Environmental Chemistry Letters最新文献

The access to drinkable water is a critical challenge in the context of the rising urbanization and industrialization, calling for advanced technologies to clean contaminated waters and wastewater. Here we review the use of metal oxides biochar composites to treat pollution by hevay metals and dyes. We focus on the synthesis of metal oxide nanobiochar; the treatment of pollution by mercury, lead, methylene blue and methyl orange; life cycle analysis; and techno-economical assessment. Metal oxide nanoparticles can act as photocatalysts to allow for the complete mineralization of organic pollutants. For instance, the doping of tin oxide nanoparticles into biochar surface degraded 99.5% of methylene blue dye after 105 min. Ball-milled magnetic nanobiochar achieves 99% mercury removal in 720 min. The presence of biochar enhanced the uptake of contaminants on nanoparticles and facilitated the photocatalytic reaction

Airborne microplastics are a type of suspended particulate matter less than 100 µm in size. They have drawn attention recently due to their potential impact on human health and the environment. However, knowledge on airborne microplastics in forest and their interaction with plant leaves is limited. Here, we analyzed microplastics on konara oak leaves collected at a small forest in Tokyo. Leaves were water-washed to yield a first extract, sonicated in water to yield a second extract and then extracted with 10%w potassium hydroxide to yield a third extract. We employed micro-Fourier transform infrared spectroscopy with attenuated total reflection imaging to analyze microplastics, identifying polymer materials and quantifying their concentration. Results show that the average number of microplastics in leaf were 0.01 piece/cm² in the water extract (7.6%), 0.05 piece/cm² by sonication (38.4%), and 0.07 piece/cm² in the potassium hydroxide extract (53.8%). Microscopic data reveal that potassium hydroxide extraction allows to remove epicuticular waxes including adhering substances. These findings highlight the need to use a strong basic reagent, potassium hydroxide, to extract most airborne microplastics in leaf. The findings also suggest that canopy leaves could be a long-term sink for airborne microplastics, rather than merely temporary accumulators.

Per- and polyfluoroalkyl substances (PFAS) are being increasingly measured in water and wastewater due to emerging toxicity concerns and strict regulatory limits. Previous studies have filtered water samples to remove suspended solids before PFAS analysis. However, filtration may introduce negative bias to measured PFAS concentrations. Using a well-controlled syringe pump assembly, we evaluated retention of six perfluoroalkyl carboxylates, three perfluoroalkyl sulfonates, one fluorotelomer sulfonate, and two perfluorooctane sulfonamides by glass-fiber, glass-fiber cellulose acetate, nylon, polyethersulfone, polypropylene, polyvinylidene fluoride/ difluoride, and surfactant-free cellulose acetate filters. The impacts of water quality and operational parameters were also investigated for select filter types. We found that PFAS were retained on all filters, with the glass-fiber cellulose acetate filters demonstrating the lowest retention. For all filters, PFAS retention was linearly related to chain length and hydrophobicity above certain thresholds (i.e., log D higher than 1.5). Importantly, more PFAS were retained at low filtrate volumes, and ~ 30 mL filtrate was required before the retention efficiencies stabilized. Solution pH only affected the retention of perfluorooctane sulfonamides. Pore size (i.e., 0.20, 0.45, 0.70 µm), filtration rate (i.e., 0.5, 1.0 mL min⁻¹), and PFAS concentration (i.e., 10, 100 µg L⁻¹), did not exert major influences on PFAS retention. The presence of dissolved organic matter improved PFAS permeation. Based on the reported results, filtration introduces bias and is not recommended for sample pretreatment.

Catalytic biodiesel production with bases can be achieved under relatively mild conditions. However, the basicity of solid alkali catalysts originates usually from electron-rich atoms such as oxygen and nitrogen, rather than electron-deficient metal species. This typically induces aggregation and leaching of active sites, and difficulty in recycling. Here we synthesized a photothermal catalyst made of stable and uniformly dispersed graphene-like biomaterial anchored neighboring potassium single atoms. The production of biodiesel from various acidic oils over this catalyst was evaluated by life cycle assessment and cost analysis. Infrared thermal imaging and finite element simulations were used to study the light-induced self-heating process. We further studied the alkaline behavior of neighboring potassium single atoms by carbon dioxide chemisorption and quantum calculations. Results show biodiesel yield of 99.6% at room temperature, which is explained by a good local photothermal effect at the solar interface and the presence of superalkali sites in the atomic potassium-containing biomaterial. The global warming potential measured for this system resulted in a net negative CO₂ emission of −10.8 kg CO₂eq/kg. The photothermal catalyst can be recycled with almost no decline in reactivity.

