Environmental Chemistry Letters最新文献

Carbon neutral energies and fine chemicals are urgently needed in the context of the accelerating global warming and associated extreme weather events. Here we review the conversion of biomass into fuels and chemical compounds with focus on biomass properties, mechanisms of biomass thermal decomposition, bio-oil composition and generation, reactor types, pyrolytic classifications, pyrolysis of pure biomass components, and pyrolysis of wood. The main biomass components, namely cellulose, hemicellulose and lignin, are determined by the Van Soest protocol. Biomass decomposition can be explained by the one-step global mechanism, independent competitive or parallel reactions, the multi-component mechanism, the Broido-Shafizadeh scheme, the secondary tar cracking model and the Ranzi scheme. Pyrolysis can be classified into slow, intermediate, fast, and flash pyrolysis. Reactors comprise fixed bed-, fluidized bed- and multistage reactors.

Lithium is becoming a critical element for the economy due to the rising production of lithium-ion batteries, yet conventional extraction methods are slow, energy-intensive, and environmentally harmful. Recently, these issues have been solved partly by integrating advanced membranes in the extraction process. Here we review methods for lithium extraction with emphasis on conventional methods, membrane-based methods, multi-stage membrane-integrated systems, demonstration projects, techno-economical and life cycle assessment. Conventional methods include solar evaporation, precipitation, ion sieve adsorption, ion exchange, and electrochemical and solvent extraction. Membrane-based methods comprise reverse osmosis, nanofiltration, membrane distillation, membrane crystallization, forward osmosis and electrochemical membrane systems, ion-imprinted and ion sieve membranes, and liquid membranes. Liquid ores such as salt lakes and brines are a major source of lithium extraction and account for 2/3 of the global lithium production. Natural salt lakes and geothermal brines contain small lithium concentrations of 7.5–150 mg/L and high total dissolved solids, of 150–330 g/L. Nanofiltration allows about 85% lithium recovery with magnesium-to-lithium-ion selectivity of 0.4–0.75 and energy consumption of 35–48 kWh/kg. Electrodialysis reduces by 88% the magnesium-to-lithium ion ratio at a lower energy use of 10–38 kWh/kg of lithium. Supported liquid and ion-imprinted membranes are more energy-efficient, of 6–21 kWh/kg, but remain limited to laboratory-scale studies. We observed that the integration of membrane systems with conventional direct lithium extraction methods enhances the upstream lithium enrichment, followed by downstream recovery for more efficient overall lithium extraction.

There are about 10 million new cases of cognitive impairment diseases yearly, affecting 50 million people worldwide. Cognitive impairment is partly explained by pollutant exposure, with air pollution as one of the risk factor for dementia. Here we review the relationships between cognitive impairment and pollutant exposure, with focus on pollutant types, the entry of pollutants into the brain, symptoms and therapeutical drugs. Pollutants comprise solid and particulate compounds, organic and inorganic pollutants, bacteria, biotoxins and viruses. Symptoms include oxidative stress, neuroinflammation, aberrant cell death, and effects on the gut-brain axis. Cognitive impairment could be cured and prevented with antioxidants, anti-inflammatory compounds, inhibitors and activators, probiotics, and a healthy lifestyle. We present epidemiological evidence linking pollutants to cognitive impairment, and underlying neurotoxicity mechanisms. The olfactory mucosa and olfactory bulb pathway appears as the major route for pollutants entry into the brain parenchyma, which explains the strong epidemiological link between airborne pollutants and cognitive impairment. Oxidative stress and neuroinflammation trigger aberrant programmed cell death, including autophagy, apoptosis, and ferroptosis.

Per- and polyfluoroalkyl substances, known as ‘forever pollutants’ due to their very high stability in ecosystems, are industrial contaminants of emerging health concern commonly found in water. Remediation is particularly challenging because existing water and wastewater treatment plants are not designed to remove these pollutants. Here we review methods for the removal of per- and polyfluoroalkyl substances, with focus on the use of cyclodextrins, the cage molecules that can capture smaller substances. We present classical methods and adsorbents such as granular activated carbons, ion exchange resins, advanced oxidation processes, electrochemical degradation, metal–organic frameworks, and membrane filtration. Cyclodextrin-based materials include cross-linked compounds, molecularly imprinted polymers, covalent organic frameworks, and silica hybrids. We describe the complex formed by inclusion of a per- and polyfluoroalkyl substance into a cyclodextrin. We compare the use of cyclodextrins with other removal methods. Cyclodextrins are cyclic oligosaccharides used to prepare polyfunctional materials by cross-linking, immobilization, coating, or self-assembly. Cyclodextrins-based materials are much more efficient for the remediation of per- and polyfluoroalkyl substances, because these cage molecules can be designed to recognize specifically pollutants. As a consequence, cyclodextrins-based materials display much higher adsorption coefficients, in the range of 10⁴—10⁶ L per Kg, compared to less than 10⁴ L per Kg for activated carbon.

Polycyclic aromatic hydrocarbons are well-known pollutants, yet some apects of their osteotoxicity and neurotoxicity have not been reviewed. Here we review benzo[a]pyrene-induced osteotoxicity and neurotoxicity in fish and mammals, with focus on phenotypic changes, cell development, molecular signaling pathways, key gene expression, and epigenetic modifications. Benzo[a]pyrene impairs bone health by suppressing osteoblast formation, promoting bone resorption, and disrupting remodeling, primarily through dysregulation of key transcription factors and signaling pathways. In neural tissues, metabolically-activated benzo[a]pyrene generates reactive oxygen species, triggering oxidative stress, dysregulation of gene expression, mitochondrial dysfunction, altered neurotransmitter levels, and neuronal apoptosis. Benzo[a]pyrene induced multigenerational osteotoxicity in 42% of fish studies, but 0% in rodent studies. It induced multigenerational neurotoxicity in 25% of fish studies and 15% in rodent studies. Epigenetic modifications are a critical mechanism linking benzo[a]pyrene exposure to these multigenerational and transgenerational toxicity in bone and neural systems of both fish and rodents.

The accelerating climate change requires rapid techniques to both sequester carbon dioxide and recycle solid waste. Here we review the accelerated carbonation of fly ash from municipal solid waste with emphasis on carbonation methods, carbon dioxide sequestration capability, influence of carbonation on fly ash properties, fly ash as a cementitious material, non-conventional uses of fly ash, environmental and economic benefits, mixing with other waste materials, pilot and industrial applications, and limitations. We observe that the accelerated carbonation of fly ash allows for carbon dioxide capture of up to 0.24 g CO₂ per gram of ash, reduces heavy metal leaching, facilitates the reuse of stabilized ashes, and generates materials suitable for a wide range of uses. Limitations include possible pH-induced remobilization of toxic metals such as cadmium, chromium, and antimony.

Bioaerosols represent a major health issue because they contain viruses, bacteria, biological fragments or residues and fungal spores. Humans are exposed to nearly 10⁴ viable bacteria and 10⁴ viable fungi per cubic metre of indoor air. Here, we review bioaerosols with emphasis on their sources, behaviour, detection methods, mitigation, transmission, and photocatalytic disinfection. Disinfection methods include fibrous photocatalytic membranes with interception efficiency comparable to commercial masks and high bactericidal efficiency, Z-scheme and S-scheme heterojunctions-based materials, biofilms loaded with composite catalysts, and photocatalytic filters coupled with air ionizers. Bioaerosols inactivation reaches 99.99% in 4 h under ultraviolet light, and 99.3% in 14.1 s under visible light using advanced heterojunction photocatalysts.