg/m³, respectively. From an hourly perspective, the highest O₃ concentrations across the 13 cities occurred between 11:00 and 17:00, while NMHC concentrations showed an opposite trend. Furthermore, during the heating season (October to April of the following year), O₃ and NMHC concentrations increased by 0.78 and 1.56 times, respectively, compared with the non-heating season. In terms of ambient air quality levels, both O₃ and NMHC concentrations exhibited a gradual upward trend under conditions of “excellent”, “good”, and “light pollution”. However, under “moderate pollution”, “heavy pollution”, and “severe pollution” levels, O₃ and NMHC concentrations exhibited irregular patterns, likely due to the interaction of multiple complex factors. O₃ pollution follows a “central concentration and peripheral diffusion” pattern, reflecting the combined influence of human activities and natural conditions. In contrast, NMHC concentrations display pronounced spatial heterogeneity, with low levels in the west and high levels in the east, primarily driven by regional differences in industrial structure and environmental conditions. In summary, this study aims to elucidate the spatiotemporal distribution characteristics of O₃ and NMHC pollution in Heilongjiang Province and their complex relationship with air quality levels, providing a scientific basis for future pollution prevention and control strategies. Subsequent research should focus on identifying the underlying causes of pollution to develop more precise and effective mitigation measures, thereby continuously improving ambient air quality in the province. Full article

Photo(electro)-catalysis has increasingly attracted attention from researchers due to its wide applications in green chemical transformation, including organic synthesis and environmental remediation. As a promising candidate, the n-type semiconductor WO₃ possesses a suitable bandgap (~2.6 eV), good visible-light response, high chemical stability, and multi-electron transfer capability, thus endowing it with enormous potential in heterogeneous photocatalysis (PC) and photoelectrocatalysis (PEC) to address environment and energy issues. In this review, the recent research progress of WO₃-based photo(electro)-catalysts is examined and systematically summarized with regard to construction strategies and various application scenarios. To start with, the research background, functionalization methods and possible reaction mechanisms for WO₃ are introduced in depth. Key influencing factors, including light absorption capacity, charge carrier separation, and reusability, are also analyzed. Then, diverse applications of WO₃ for the elimination of organic pollutants (e.g., persistent organic pollutants and polymeric wastes) and green organic synthesis (i.e., oxidation, reduction, and other reactions) are intentionally discussed to underscore their vast potential in photo(electro)-catalytic performance. Finally, future challenges and insightful perspectives are proposed to explore effective WO₃-based materials. This comprehensive review aims to offer profound insights into innovative exploration of high-performance WO₃ semiconductor catalysts and guide new researchers in this field to better understand their vital roles in green organic synthesis and hazardous pollutants removal. Full article

We present the first dark-sky map of Thailand, derived from calibrated Visible Infrared Imaging Radiometer Suite (VIIRS) satellite data spanning 2012–2023. Artificial night-sky brightness was classified into 14 levels, with Classes 1–9 defined as potential dark-sky areas where the Milky Way remains visible. International comparisons with the United Kingdom, Chile, and Botswana reveal that Thailand has undergone the steepest decline, losing 15.4% of pristine skies since 2012, while the UK remained stable (+0.8%), Botswana nearly unchanged (−0.7%), and Chile moderately degraded (−5.3%). A correlation analysis shows strong negative associations between potential dark-sky area and both GDP ($r=-0.65$) and population ($r=-0.68$), while inflation ($r=0.26$) and unemployment ($r=0.24$) exhibit weak influence. Five algorithms, including GLM and machine learning models, were tested; among them, the Decision Tree achieved the lowest relative error ($0.4\%\pm 0.3\%$), with ensemble methods and GLM performing comparably and Deep Learning being less accurate. By 2023, over 60% of Thais lived under skies too bright to observe the Milky Way by naked eye, and one-fifth were exposed to intensities preventing dark adaptation. Thailand’s rapid transition to LED street lighting after 2015, while energy-efficient, has intensified skyglow. Protecting remaining dark-sky areas requires urgent policies, linking conservation to human health, biodiversity, cultural heritage, and sustainable development. Full article

Astrotourism is gaining international recognition as a practice that integrates science, culture and sustainability, addressing global challenges such as light pollution and fostering inclusive local development. Although its environmental and economic impacts are widely acknowledged, its potential as a driver of social innovation remains underexplored. This study addresses this gap by examining how astrotourism activates social innovation across multiple governance scales. The objective is to identify the mechanisms, enabling conditions, and territorial arrangements through which astrotourism operates as social innovation in peripheral contexts. The research adopts a qualitative and exploratory approach, based on documentary and bibliographic analysis of four international cases: Alfa Aldea in Chile, Dark Sky Alqueva in Portugal, the Jasper Dark Sky Festival in Canada, and the National Astrotourism Strategy in South Africa. A comparative framework was applied to identify three recurrent dimensions of social innovation—social capital, redistribution of power, and collaborative responses to crises—drawing on both classical and contemporary literature. Findings show that, despite institutional and territorial differences, all four cases demonstrate the capacity of astrotourism to build trust networks, strengthen community protagonism, and generate adaptive responses to socioeconomic vulnerabilities. The study proposes an interpretive matrix that outlines pathways of social innovation, offering policymakers tools to design multi-scalar strategies that connect community initiatives with national frameworks to achieve the Sustainable Development Goals. Beyond astrotourism, the framework also provides insights for other sustainable tourism modalities based on natural and cultural heritage. Full article

