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25 pages, 1051 KiB

Open AccessArticle

Microplastic-Mediated Heavy Metal Uptake in Lettuce (Lactuca sativa L.): Implications for Food Safety and Agricultural Sustainability

by Bhakti Jadhav and Agnieszka Medyńska-Juraszek

Molecules 2025, 30(11), 2370; https://doi.org/10.3390/molecules30112370 - 29 May 2025

Abstract

This study investigates how different types of microplastics (MPs)—fibers, glitter, plastic bags, and plastic bottles—influence heavy metal uptake in lettuce (Lactuca sativa L.), a commonly consumed leafy vegetable. A controlled eight-week pot experiment was conducted in a greenhouse using contaminated loamy sand [...] Read more.

This study investigates how different types of microplastics (MPs)—fibers, glitter, plastic bags, and plastic bottles—influence heavy metal uptake in lettuce (Lactuca sativa L.), a commonly consumed leafy vegetable. A controlled eight-week pot experiment was conducted in a greenhouse using contaminated loamy sand soil (polluted with Cd, Pb, Cu, and other metals) collected from a smelter-impacted area. Microplastics were added at a concentration of 70–80 mg/kg, and lettuce seedlings were grown under phytotron conditions (22 ± 2 °C, 60 ± 5% RH, 16 h light/8 h dark) without fertilizers or external contaminants. Plant roots and shoots were harvested, and heavy metals were analyzed via MP-AES and ICP-MS. The results showed that MPs altered heavy metal mobility, bioavailability, and plant uptake. Copper accumulation in leaves decreased substantially across MP treatments, from 80.84 mg/kg in the control to 26.35 mg/kg (glitter), whereas lead and cadmium concentrations increased significantly in roots under fiber and glitter exposure (Pb increased from 12.13 mg/kg to 33.57 mg/kg and Cd from 1.70 mg/kg to 2.05 mg/kg in fiber treatment). Cobalt accumulation in leaves increased under the plastic bag treatment, indicating MP-specific metal interactions. Root growth was also affected, with fibers promoting elongation and plastic bottles restricting it. Sequential extraction revealed that MPs modified metal partitioning in soil, with Pb and Ni more strongly retained in stable fractions under some treatments. Observed trends in soil pH and organic matter content were associated with changes in metal mobility, highlighting the potential role of soil properties in mediating microplastic–metal interactions. These findings highlight the role of MPs as mediators of heavy metal transport in crops and underscore the need for clear regulatory guidelines that limit microplastic contamination in agricultural soils and promote routine monitoring to safeguard food safety and crop health. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

25 pages, 2282 KiB

Open AccessArticle

Production of Green Diesel via the Ni/Al Mo Hydrotalcite Catalyzed Deoxygenation of Rapeseed Oil

by Giuseppe Di Vito Nolfi, Katia Gallucci, Vittoria Mucciante and Leucio Rossi

Molecules 2025, 30(8), 1699; https://doi.org/10.3390/molecules30081699 - 10 Apr 2025

Viewed by 260

Abstract

Growing concern about anthropogenic climate change and the continuous increase in the energy demand have driven the need to explore new energy sources, particularly in the transportation sector. Biodiesel is one of the most widely used biofuels, but its disadvantages restrict its use [...] Read more.

Growing concern about anthropogenic climate change and the continuous increase in the energy demand have driven the need to explore new energy sources, particularly in the transportation sector. Biodiesel is one of the most widely used biofuels, but its disadvantages restrict its use in blends with conventional diesel. A better alternative is green diesel, a hydrocarbon biofuel that can be used in its pure form and is produced through the catalytic deoxygenation of vegetable oils. In this study, a NiMoAl catalyst derived from layered double hydroxides (LDHs) was synthesized and used for the catalytic deoxygenation of rapeseed oil to produce green diesel. The catalyst was characterized using IR, XRD, and BET analysis. The reactions were carried out in a batch reactor, and parameters such as the temperature, pressure, catalyst loading, and reaction time were examined. The results demonstrated that the complete conversion of rapeseed oil was achieved under optimal conditions (320 °C, 40 bar H₂, 4 wt% catalyst), with a diesel-range hydrocarbon content of over 90%. The recyclability of the catalyst was also evaluated, showing sustained activity over multiple reaction cycles while maintaining high conversion and selectivity toward hydrocarbons in the diesel range. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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16 pages, 4212 KiB

