Toxic Contaminants Research Articles

Assessment of potentially toxic element contamination in wetland sediments of Boracay Island, Philippines

Boracay Island, Philippines, famous for its white sand beaches, has wetlands increasingly threatened by human activities. This study evaluated the ecological state of Boracay Island's wetlands and assessed the consequences of anthropogenic activities on sediment quality. Results showed that sediments from Wetland Nos. 3 and 4 have higher concentrations of potentially toxic elements (PTEs) than Wetland No. 1. Comparative analysis with other Southeast Asian wetlands revealed that Boracay's sediments contain the highest average values of As, Cd, Cu, Ni, Zn. Enrichment factor values suggest that the moderate enrichment of Cd, Cr, Cu, Mo, Pb, and Zn in the wetland sediments can be attributed to anthropogenic activities on the island. Elevated concentrations of Cr, Cu, and Zn above interim sediment quality guidelines indicate occasional adverse biological effects on aquatic biota. These findings provide a crucial baseline for future pollution monitoring and highlight the need for ongoing conservation efforts in Boracay's wetlands.

Sustainable stabilization/solidification of Cu-contaminated seasonal frozen soil by epoxy resin: environmental risk assessment and engineering applicability

There are significantly toxic Cu contaminants in seasonal frozen soil areas under industrial production and mineral exploitation. However, the hydration reactions of mainstream alkaline curing agents such as cement are disturbed by the solidification and thawing of moisture, and their solidification/stabilization is ineffective to heavy metals. Therefore, there is an urgent requirement to optimize the use of current curing agents to improve the solidification/stabilization (S/S) effect of Cu contaminants in seasonal frozen soil areas. In this study, the Epoxy resin (EP) with excellent waterproofing and frost resistance was incorporated into artificially prepared Cu-contaminated soil to maintain a steady engineering application strength and inhibit the outward diffusion of toxic Cu contaminants under freeze-thaw cycles. The freeze-thaw resistance of EP-cured Cu-contaminated soil and the feasibility of EP remediation technology have been investigated, including mechanical properties, environmental effects and microstructure. The decline in mechanical strength and the increment in Cu leaching during freeze-thaw cycles are effectively suppressed by the remediation of EP. Even after 8 freeze-thaw cycles, there is merely a mechanical strength decline of 5%, solely a secondary Cu leaching of 4.74mg/L, and astonishingly a leachable index of 11.70 in the specimens with 12% EP dosage. The expansion phenomenon of pores and clay fractures under freeze-thaw cycles were gradually alleviated after incorporation of EP. The above results demonstrate the Cu-contaminated seasonal frozen soil remedied by EP are high-strength, basically non-toxic, and environmentally friendly material which are suitable for in-situ stabilization/solidification in seasonal frozen soil areas.

Unveiling new insights into photocatalytic enhancement of p-n BiVO4-OV/NiMoO4 Heterojunctions through oxygen defect engineering

The development of efficient and stable photocatalysts holds vital importance in the fast and effective removal of toxic contaminants from wastewater. In this study, novel 1D/2D BiVO4-OV/NiMoO4 hybrid with enriched oxygen vacancies (BiVO4-OV/NiMoO4) were successfully synthesized by using one step hydrothermal synthesis route. Utilizing the p-n heterojunction and oxygen vacancies, the optimized BiVO4-OV/NiMoO4 composite exhibited exceptional photocatalytic efficiency, achieving a photocatalytic degradation efficiency of 92 % for rhodamine B (RhB) under visible light irradiation within 60 min. The apparent rate constant of value of optimized BiVO4-OV/NiMoO4 composite is 0.02864 min−1, exceeding those of BiVO4 and NiMoO4 by 4.4 times and 5.5 times, respectively. The photocatalytic mechanism and degradation pathways of RhB were investigated through active species trapping experiment. Remarkably, optimized BiVO4-OV/NiMoO4 hybrid demonstrated high stability and recyclability. This study on the development of highly efficient visible-light catalysts through synergistic defect and heterojunction engineering, offering a promising approach for organic pollutant degradation.

