Environmental Chemistry Letters最新文献

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.

Biomass offers a promising alternative for producing biofuels and chemicals through hydrothermal liquefaction, a process known for its ability to convert complex organic materials into valuable liquid products. Optimizing hydrothermal liquefaction for large-scale application involves understanding the underlying mechanisms and addressing key scientific and technical issues. We review hydrothermal liquefaction of biomass-derived chemicals, focusing on the breakdown and depolymerization of cellulose, hemicellulose, lignin, lipids, and proteins under hydrothermal conditions. We examine critical parameters such as reaction temperature, pressure, solvent selection, and catalyst choice, and their impact on product yield and quality. Catalytic routes transform key intermediates, such as 5-hydroxymethylfurfural and levulinic acid, into high-value liquid fuels and chemicals, offering significant potential for sustainable fuel production. Recent advances in process optimization are discussed.

The textile, printing and dyeing industries are producing wastewater containing hazardous dye contaminants, which require advanced remediation methods to avoid environmental pollution. Here we review graphene oxide-based materials for the removal of dye contaminants in waters and wastewater, with focus on the properties of graphene oxide, adsorption mechanisms, factors controlling the adsorption, and applications. Dye adsorption is controlled by temperature, adsorbent and dye concentrations, and adsorption time. Graphene oxide composites include membranes and aerogels. Graphene oxide displays suitable hydrophilicity, acid‐alkali resistance, and strong adsorption capabilities. Increasing the surface activity and specific surface area of graphene oxide promotes the adsorption of graphene oxide on textile wastewater and dyeing wastewater.

Photodegradation in sunlit waters is a major process of contaminant abatement, yet underlying chemical processes in the presence of dissolved organic matter are poorly known. Long-lived photo-oxidants are reactive species formed when the chromophoric dissolved organic matter absorbs sunlight, and they are involved in the degradation of contaminants. Previous works identified long-lived photo-oxidants with phenoxy radicals, which could be formed upon oxidation of natural phenols by the excited triplet states of chromophoric dissolved organic matter. Here, we generated reactive phenoxy radicals by direct ultraviolet-A photolysis of 2-nitrophenol and 4-nitrophenol. We measured the second-order rate constants for reaction of these phenoxy radicals with 2,4,6-trimethylphenol, a model electron-rich phenol. Results show rate constants of 9.39 × 10⁸(M⁻¹s⁻¹) for the 2-nitrophenoxyl radical, and 1.56 × 10⁸(M⁻¹s⁻¹) for the 4-nitrophenoxyl radical. These values are slightly lower than the typical rate constant of the reaction between 2,4,6-trimethylphenol and the excited triplet states of chromophoric dissolved organic matter, of 3 × 10⁹(M⁻¹s⁻¹). This means that 2,4,6-trimethylphenol would not be degraded to comparable extents by the excited triplet states of chromophoric dissolved organic matter and by long-lived photo-oxidants, if long-lived photo-oxidants were generated solely by the triplet states of chromophoric dissolved organic matter. Overall, findings suggest the occurrence of new pathway involving the direct photolysis of organic matter phenols that generates long-lived photo-oxidants.

Microplastics have emerged as a global environmental issue, inducing harmful effects on marine ecosystems and biodiversity. Their small size allows them to easily disperse across different ecosystems and enter the marine food chain, increasingly threatening coral ecosystems. This study hypothesizes that exposure to polyethylene microplastics alters the structure of coral skeletons. To test this, Briareum violacea corals were cultured under controlled conditions and exposed to polyethylene microplastics at concentrations of 0, 5, 10, 50, 100, and 300 mg/L for seven days. Skeletal structures were analyzed using X-ray diffraction, while inductively coupled plasma mass spectrometry was employed to assess changes in skeletal solubility and measure total calcium ion concentrations in seawater. The results revealed a transformation of coral skeletons from aragonite calcium carbonate crystals to amorphous calcium carbonate, as observed through X-ray diffraction analysis, with polyethylene microplastics causing this transformation to begin at a concentration of 10 mg/L. Additionally, skeletal solubility increased by 7.4-fold, as inferred from calcium ion concentrations measured by inductively coupled plasma mass spectrometry. Here we demonstrate that polyethylene microplastic exposure directly drives the degradation of coral skeletons, emphasizing the urgency of mitigating plastic pollution to safeguard coral ecosystems.