Open AccessArticle

Enhancing Photostability of Prochloraz via Designing Natural Acid-Derived Prochloraz-Based Ionic Liquids

by Zhiqiang Gao, Fengmao Liu, Qingrong Peng and Wenzhuo Wang

Molecules 2025, 30(7), 1641; https://doi.org/10.3390/molecules30071641 - 7 Apr 2025

Viewed by 308

Abstract

Converting pesticides into ionic liquids by designing counterions can modulate their physicochemical properties, thus improving their efficacy and environmental safety. In this study, eight prochloraz-based ionic liquids (PILs) were synthesized using natural organic acids, and their physicochemical properties, toxicity, antifungal activity, and efficacy [...] Read more.

Converting pesticides into ionic liquids by designing counterions can modulate their physicochemical properties, thus improving their efficacy and environmental safety. In this study, eight prochloraz-based ionic liquids (PILs) were synthesized using natural organic acids, and their physicochemical properties, toxicity, antifungal activity, and efficacy in postharvest mango preservation were evaluated. The results showed that the physicochemical properties of propiconazole, including water solubility, logK_ow, surface activity, and light stability, could be adjusted by selecting counterions with varying structures. These properties were correlated with toxicity to zebrafish embryos and antifungal activity against Colletotrichum gloeosporioides. Notably, except for the benzoate PIL, the photostability of the other seven PILs was enhanced under UV irradiation, with the cinnamate PIL exhibiting a half-life 2.28 times longer than prochloraz. Spectral analysis indicated that the anions influenced photostability by shielding or interacting with the cations. Furthermore, the three selected PILs improved pesticide deposition on the mango surface during preservation, and the salicylate PIL enhanced pesticide penetration into the fruit, potentially contributing to its therapeutic activity. In conclusion, the ionic liquid strategy offers an effective method to modify pesticide properties, improve photostability, reduce losses, and optimize pesticide formulation. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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31 pages, 3830 KiB

Open AccessArticle

Oxidation of α-Pinene on the Ti-SBA-15 Catalyst Obtained Using Orange Peel Waste as Components of the Synthesis Gel

by Jadwiga Grzeszczak, Agnieszka Wróblewska, Beata Michalkiewicz, Małgorzata Dzięcioł and Katarzyna Janda-Milczarek

Molecules 2025, 30(7), 1627; https://doi.org/10.3390/molecules30071627 - 5 Apr 2025

Cited by 1 | Viewed by 324

Abstract

α-Pinene is a very valuable natural raw material for organic syntheses, which is of increasing interest to scientists due to its renewability and relatively low price. This work presents the studies on the oxidation of α-pinene in the presence of two mesoporous titanium-silicate [...] Read more.

α-Pinene is a very valuable natural raw material for organic syntheses, which is of increasing interest to scientists due to its renewability and relatively low price. This work presents the studies on the oxidation of α-pinene in the presence of two mesoporous titanium-silicate catalysts: standard Ti-SBA-15 and Ti-SBA-15 material, which was obtained by a new and green way using orange peel waste as bio-templates (Ti-SBA-15_orange peels). For the synthesis of the Ti-SBA-15 catalysts, the following raw materials were used: Pluronic P123 as the template (template usually used in the synthesis of SBA-15 materials), tetraethyl orthosilicate as the silicon source, hydrochloric acid, deionized water, and tetraisopropyl orthotitanate as the titanium source. For the synthesis of Ti-SBA-15_orange peels, a catalyst was also properly prepared, and orange peel waste as the co-templates (renewable templates) were used. The two obtained Ti-SBA-15 materials were characterized by the following instrumental methods: XRD, SEM, EDX, UV-Vis, and FTIR. Moreover, the specific surface area and pore size distribution were investigated for these catalysts with help from the nitrogen adsorption–desorption method. Catalytic tests of the obtained catalysts were performed in the oxidation of α-pinene with oxygen and by the method which did not use any solvent (α-pinene was simultaneously the raw material and solvent in this process). During the catalytic tests, the effect of temperature, catalyst content, and reaction time on the selectivities of the appropriate products and the conversion of α-pinene were studied. Depending on the conditions of the oxidation process, the catalyst obtained with the use of orange peels as co-templates showed similar or even higher activity than the standard Ti-SBA-15 catalyst. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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10 pages, 836 KiB