Liquid metal-embedded magnetic hydrogel beads as novel adsorbents for malachite green removal

Malachite green (MG) is widely used in aquaculture as a parasiticide. It has generated much concern due to its carcinogenesis, mutagenesis, chromosomal fractures, teratogenicity, and respiratory toxicity. Effective methods for removing MG from water or other media are highly needed. Here, liquid metal (LM) is embedded into the magnetic hydrogel to create magnetic LM hydrogel beads with high adsorption capacity. The morphology and physical properties of the LM-embedded magnetic hydrogel beads are characterized using scanning electron microscopy, optical microscopy, and texture analysis methods. The adsorption efficiency of malachite green was assessed using spectrophotometric analysis at a wavelength of 623 nm. The hardness of these hydrogel beads reached a maximum of 4610 g, and its adsorption capacity reached 10 mg/g. Under the optimal condition, 0.05 %wt LM embedded magnetic hydrogel could remove 100 % of MG. This highly efficient magnetic adsorbent for dye removal has considerable potential for rapidly separating toxic contaminants from aquatic animal tissues, providing a cost-effective and straightforward solution to reduce dye pollution in aquatic environments and food products.

Groundwater in Katowice - center of a large urban and deep coal mining area in Poland

The paper presents the groundwater resources of Katowice and the results of studies conducted to identify prospective areas in aquifers with sufficient water resources for the location of public water intakes. The city of Katowice is the capital of Upper Silesia, the largest urban-industrial area in Poland, the region with a highly developed hard coal mining and many other different industries covering almost the entire scope of the economy. Due to long term drainage of mines causing the depletion and deterioration of groundwater and surface water resources, the main municipal water intakes have been located outside Katowice. Most of the pumped mine water is discharged into surface waters, causing significant salinity of water and disallow its use for municipal or industrial purposes in Katowice. The water collection and supply system is very extensive and covers a significant part of the Silesian agglomeration which is why Katowice is supplied with water from surface water intakes located outside the city. According to older published materials, such as the Hydrogeological map of Poland, there were no aquifers in the city that could have been used to supply the city with drinking water, however recent studies have shown that groundwater in the Quaternary aquifers in the western part of the city can be used to supply the city with public water. Less productive, Quaternary aquifers in north-eastern parts of the city may constitute the basis for drinking water supply in emergency situations, when surface intakes cannot be used, such as toxic, radiological or viral contamination or damage to the water supply network eg. as a result of an earthquake or warfare.

Phytoremediation of contaminated urban soils spiked with heavy metals

Urban environments worldwide face toxic heavy metal pollution originating from industrial discharge, municipal waste disposal, vehicular emissions, and atmospheric deposition. Kazakhstan, experiencing accelerated economic growth and extensive mining activities, contends with widespread heavy metal contamination in its soil-plant-air-water ecosystems. This study explores the potential of hyperaccumulating plants for phytoremediation in urban soils of Kazakhstan contaminated with Pb, Cd, and Co. Twelve plant species, including Korean Mint (Lamiaceae), Ornamental Cabbage (Brassica oleracea), Ageratum (Ageratum houstonianum), Coneflower (Echinacea purpurea), Amaranth (Amaranthus Perfect and Amaranthus Emerald), Fescue (Festuca glauca), Burning Bush (Kochia scoparia), Marigold (Tagetes patula nana), White Cabbage (Brassica-Cavolo cappuccino BIANKO), Tepary Bean (Phaseolus acutifolius), and Rapeseed (Brassica napus), were evaluated for growth and biomass production in urban soils spiked with two maximum permissible addition (MPA) treatments of Pb, Co, and Cd. The selected plants demonstrated varied responses to heavy metal stress, with Marigold (8.4 g shoot biomass/plant), Korean mint (10.5 g shoot biomass/plant), Rapeseed (19.9 g/shoot biomass), and Tepary bean (25.9 g shoot biomass/plant) exhibiting resilience or tolerance to Pb, Co, and Cd stresses. The results highlight the significant potential of these plants for efficient phytoremediation, showcasing their unique abilities to absorb and accumulate specific metals. Marigold, particularly, displayed noteworthy Pb accumulation (40.3 mg/kg biomass), resulting in reduced residual Pb concentrations in the soil (74.7 mg/kg). Conversely, White cabbage and Amaranth showed limited efficiency in Cd extraction, while Rapeseed and Tepary bean emerged as promising candidates for Cd phytoremediation. This study emphasizes the critical role of tailored plant species selection in designing effective phytoremediation strategies for specific metal-contaminated urban sites. A comprehensive understanding of the dynamics of metal accumulation and residual concentrations is crucial for the development of sustainable and efficient environmental remediation approaches. Further research is warranted to explore the long-term effects of different plant species on soil metal concentrations, refining and optimizing phytoremediation methods for urban soils grappling with toxic heavy metal contamination.

