Environmental Chemistry Letters最新文献

Neonicotinoids represent 25% of the insecticidal market and are essential for crop production, yet traditional neonicotinoids are toxic to most pollinators, which are also essential for food production. This issue may be addressed by the use of some chiral neonicotinoid isomers, which are much less toxic. Here, we review the chiral neonicotinoids dinotefuran, sulfoxaflor, cycloxaprid, and paichongding, with focus on their chiral characteristics, configuration stability, biological activity, ecological toxicology, and environmental fate. Isomeric separation of chiral neonicotinoids can be achieved by chromatography. The dinotefuran R isomer is less toxic than the S isomer to honeybees and earthworms by a factor of 2.7–145.9, with similar control efficiency of common agricultural pests. The insecticidal activity of (5R,7S)-paichongding are up to 20.1 times higher than that of other isomers, and it is absorbed fastest by crop roots and tends to be preferentially degraded and mineralized in soils. Therefore, formulations containing R-dinotefuran or (5R,7S)-paichongding could decrease ecological damage without compromising food production. On the other hand, it has not been possible to synthesize chiral isomers of sulfoxaflor and cycloxaprid, owing to the instability of their monomers in polar solvents.

Water contamination by microbial pathogens is a major health issue, yet the efficiency of traditional water disinfection methods is limited. Disinfection is classically attributed to reactive oxygen species, but here we hypothesize that membrane electroporation could also contribute. We developed a hydrodynamic cavitation discharge plasma fore water treatment setup, then evaluated its performance using Escherichia coli. We studied the effect of pulse frequency, pulse duration, and total treatment time. Results show 95% disinfection rate at a pulse frequency of 6 kHz and a duration of 7 μs. The efficiency increased with the total treatment time, suggesting the involvement of reactive oxygen species. A theoretical calculation suggests that the disinfection mechanism involves electroporation of cell membranes, in addition to the role of reactive oxygen species.

Mangroves are essential ecosystems for coastal protection, carbon sequestration, biodiversity, and food production. In particular, mud crabs, with an annual global landing of over 100,000 metric tons, are crucial for the economic livelihoods and food security of millions of small-scale fishers in Southeast Asia. Here, we review the impact of pollutants on mud crab populations in mangrove ecosystems, with emphasis on pollutant sources, toxic effects on crabs, and remediation using microbes and biochar. Pollutants include microplastics, per- and polyfluoroalkyl substances, pesticides, polycyclic aromatic hydrocarbons, and heavy metals. Pollution originates from agricultural runoff, industrial discharges, mining activities, urbanization, and domestic waste. We present the use of biochar for pollutant remediation and enhancing carbon sequestration. We observe that heavy metals, pesticides, and microplastics induce oxidative stress, disrupt antioxidant defense mechanisms, and impair the growth, reproduction, and survival rates of mud crabs. Microbial bioremediation can remove more than 90% of polycyclic aromatic hydrocarbons. Biochar application reduces by 87% the bioavailability of heavy metal in contaminated soils.

The current global greenhouse gas emissions have increased by over 90% since 1860 primarily due to our overreliance on fossil fuels, petrochemicals and their derivatives. Production of petrochemical plastics is also reaching 400 million metric tons in 2023. The lack of effective thermochemical processes for converting wet feedstocks and complex residues such as plastics is calling for hydrothermal gasification as an efficient approach to producing syngas. The demand for hydrogen production through greener approaches is also rising to compete with the commercial steam reforming of natural gas. Here, we review the conversion of biomass and plastics by hydrothermal gasification into hydrogen-rich syngas with a focus on the process parameters influencing the conversion of a variety of feedstock types. Parameters influencing hydrothermal gasification of biomass and plastics include temperature, pressure, reaction time, feedstock concentration, catalysts and reactor types. Several synergetic effects also influence product distribution during the co-processing of biomass and plastics during hydrothermal gasification. Processes that impact biomass conversion to syngas are hydrolysis, water–gas shift, methanation, hydrogenation, steam reforming and polymerization.

Improper disposal of organic waste leads to greenhouse gases, pollution, and health risks. Anaerobic digestion offers a sustainable solution by converting this waste into biogas and digestates, which contain valuable nutrients and stimulatory organic compounds that can be recycled to improve plant growth and support food production. Here we review the transformation of liquid and solid digestates into biostimulants by microalgal cultivation, vermicomposting, and insect-based bioconversion. These processes yield phytohormones, polysaccharides, betaines, humic substances, chitin, protein hydrolysates, and growth-promoting microbes, that enhance plant growth and resilience against environmental stresses. Due to the variability in digestate composition, we emphasize the need for optimized formulations, a deep understanding of synergistic interactions among bioactive compounds, and standardized extraction techniques to support broader applications.

Contamination of drinking water sources with recalcitrant organic pollutants is a major health issue requiring advanced oxidation processes for the degradation of such pollutants. Here we review the use of advanced oxidation processes-based treatment of water, wastewater, and sludge, with focus on singlet oxygen production, reactivity mechanisms, and applications. Processes for single-oxygen production include photochemical production, decomposition of hydrogen peroxide, ozonides, endoperoxides, and sulfate radical-based advanced oxidation. Singlet oxygen is one of the main non-radical reactive oxygen species that are generated during advanced oxidation processes. It is less reactive but highly selective toward electron-rich organic compounds, compared to hydroxyl and sulfate radicals. When generated in large quantities, singlet oxygen can be the dominant reactive oxygen species responsible for the degradation of targeted pollutants. Singlet oxygen is less affected by water matrix components including dissolved organic matter and scavenging by anions.

Solvent selection is essential for industrial and analytical extraction processes to ensure environmental safety and neutrality. Nevertheless, toxic and hazardous solvents are often used, due to their cost-effectiveness and ready availability. In green chemistry, alternative solvents such as supramolecular deep eutectic solvents are gaining attention due to their superior performance compared with traditional non-green solvents in certain applications. Here we review the use of supramolecular deep eutectic solvents as a green solvent for analytical and industrial liquid–liquid extraction processes, with focus on physicochemical properties, extraction conditions, the capacity factor, the enrichment factor, fuel desulfurization, extraction of biological active compounds, lignin valorization, and sample preparation.

Antibiotic contamination in wastewater is an urgent environmental and public health concern because conventional treatment methods are ineffective in completely removing these pollutants. Iron-modified biochar, synthesized from agricultural waste, is proposed as an efficient and sustainable media for removal of ciprofloxacin and amoxicillin from wastewater. Iron-modified biochar was synthesized using a simple pyrolysis process with corn and ferrous sulfate as feedstock. Adsorbents were characterized by fourier transform infrared spectroscopy, X-Ray diffraction, and scanning electron microscopy. Removal performance of antibiotics was evaluated under different conditions, including antibiotic dosage, concentration of hydrogen peroxide, pH, and amount of humic acid. The results demonstrated high removal efficiencies of 87% for ciprofloxacin and 83% for amoxicillin within 25 min. Mechanistic studies revealed the generation of hydroxyl radicals (^•OH) and singlet oxygen (¹O₂), and confirmed the activation of hydrogen peroxide in the system. These findings highlight the potential of iron-modified biochar as a sustainable and effective catalyst for antibiotic removal, offering a promising solution for reducing pharmaceutical contamination in wastewater.