Imidacloprid (IMI), a neonicotinoid insecticide, is widely recognized for its environmental persistence and toxicity to non-target aquatic organisms. Extended photoperiod exposure (EPE), an emerging anthropogenic stressor, further disrupts aquatic ecosystems by altering physiological and biological processes. However, their combined impacts on aquatic species remain insufficiently explored. This study evaluates the synergistic effects of IMI and EPE on Procambarus clarkii, an ecologically and economically significant crayfish species. Crayfish were exposed to 25 µg/L IMI under normal photoperiod (1000 lx, L:D = 12:12 h) and additional intensified and extended photoperiod (5000 lx, L:D = 18:6 h) treatments over one month. Key parameters, including survival rate, growth performance, oxidative stress markers, immune enzyme activities, neuroendocrine hormone levels, and gene expression, were assessed. The results indicate that EPE significantly amplifies the adverse effects of IMI. EPE reduced survival rates and growth performance, particularly in the 5000 lx group. IMI combined with EPE markedly elevated oxidative stress, as evidenced by increased malondialdehyde (MDA) levels and altered activities of superoxide dismutase (SOD) and catalase (CAT). Immune functions were impaired, with significant reductions in lysozyme (LZM) and acid phosphatase (ACP). Neuroendocrine disruption was observed through suppressed melatonin (MT) levels under EPE. Gene-expression analysis revealed upregulation of oxidative stress and apoptotic pathways (Cu/Zn-SOD, CAT and caspase-3) and downregulation of anti-apoptotic genes (bcl-2) and molt-inhibiting hormone (MIH). This study demonstrates that EPE exacerbates IMI-induced physiological and biochemical disruptions in P. clarkii. The findings highlight the pressing need for integrated management strategies addressing chemical and light pollution to protect aquatic ecosystems and sustain economically important species like crayfish. Full article

To enhance the photocatalytic performance of TiO₂ nanotubes (NTs) for the degradation of Amido Black as an organic pollutant, electrodeposition of bismuth vanadate (BiVO₄) nanostructures was successfully applied. The effect of electrodeposited BiVO₄ (25 s, 50 s, 150 s, 250 s), followed by a thermal treatment on TiO₂-NTs, was studied. The structures of the as-prepared samples were characterized by X-ray diffraction (XRD). Morphological behavior was investigated using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), both coupled with EDX. Optical characterizations were performed using photoluminescence and diffuse reflectance spectroscopy. The BiVO₄/TiO₂ NTs sample with 50 s deposition time gave the highest photocatalytic performance for Amido Black degradation, 99.4% after 150 min under UV light. This result has been achieved due to the structure and the optical properties of the sample. The heterojunction of both catalysts showed the synergetic effect on the photocatalytic performance where they remained stable after five cycling runs. Furthermore, quenching tests were conducted and proved that superoxide radicals (O₂^•) are the main active species during photodegradation process. Full article

Nitrogen oxides (NO_x) are major atmospheric pollutants, and their escalating emissions, driven by rapid economic development and urbanization, pose a severe threat to both the ecological environment and human health. Conventional denitrification technologies are often hampered by high costs, significant energy consumption, and stringent operational conditions, making them increasingly inadequate in the face of tightening environmental regulations. In this context, photocatalytic technology, particularly systems based on graphitic carbon nitride (g-C₃N₄), has garnered significant research interest for NO_x removal due to its visible-light responsiveness, high stability, and environmental benignity. To advance the performance of g-C₃N₄, numerous modification strategies have been explored, including morphology control, elemental doping, defect engineering, and heterostructure construction. These approaches effectively broaden the light absorption range, enhance the separation efficiency of photogenerated electron-hole pairs, and improve the adsorption and conversion capacities for NO_x. Notably, constructing heterojunctions between g-C₃N₄ and other materials (e.g., metal oxides, noble metals, metal–organic frameworks (MOFs)) has proven highly effective in boosting catalytic activity and stability. Furthermore, the underlying photocatalytic mechanisms, encompassing the generation and migration pathways of charge carriers, the redox reaction pathways of NO_x, and the influence of external factors like light intensity and reaction temperature, have been extensively investigated. From an application perspective, g-C₃N₄-based photocatalysis demonstrates considerable potential in flue gas denitrification, vehicle exhaust purification, and air purification. Despite these advancements, several challenges remain, such as limited solar energy utilization, rapid charge carrier recombination, and insufficient long-term stability, which hinder large-scale implementation. Future research should focus on further optimizing the material structure, developing greener synthesis routes, enhancing catalyst stability and poison resistance, and advancing cost-effective engineering applications to facilitate the practical deployment of g-C₃N₄-based photocatalytic technology in air pollution control. Full article