Holistic insight into the viability of employing cerium(IV) sulphate to oxidise toxic contaminants in effluent from the coal gasification process: Optimisation studies

The coal gasification (CG) process, while beneficial for producing syngas, poses environmental risks due to the production of highly toxic wastewater containing high concentrations of polycyclic aromatic hydrocarbons (PAHs), phenolics, and cyanides. This study examines the oxidation of pollutants in wastewater from a simulated underground coal gasification (UCG) process, with initial pollutant levels of pH 1.8, total cyanides 21.00 mg/L, total phenols 61.95 mg/L, heavy metals 7.68 mg/L, PAHs 2459 μg/L, and dissolved organic carbon (DOC) 148.0 mg/L. Three oxidation systems (Ce(SO4)2·4H2O, Ce(SO4)2·4H2O + H2O2, and Fenton process with FeSO4 + H2O2) were used to remove pollutants from wastewater from the coal gasification process. In the first system, the oxidising agent was Ce4+ ions, while in the second and third systems, where hydrogen peroxide was added, the oxidising agents were hydroxyl radicals. Using central composite design and response surface methodology (CCD/RSM), the most favourable oxidation conditions were identified for Ce(SO4)2·4H2O (35 min, Ce4+:C molar ratio of 5:1, pH 2.5, temp. 40 °C). For the Ce(SO4)2·4H2O + H2O2 system DOC:Ce4+:H2O2 molar ratio of 1:2:10. Results showed significant reduction in pollutants: Ce(SO4)2·4H2O reduced PAHs, phenols, cyanides, DOC, and heavy metals by 99.40 %, 99.97 %, 97.67 %, 65.34 %, and 90.01 %, respectively; Ce(SO4)2·4H2O + H2O2 achieved reductions of 99.91 %, 99.66 %, 98.14 %, 76.35 %, and 81.45 %; and the Fenton process achieved reductions of 99.91 %, 99.95 %, 95.07 %, 56.49 %, and 89.33 %. An application of alternative oxidation processes (Ce(SO4)2·4H2O and Ce(SO4)2·4H2O + H2O2) is a viable option in removing toxic pollutants with simultaneously cerium recovery.

Synergistic biochar and Serratia marcescens tackle toxic metal contamination: A multifaceted machine learning approach

Metal contamination in soil poses environmental and health risks requiring effective remediation strategies. This study introduces an innovative approach of synergistically employing biochar and bacterial inoculum of Serratia marcescens to address toxic metal (TM) contamination. Physicochemical, enzymatic, and microbial analyses were conducted, employing integrated biomarker response (IBR) and machine-learning approaches for toxicity estimation. The combined application significantly reduced the Cd, Cr, and Pb concentrations by 71.6, 31.2, and 57.1%, respectively, while the Cu concentration increased by 85% in the individual Serratia marcescens treatment. Biochar enhanced microbial biomass by 33–44% after 25 days. Noteworthy physicochemical improvements included a 44.7% increase in organic content and a decrease in pH and electrical conductivity. The K⁺ and Ca2⁺ concentrations increased by 196.9 and 21.6%, respectively, while the Mg2⁺ content decreased by 86.4%. Network analysis revealed intricate relationships, displaying direct and indirect negative correlations between metals and soil physicochemical parameters. The IBR index values indicated effective mitigation of TM toxicity in Serratia marcescens and biochar with individual and combined treatments. Binary classification demonstrated high sensitivity (80.1%) and specificity (80.5%) in identifying TM-contaminated soil. These findings indicate significant biochar- and Serratia marcescens-induced impacts on toxic metal availability, physicochemical properties, and enzymatic activities in metal-contaminated soil, suggesting that blending soil with biochar and microorganisms is an effective remediation strategy.

