Environmental Chemistry Letters最新文献

Remediation of metal-contaminated soils by aqueous washing is actually done using synthetic surfactants, calling for safer alternatives such as biosurfactants. Here we tested coffee-based humic substances extracted from various composts for soil washing of agricultural, industrial and urban soils contaminated by heavy metals. Molecular-level characterization of humic substances was done by ¹³C-nuclear magnetic resonance and thermochemolysis gas chromatography-mass spectrometry. Following washing, we measured heavy metals displacement into humic substance suprastructures by inductively coupled plasma mass spectrometry. Humic substance molecular changes were observed by ultrahigh resolution Orbitrap mass spectrometry. Soil toxicity was studied using the Microtox® Aliivibrio fischeri bioluminescence system. Results show that metal removal reached 90% for antimony, 15% for copper, and 13% for zinc. Moreover, toxicity was reduced by up to 62% for industrial soils, 50% for urban soils, and 46% for agricultural soils. The metal removal could be explained by chelation with humic pentacyclic terpenes.

The use of fossil fuels in the aviation sector is accelerating global warming by emitting carbon dioxide into the atmosphere, calling for carbon neutral jet fuels. Unlike road transport, which is transitioning to electrification, aviation requires high-energy–density fuels, making liquid alternatives essential. Here we review the production of jet biofuels with emphasis on current production technologies, microbial engineering for lipid synthesis, catalytic conversion of lipids, and economic and life cycle assessment aspects. Microbial lipids, including free fatty acids, can be produced from various carbon sources such as sugars, lignocellulose, methane, methanol, and formate. Catalytic upgrading of lipids can be achieved by hydroprocessing, hydrodeoxygenation, hydrocracking, and hydroisomerization. Metabolic engineering strategies to enhance lipid biosynthesis include increasing the precursor supply, repressing β-oxidation, controlling fatty acid chain length, and applying systems-level optimization using flux balancing, biosensor-guided regulation, and evolutionary engineering. These strategies have enabled the production of 98.9 g lipids and 50 g free fatty acids per liter. Pichia pastoris employing methanol as a substrate can produce up to 23 g/L of free fatty acids. Catalytic upgrading via hydrodeoxygenation and hydrocracking achieves conversion efficiencies over 90% and jet fuel selectivity above 70%. Techno-economic and life cycle assessments indicate that microbial oil-based sustainable aviation fuels could be cost-competitive and environmentally favorable.

Vacuum ultraviolet light produces reactive species that can degrade aqueous organic pollutants. Here we review the methods for measuring the molar absorption coefficients at 185 nm, the absorption coefficients of water components, and the effect of wavelength, water pH, temperature, and concentration. We present absorption coefficients of water, dissolved gases, ions, organic compounds, oxidants and reductants. We observe that absorption of vacuum ultraviolet photons by trace-level pollutants is negligible. By contrast, absorption of vacuum ultraviolet photons by inorganic compounds such as nitrate and chloride, and by oxidants or reductants, e.g. chlorine and sulfite, are pronounced and often overlooked. Increasing the temperature favors water cleavage but disfavors vacuum ultraviolet absorption by other substances, hence diminishing direct photolysis. Unexpectedly, the molar absorption coefficients of many compounds such as potassium exhibit high variability among published reports.

Methylene blue is a textile dye widely used as a reference probe in laboratory studies to set optimal removal conditions, yet reported physical properties of methylene blue are often erroneous. Here we review methylene blue properties with emphasis on erroneous or confusing literature data. We present molecular, biological, water solubility, spectroscopic, physicochemical and degradation properties, with focus on medicinal effects, lipophilicity, sorption, X-Ray diffraction, computed molecular structure, specific surface area, ultraviolet–visible, molar absorptivity, solvatochromism, pH, infrared, self-association, acid/base and redox behaviours, photocatalytic degradation, oxidative degradation, and biodegradation. 

Antimicrobial resistance is a major global issue endangering human, animal, and environmental health, calling for alternative antibiotics. Here, we review antimicrobial peptides with focus on their history, properties, medicinal use, clinical applications, and environmental fate. Antimicrobial peptides include glycopeptides, daptomycin, polymyxins, gramicidin, tyrocidine, and bacitracin. We present their environmental degradation pathways such as hydrolysis, photolysis, biodegradation, and adsorption, and their potential toxicity. Although antimicrobial peptides are increasingly used, their environmental occurrence and transformation products remain poorly known. In particular, emission sources such as wastewater treatment plants are poorly documented, and the influence of antimicrobial peptides on environmental antimicrobial resistance is still largely unknown.