The consumption of renewable energy should increase by 300% by 2050 compared to 2010 due to the rising demand for green electricity, stringent government mandates on low-carbon fuels, and competitive biofuel production costs, thus calling for advanced methods of energy production. Here we review the use of activated carbon, a highly porous graphitic form of carbon, as catalyst and electrode for for energy production and storage. The article focuses on synthesis of activated carbon, hydrogen production and storage, biodiesel production, energy recovery, and the use of machine learning. The textural properties and surface chemistry of activated carbon can be engineered using acid and base treatments, hetero-atom doping, and optimization of the activation conditions to improve the efficiency of renewable energy production and storage. Machine learning allows to optimize the synthesis of catalysts, electrodes and bioproducts, with benefits to the biorefinery industries.

A biofilm is a layer of microbes that have aggregated to form a colony. The colony attaches to a surface with a slime layer which protects the microorganisms, promoting their growth and survival. Biofilms occur in various environments such as soils, sediments, wastewater, water pipelines, water purifying systems, cooling water systems, medical devices, archaeological monuments, marine vessels, and hospitals. Biofilms may induce adverse effects such as fostering drug-resistant strains. Here, we review biofilms with focus on their formation, occurrence in water systems, impact, microbial interactions, and characterization methods. Communication includes cell-to-cell interactions by quorum sensing, interactions mediated by flagella, gene, and signaling molecules, and interactions mediated by extracellular polymeric substances. Characterization methods comprise surface-enhanced Raman scattering spectroscopy, confocal laser scanning microscopy, scanning electron microscopy, fluorescence microscopy, sensors, and metagenomics analysis.

The contamination of seafood by heavy metals is a rising health issue in the context of pollution caused by increasing industrialization and urbanization. Crustaceans are particularly susceptible to heavy metal pollution in aquatic ecosystems due to their benthic and sedimentary lifestyle. Here we review crustaceans contamination by heavy metals with a focus on metal sources and dynamics, interaction of metals with other pollutants, metal analysis, bioconcentration and bioaccumulation, toxicity, and strategies to control metals. We observed that crustaceans tend to accumulate more heavy metals than other aquatic animals. Consequently, in certain regions of the world, consuming crustaceans as food may potentially threaten human health. The bioavailability, transport, and interaction of heavy metals with other pollutants depend on various factors, potentially leading to differential toxicity. Heavy metals induce multiple toxic effects on crustaceans, including metabolic dysfunction, genotoxic effects, respiratory impairments, DNA damage, sperm mobility, and quantity, and these poisonous effects will intensify with prolonged exposure time and increasing concentration. The concentration of heavy metals in crustacean samples is usually determined by inductively coupled plasma optical emission spectrometry and mass spectrometry. Approaches to reducing this potential threat include proper industrial wastewater treatment and using low-cost adsorbent materials in aquaculture.

Many products contain silver nanoparticles, which are adsorbed by living organisms and then go through biological barriers. In particular, penetration of silver nanoparticles through the placental barrier is likely to damage the offspring. Here, we review hazards of silver nanoparticles with focus on exposure during pregnancy, toxicokinetics at maternal and fetal layers, ex vivo and in vivo placenta transfer models, and factors affecting the transfer. Exposure occurs by oral uptake, inhalation, dermal contact, and systemic administration. Toxicokinetics include absorption, distribution in tissues, metabolism and excretion. The accumulation efficiency is primarily influenced by the mode of exposure. Injection exhibits the highest bioavailability, followed by inhalation and oral uptake. Particles within the range of tens of nanometers are capable of crossing the placenta, according to an ex vivo placental perfusion model. In contrast, larger particles in the range of hundreds of nanometers are expelled outside. Due to the size restriction of the trophoblast channel, which typically ranges from 15 to 25 nm, it is possible for silver nanoparticles with an average size of around 20 nm to passively enter the placenta through the pericellular pathway, such as diffusion. On the other hand, larger silver nanoparticles may be delivered to the placenta through endocytosis, which can occur via phagocytosis, receptor-mediated or independent mechanisms.

Plastic pollution is becoming a major health issue due to the recent discovery of microplastics and nanoplastics in living organisms and the environment, calling for advanced technologies to remove plastic waste. Here we review enzymes that degrade plastics with focus on plastic properties, protein engineering and polymers such as poly(ethylene terephthalate), poly(butylene adipate-co-terephthalate), poly(lactic acid), polyamide and polyurethane. The mechanism of action of natural and engineered enzymes has been probed by experimental and computation approaches. The performance of polyester-degrading enzymes has been improved via directed evolution, structure-guided rational design and machine learning-aided strategies. The improved enzymes display higher stability at elevated temperatures, and tailored substrate-binding sites.