CRISPR/Cas12a-Based Indirect Competitive Enzyme-Linked Immunosorbent Assay for Sensitive Detection of Ochratoxin A.

The high toxicity and widespread contamination of ochratoxin A (OTA) make it urgent to develop a sensitive method to detect trace OTA in complex food matrices. Herein, an indirect competitive enzyme-linked immunosorbent assay (icELISA)-based on the CRISPR/Cas12a system is described. DNA amplicons with multiple activation sequences of the CRISPR/Cas12a system were pre-prepared to improve detection sensitivity. In the absence of OTA, streptavidin-mediated biotinylated DNA amplicons were captured by the biotinylated secondary antibody on the microplate. The captured DNA amplicons activated the CRISPR/Cas12a system, which thereby effectively cleaved the reporter DNA, producing strong fluorescence. The presence of OTA led to a decrease in DNA amplicons on the microplate, resulting in a decrease in activated Cas12a and ultimately a drop in fluorescence intensity. OTA in food matrices at nanogram per milliliter levels can be detected. Therefore, the new method has great potential in monitoring OTA.

Pharmacological assessment of delphinidin in counteracting polystyrene microplastic induced renal dysfunction in rats

Polystyrene microplastics (PSMP) are toxic environmental contaminants which can damage various body organs including kidneys. Delphinidin (DEL) is a potential anthocyanidin flavonoid with significant pharmacological benefits. This research was conducted to analyze the protective effect of DEL to avert PSMP prompted renal dysfunction. Rats (n = 24) were divided into 4 separate groups: Control, PSMP (0.01 mgkg−1), PSMP (0.01 mgkg−1) + DEL (25 mgkg−1) and only DEL (25 mgkg−1). Our results showed that PSMP exposure reduced the expressions of Nrf-2 and antioxidant genes while increasing the expression of Keap1. Besides, PSMP intoxication escalated the level of kidney injury markers (urea, KIM-1, creatinine and NGAL) while inducing substantial reduction in the levels of creatinine clearance. Moreover, PSMP significantly reduced the levels of GSH, GST, SOD, HO-1, CAT, GSR, GPx while escalating MDA and ROS. Conversely, inflammatory biomarkers including IL-1β, TNF-α, NF-kB, IL-6 and COX-2 activity were increased due to PSMP intoxication. Our results showed that PSMP administration increased the expressions of Bax and caspase-3 while decreasing the expression of Bcl-2. However, DEL treatment significantly restored the PSMP-induced renal impairments. Therefore, it is suggested that DEL could be used as a therapeutic compound to alleviate PSMP-induced kidney damage in rats, possibly due to its strong pharmacological properties.

Dried Anaerobic Digestate from Slaughterhouse By-products: Emerging Cues for a Bio-Based Fertilization

AbstractThe slaughterhouse and meat industry are worldwide rapidly growing and produce billions of tonnes of organic wastes annually. These materials can be used to produce biogas through anaerobic digestion and the resulting digestate represents a potential source of organic carbon and nutrients that could be applied to the soil as organic fertilizer. The present work aims to assess the fertilizing potential of a dried anaerobic digestate (DD) produced from beef slaughtering waste. DD was characterized at the physic-chemical level, particularly focusing on macro- and micronutrient contents, potentially toxic element and organic contaminants. Then, a short-term soil incubation experiment was performed on two different soils. After the incubation, DD released 10–26% of their total nitrogen (N) and 13–16% of total phosphorus (P), depending on the soils that had different characteristics and responded differently to the treatments. However, DD had positive effects on the principal soil fertility indicators, such as chitinase and phosphatases, stimulating the microbial activity and therefore exploiting a fertilizing potential as well as the other organic fertilizers tested. Moreover, DD had minor effects on soil extractable carbon (Cext) suggesting the presence of recalcitrant C forms in spite of soluble C, indicating a higher stability of slaughterhouse by-products after anaerobic digestion in respect to the other organic fertilizers. The results obtained in this work raise the concrete possibility use DD as a bio-based fertilizer. Graphical Abstract

