Environmental Chemistry Letters最新文献

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.

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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%.

Germanium is a critical element used in optical materials, electronic semiconductors, optical fibers, catalysts, sensors, medicine and health. Worldwide, 36% of the annual refined germanium comes from lead zinc sulfide ores, and more than 90% of germanium enters the zinc smelting system as an associated impurity with the zinc roasting sand. Here we review the recovery of germanium in zinc smelting processes, with focus on germanium reserves, applications and demand, recovery methods and extraction mechanisms. Recovery methods include tannin precipitation, ion exchange and solvent extraction. Extraction mechanisms are described for acidic, alkaline, neutral and synergistic extractions.

The conversion of biomethanol into olefins is a sustainable alternative to fossil fuels, yet this reaction is limited by the deactivation of the silicoaluminophosphate zeolite catalysts due to its microporosity, which promotes coke deposition. Here we synthesized a fibrous silica-wrapped silicoaluminophosphate catalyst by microemulsion and seed-assisted hydrothermal method. This catalyst was characterized by X-ray diffractometer, Fourier transform infrared spectroscopy, nitrogen physisorption, field emission scanning electron microscopy, transmission electron microscopy, and ammonia temperature-programmed desorption. The catalytic performance was evaluated from 300 to 500 °C, followed by a stability test conducted at 500 °C for 30 h. Coke deposition on spent catalysts was analyzed using thermal gravimetric analysis, oxygen temperature-programmed oxidation, ultraviolet–visible, and Raman spectroscopy. Results show a 54% extension of the catalyst lifetime, and a 31.4%w reduction in coke formation. These findings are explained by the fibrous silica wrapping that creates a surplus mesoporosity beyond conventional hierarchical structure, enabling improved accessibility, reduced diffusion resistance, and suppressed coke formation.