Anaerobic digestion constitutes a sustainable method for waste management and renewable energy generation, addressing significant environmental and societal challenges. The growing global waste crisis and the increasing momentum toward sustainable energy solutions emphasize the critical need to enhance anaerobic digestion technology for improved efficiency and environmental advantages. This process mitigates waste accumulation, enhances energy security, and reduces greenhouse gas emissions, providing a feasible solution within the framework of a circular bioeconomy. Here, we review the principles of anaerobic digestion and biogas production, focusing on agricultural waste and the utilization of biogas for energy within a sustainable framework. We specifically explore biogas applications in rural and industrial settings, assess the environmental impacts, and discuss the regulatory landscape with insights from China and Europe. This study reveals that the strategic implementation of anaerobic digestion can markedly improve energy yield and sustainability, demonstrating how focused policies and advanced technological practices can optimize biogas utilization. The review enhances comprehension of environmental impacts, emphasizing insights from China and Europe as key examples.

Endocrine-disrupting compounds such as 4-nonylphenol pose significant societal and environmental challenges due to their toxicity and estrogenic properties, adversely impacting human health, wildlife, and aquatic ecosystems. The complexity of 4-nonylphenol environmental behavior, its transport mechanisms, and the challenges in mitigating its impact through adsorption processes are critical. Here we review 4-nonylphenol contamination with focus on remediation by adsorption. We found that biofilms can accumulate 4-nonylphenol in aquatic environments; adsorption equilibrium in soils is influenced by temperature; and microplastics facilitate the transport of 4-nonylphenol through ecosystems. We present effective materials for 4-nonylphenol removal, including graphene oxides, silica, zeolites, and activated carbons. We analyze key variables influencing adsorption efficiency, offering a comprehensive database and insights into optimal removal strategies.

Silver chloride nanoparticles and microplastics are polluting in surface waters, yet their interactions, associated toxicity and environmental risks are poorly known. Here we hypothesized that polystyrene microplastics could enhance the phototransformation of silver chloride nanoparticles and modify their toxicity. We conducted phototransformation of silver chloride nanoparticles with polystyrene microplastics under light irradiation. The photo-dissolution of silver chloride nanoparticles and photo-reduction of silver ions were determined in both double-distilled-water and environmental waters. We found that polystyrene microplastics highly enhanced the phototransformation of silver chloride nanoparticles by hydroxyl radicals, singlet oxygen, and triplet state microplastics, leading to the release of silver ions and chloride ions. Subsequently, the silver ions were reduced to silver nanoparticles by superoxide radicals. Consequently, the silver species transformation increased the toxicity of silver chloride nanoparticles even at environmental concentration, as evidenced by survival rate of zebrafish larvae reduced from 100% to 23.3%. This is the first study to show that polystyrene microplastics can enhance the phototransformation of silver chloride nanoparticles to silver nanoparticles, thereby increasing the environmental risks of silver chloride nanoparticles in environmental waters.

Tetracyclines are broad-spectrum antibiotics used as human and veterinary ailments, anticancer and antiviral agents, and for treating inflammations including arthritis and the Huntington’s disease. However, their inappropriate usage and disposal induce environmental pollution due to their persistency, hydrophilicity and limited volatility, requiring advanced remediation methods. Here, we review techniques for tetracycline removal, including adsorption, advanced oxidation and filtration. Materials to treat tetracycline pollution include aged microplastics, green materials, chemical compounds, sonocatalysts and membranes. Complete tetracycline removal is achieved by using membranes, sonocatalysis and composites. Green composites appear eco-friendly for wastewater treatment. Chemically-synthesized composites are mainly used in photocatalysis, oxidative and enzymatic degradation.