Assessment of potentially toxic element contamination in commercially harvested invertebrates from the Beibu Gulf, China

Marine pollutants, especially potentially toxic elements (PTEs), increasingly threaten the ecological environment and fishery resources of the Beibu Gulf due to their bioaccumulative nature, toxicity, and persistence. However, the occurrences of multiple PTEs in marine invertebrates within this region remains unclear. Hence, a total of 18 species of commercially harvested invertebrates (shrimp, crab, cephalopod, shellfish, and sea cucumber) were collected from the Beibu Gulf, and the concentrations of nine important PTEs (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were examined. Subsequent stable isotope analysis for δ13C and δ15N facilitated investigations into biomagnification and human health risk assessment. The results showed that, except for As, the concentrations of the PTEs in the invertebrates were below the national safety limits. Furthermore, significant positive correlations were found between trophic levels (TLs) and log-transformed concentrations of As (P < 0.001, R2 = 0.20) and Cr (P < 0.001, R2 = 0.13), indicating biomagnification of these two metals across trophic positions among species. Finally, the human health risk assessment revealed that the consumption of cephalopod, shellfish, and sea cucumber poses a higher risk of adverse effects compared to shrimp and crab.

The reproductive geography of miscarriages. Social identities, places, and reproductive inequalities

Increasing epidemiological evidence demonstrates the correlation between toxic contamination and miscarriages, and the disproportionate exposure of marginalised and racialised groups to environmental burdens. Yet, the debate on environmental reproductive health is still largely underpinned by a reductionist biomedical understanding of the health-place relationship that overlooks the interplay between social identities and places. In this article, I argue that understanding the role that places play in shaping reproductive inequalities, beyond the simplistic recognition of the environment as a factor of risk, is important to design a more inclusive reproductive health agenda that addresses the multiple scales across which reproductive inequalities unfold. These scales span from everyday experiences of reproduction to state-level models of reproductive governance. Drawing on 13 months of fieldwork in coca-farming territories in the Bajo Cauca region (Colombia), the aim of this paper is to conceptualise the reproductive geographies of miscarriages related to toxic contamination. This article contributes to debates on reproductive inequalities by discussing the complex and dynamic relationship between social identities and places, and theorising the spatiality of miscarriages.

Alternative agar substitutes for culturing unculturable microorganisms.

Gelling agents are necessary for the preparation of solid or semisolid media. For more than a hundred years, agar has been the primary gelling agent. However, a substantial body of evidence has accumulated suggesting that agar-based media inhibit the growth of many microbial species through the generation of reactive oxygen species (ROS), toxic organic contaminants, or competitive exclusion effects. In this review we have compiled the largest amount of data to date on the use of various gelling agents in microbial isolation and cultivation, with the particular emphasis on rare microbe isolation cases. Our analysis suggested that microbial-derived compounds (especially gellan gum), as gelling agents, are superior to agar in their ability to isolate and maintain either new or known microbial species. We analyzed the reasons behind this success and concluded that there are phylum-level differences in microbial responses to the changes in conditions from natural to the laboratory conditions (with respect to gelling agent usage). Consequently, we hypothesize that at least partial success of microbial-derived gelling agents lies in the recreation of the natural microenvironment conditions (which we address as the "familiarity of conditions" hypothesis). Finally, we present a list of recommendations and suggestions for further microbial ecology studies.

Perspectives on the Toxic Effects of Micro- and Nanoplastics on the Environment: A Bibliometric Analysis of the 2014 to 2023 Period.