Graphical abstract

The rapid climate warming caused partly by rising carbon dioxide levels calls for efficient methods to capture and convert carbon dioxide into energy and chemicals. Here, we review microalgal carbon dioxide capture with focus on photosynthesis, chemical adsorbents and catalysts, factors controlling carbon sequestration, cultivation systems, artificial intelligence and modeling, and applications. Carbon sequestration is controlled by feed gas composition and flow rate, temperature, pH, light, humidity, dissolved oxygen, shear stress, nutrients, and species, e.g., green algae and cyanobacteria. Microalgal biomass can be converted into biofuels, pharmaceuticals, biopolymers, and food.

Large quantities of spent catalysts containing strategic metals such as molybdenum, nickel, cobalt, and vanadium, are lost after hydrodesulfurization of petroleum. Here, we review the recycling of those metals using bacteria and fungi. We analyze bioleaching approaches, utilizing both chemoautotrophic and heterotrophic microorganisms, and examine how various operational parameters influence the extraction process. The formation of soluble species in the metabolic lixiviant derived from high-sulfur feedstocks creates optimal conditions for the activity of sulfur-oxidizing microorganisms, such as Acidithiobacillus thiooxidans. In contrast, bioleaching with Penicillium simplicissimum at a pH range of 4–7 promotes the formation of stable anionic molybdate, which is advantageous for the subsequent recovery process.

Current issues of pollution, energy shortage, and pollutant detection are calling for the development of advanced materials. Here, we review boron nitride nanomaterials with focus on synthesis, functionalization, and application in environmental remediation, energy production and storage, and chemical sensing. Nanomaterials synthesis is done by ball‐milling or acoustic cavitation‐assisted exfoliation, hard and soft template methods, calcination, hydro‐ and solvothermal methods, chemical vapor deposition, arc discharge, laser ablation, microwave, carbothermal reduction, coprecipitation, and electrospinning. Water pollutants are removed by adsorption or by photocatalysis using nanomaterials. Nanomaterials are used for hydrogen production and storage, and for sensing of pollutants and gases. Electrospinning and non‐template methods produce materials with high surface areas of 0.7–1,900 m²/g, and are cost‐effective and scalable. Pollutant removal efficiency ranges from 15 to 2,989 mg/g for cadmium, 20 to 808 mg/g for copper, 31 to 1,030 mg/g for methylene blue, 60 to 794 mg/g for crystal violet, 75 to 82% for ciprofloxacin, and 80 to 100% for tetracycline. Hydrogen generation reaches 31 mmol/g per hour, and hydrogen storage 7.7 wt%. Sensors sensitivity is 0.08 µM for ascorbic acid, and 0.15 pg/mL for concanavalin A.

Worldwide plastic pollution is a major heath and climate issue requiring the development of advanced recycling methods. Photoreforming is an emerging technique that use solar energy and catalysts to transform plastic waste into fuels, chemicals and materials. Here we review plastic photoreforming with focus on reaction mechanism, photocatalysts, and performance optimization. Photocatalysts include homogeneous and heterogeneous organic and inorganic compounds. Photocatalysts influence the reaction efficiency based on their morphology, structure and physicochemical properties. Homogeneous catalysts are more active, yet more expensive and difficult to separate. In contrast, heterogeneous catalysts are easily recovered and recycled.

Ammonia is a major chemical that plays vital roles in food supply and energy storage. The electrochemical synthesis of ammonia induces less greenhouse gas emissions and fossil fuel dependence than the traditional Haber–Bosch process. Here we review the electrocatalytic synthesis of ammonia with focus on mechanisms, transition metal catalysts, and economic aspects. Ammonia is synthesized by reduction of dinitrogen, nitrate, or nitric oxide. Catalysts mainly comprise copper-, iron-, and cobalt-based compounds, with recent research focusing on bimetallic and trimetallic catalysts, single-atom catalysts, three-dimensional nanostructures, and sulfides/phosphides. Copper-based catalysts appear as the most active due to their unique electronic configuration. Catalyst design is optimized by calculation of the Gibbs free energy and the adsorption energy. The common mechanisms involved in electrocatalytic ammonia (NH₃) synthesis are dissociative and associative pathways. Strategies for enhancing the Faraday efficiency and ammonia yield include structural optimization, facet engineering, vacancy engineering, and single-atom construction. The cost of electrocatalytic ammonia synthesis becomes competitive with the Haber–Bosch processes at an electricity price below $0.024 per KW and a Faraday efficiency higher than 80%.