Over the past decade, micro- and nanoplastics (MNPs) have garnered significant attention due to their frequent detection in and potential toxic effects on the environment and organisms, making them a serious threat to human health. To comprehensively understand the research on MNPs' toxicity, we employed the R language-based Bibliometrix toolkit (version 4.3.0), VOSviewer (version 1.6.11) and CiteSpace (version 6.3.R1) to perform statistical and visual analyses of 3541 articles pertaining to MNPs' toxicity between 2014 and 2023, which were retrieved from the Web of Science Core Collection (WOSCC) database. The analysis revealed that research related to MNPs' toxicity has experienced a rapid increase in recent years. China's particularly prominent influence in the field of MNPs' toxicity is evidenced by its academic exchanges and the establishment of a mature cooperation system with other countries (regions), such as the USA and Germany. Studies related to MNPs' toxicity are primarily published in leading journals, including the Science of the Total Environment, Environmental Pollution, and the Journal of Hazardous Materials. The Chinese Academy of Sciences was identified as the leading institution in terms of research on MNPs' toxicity, contributing 203 papers to the total number of studies published. Keyword co-occurrence and burst analyses indicated that the current research on MNPs' toxicity mainly focuses on the toxic effects of MNPs on aquatic organisms, the combined toxicity of MNPs and other contaminants, and the toxic effects and mechanisms of MNPs. Future research should integrate computational toxicology and toxicomics to enhance our understanding of MNPs' toxicity mechanisms and assess the potential health risks posed by atmospheric MNPs.

Mesoporous PtIr alloy single-particle: A novel SECM-tip for in situ monitoring NO of single-cell

As a vital factor in cell metabolism, nitric oxide (NO) is associated with nitrosative stress and subsequent inflammations and diseases. In situ, real-time NO monitoring is challenging due to its relative trace concentration and fast diffusion in cell. Scanning electrochemical microscopy (SECM) is suited uniquely for single-cell analysis, and its electrochemical response to targets can be further enhanced by improving the interfacial properties of its tip. Here, an ultramicroelectrodes (UMEs) modification strategy based on bimetallic single-particle was proposed for the first time. This mesoporous platinum/iridium alloy single-particle (mPtIr SP) interface using micelle-assisted electrodeposition was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). And the nucleation kinetic progress which can be defined as "oil-in-water-like" electrodeposition was discussed in detail. The high sensitivity (203.86 μA/μM·cm2) and good selectivity for NO detection benefits from the high catalysis of the PtIr alloy and the high mass transfer properties of the porous interface. In particular, this novel UME can real-time monitor NO release from a single MCF-7 cell stimulated by perfluorooctanoic acid (PFOA), providing new ideas for contaminant toxicity assessment, health diagnostics, and disease treatment.

Uranium Speciation and Mobilization in Thawing Permafrost.

Uranium is a toxic and pervasive geogenic contaminant often associated with organic matter. Its abundance and speciation in organic-rich permafrost soils are unknown, thereby limiting our ability to assess risks associated with uranium mobilization during permafrost thaw. In this study, we assessed uranium speciation in permafrost soil and porewater liberated during thaw using active-layer and permafrost samples from a study area in Yukon, Canada where elevated uranium concentrations occur in bedrock and groundwater. Permafrost contained 1.1-28 wt % organic carbon and elevated uranium (range 7.6-1040 μg g-1, median 25 μg g-1) relative to local bedrock. The highest soil uranium concentrations were encountered in catchments hosting uranium-enriched bedrock and correlated positively with soil organic carbon. X-ray absorption spectroscopy, micro-X-ray fluorescence, and electron microscopy analyses revealed that solid-phase uranium predominantly occurs as uranium(VI) associated with soil organic matter. Extended X-ray absorption fine structure (EXAFS) analyses suggested the presence of uranium(VI) coordinated with carbon, consistent with bidentate-mononuclear uranyl complexation on carboxyl groups. Permafrost thaw produced circumneutral pH porewater (pH 6.2-7.5) with elevated dissolved uranium (0.5-203 μg L-1). Geochemical modeling indicated that calcium-uranyl-carbonate complexes dominated the dissolved uranium speciation. This study highlights that permafrost soil can mobilize uranium upon thaw and that uranium fate is linked to dynamic biogeochemical reactions involving organic carbon and groundwater chemistry.

Real-time SERS sensing of highly toxic seawater contaminants using plasmonic silver assembled pyramidal/nanowire heterostructures

Hierarchically oriented plasmonic nanostructures have attracted an advanced molecular sensing platform for multifaceted applications. In the present work, we have attempted to fabricate ultrasensitive and cost-effective pyramidal/nanowire hetero arrays, hosted with silver nanoparticles for the effective surface-enhanced Raman spectroscopy (SERS) assisted detection of toxic water contaminants. Three-dimensionally oriented pyramidal/nanowire hetero arrays with enhanced surface area were fabricated by combining wet etching and metal-assisted chemical etching techniques. The regulation of structural features was achieved by controlling the process parameters during fabrication. Particularly, the evolution of morphological properties of the hybrid sensor was investigated in terms of nanowire aspect ratio and further analyzed in terms of SERS properties. The hetero arrays exhibited significant enhancement in Raman signal for sensing organic pollutants. Moreover, these hetero arrays with a nanowire length of ∼1 µm exhibited the highest signal enhancement. Further, the excellent reproducibility and reusability characteristics were also demonstrated for the fabricated sensors. Different cationic and anionic organic pollutants were employed for efficacy studies which showed detection limits ranging from femtomolar to picomolar levels. Finally, the real-time sensing of organic contaminants such as aniline was also investigated from seawater with an estimated enhancement factor of 8 × 108, indicating that as-fabricated hetero arrays can perform as outstanding SERS sensors for environmental remediation applications.

Silver and g-C3N4 co-modified biochar (Ag-CN@BC) for enhancing photocatalytic/PDS degradation of BPA: Role of carrier and photoelectric mechanism

Photocatalytic property of nano Ag is weak and its enhancement is important to enlarge its application. Herein, a novel strategy of constructing silver g-C3N4 biochar composite (Ag-CN@BC) as photocatalyst is developed and its photocatalytic degradation of bisphenol A (BPA) coupled with peroxydisulfate (PDS) oxidation process is characterized. Characterization result showed that silver was evenly embedded into the g-C3N4 structure of the nitrogen atoms format, impeding agglomeration of Ag by distributing stably on biochar. In optimum condition, BPA of 10 mg/L could be degraded completely at pH of 9.0 with a 0.5 g/L photocatalyst, 2 mM PDS in Ag-CN@BC-2 (Ag/melamine molar ratio of 0.5)/PDS system (99.2%, k = 4.601 h−1). Ag-CN@BC shows superior mineralization ratio in degrading BPA to CO₂ and H₂O via active radical way, including holes (h⁺), superoxide radicals (•O2⁻), sulfate radicals (SO4•⁻), and hydroxyl radicals (•OH). Proper amount of silver can be dispersed effectively by gC3N4, which is responsible for improving the visible-light absorbing capability and accelerate charge transfer during activation of PDS for BPA degradation, while biochar as carrier in the composite is supposed to enhance the photoelectric degradation of BPA by reducing the band gap and increasing the photocurrent of Ag-CN@BC catalyst. Ag-CN@BC exhibits excellent catalyst stability and photocatalytic activity for treatment of toxic organic contaminants in the environment.

Unlocking solar energy's potential: Dual photocatalytic activities of g-C3N4/Sb2S3 for hydrogen evolution and tetracycline degradation in sunlight

This study focuses on developing a g-C3N4/Sb2S3 heterojunction photocatalyst with different g-C3N4 to Sb2S3 weight ratios (1:1, 1:3, and 3:1) for degrading tetracycline (TC) pollutants. The 1:3 ratio (13 GS) exhibited optimal photocatalytic performance, achieving 99% TC degradation under sunlight within 120 min, compared to 78.4% under visible light and 38% under UV light. The 13 GS catalyst demonstrated strong reusability, maintaining 80% degradation efficiency after six cycles. Scavenger experiments identified hydroxyl radicals as crucial for TC degradation, with DMSO reducing activity by 30%. The photocatalyst also showed high hydrogen production with an apparent quantum efficiency (AQE) of 19.8% under standard conditions, and improved AQE in acidic (23%) and basic (22.7%) conditions, and with CH3OH (23.2%). This g-C3N4/Sb2S3 heterojunction offers a promising solution for degrading toxic contaminants and has the potential for solar-powered applications.