Open AccessArticle

A Facile, Sustainable One-Pot Synthesis of the Spiro-Dimers of α-Tocopheramine and Its N-Methyl Derivative

by Anjan Patel and Thomas Rosenau

Molecules 2025, 30(6), 1269; https://doi.org/10.3390/molecules30061269 - 12 Mar 2025

Viewed by 461

Abstract

α-Tocopheramine and N-methyl-α-tocopheramine are used as stabilizers in the spinning of cellulosic fibers from solutions in 1,3-dialkylimidazolium ionic liquids. Upon aging, they form chromophoric degradation products, among which the spiro-dimers are major components. These compounds have proved to be otherwise inaccessible so [...] Read more.

α-Tocopheramine and N-methyl-α-tocopheramine are used as stabilizers in the spinning of cellulosic fibers from solutions in 1,3-dialkylimidazolium ionic liquids. Upon aging, they form chromophoric degradation products, among which the spiro-dimers are major components. These compounds have proved to be otherwise inaccessible so far, although they are urgently needed as chromatographic standards in spinning baths and fiber analysis. In this work, the spiro-dimers of α-tocopheramine and N-methyl-α-tocopheramine have been synthesized. Extensive optimization of reaction conditions, solvents and oxidants resulted in a sustainable one-pot protocol that provided quantitative yields without the need for product purification and with the easy recycling of the solvent. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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25 pages, 6133 KiB

Open AccessArticle

Chemical Looping CH₄ Reforming Through Isothermal Two-Step Redox Cycling of SrFeO₃ Oxygen Carrier in a Tubular Solar Reactor

by Stéphane Abanades, Xinhe Wang and Srirat Chuayboon

Molecules 2025, 30(5), 1076; https://doi.org/10.3390/molecules30051076 - 26 Feb 2025

Viewed by 481

Abstract

The chemical looping reforming of methane using an SrFeO₃ oxygen carrier to produce synthesis gas from solar energy was experimentally investigated and validated. High-temperature solar heat was used to provide the reaction enthalpy, and therefore the methane feedstock was entirely dedicated to [...] Read more.

The chemical looping reforming of methane using an SrFeO₃ oxygen carrier to produce synthesis gas from solar energy was experimentally investigated and validated. High-temperature solar heat was used to provide the reaction enthalpy, and therefore the methane feedstock was entirely dedicated to producing syngas. The two-step isothermal process encompassed partial perovskite reduction with methane (partial oxidation of CH₄) and exothermic oxidation of SrFeO_3-δ with CO₂ or H₂O splitting under the same operating temperature. The oxygen carrier material was shaped in the form of a reticulated porous foam structure for enhancing heat and mass transfer, and it was cycled in a solar-heated tubular reactor under different operating parameters (temperature: 950–1050 °C, methane mole fraction: 5–30%, and type of oxidant gas: H₂O vs. CO₂). This study aimed to assess the fuel production capacity of the two-step process and to demonstrate the potential of using strontium ferrite perovskite during solar cycling for the first time. The maximum H₂ and CO production rates during CH₄-induced reduction were 70 and 25 mL/min at 1000 °C and 15% CH₄ mole fraction. The increase in both the cycle temperature and the methane mole fraction promoted the reduction step, thereby enhancing syngas yields up to 569 mL/g during reduction at 1000 °C under 30% CH₄ (778 mL/g including both cycle steps), and thus outperforming the performance of the benchmark ceria material. In contrast, the oxidation step was not significantly affected by the experimental conditions and the material’s redox performance was weakly dependent on the nature of the oxidizing gas. The syngas yield remained above 200 mL/g during the oxidation step either with H₂O or CO₂. Twelve successive redox cycles with stable patterns in the syngas production yields validated material stability. Combining concentrated solar energy and chemical looping reforming was shown to be a promising and sustainable pathway toward carbon-neutral solar fuels. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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12 pages, 2700 KiB

Open AccessArticle

Synthesis of Thiazolo[5,4-d]thiazoles in an Eco-Friendly L-Proline–Ethylene Glycol Mixture

by Thiên Thuý Trang Nguyễn, Jean-François Longevial and Stéphanie Hesse

Molecules 2025, 30(4), 938; https://doi.org/10.3390/molecules30040938 - 18 Feb 2025

Viewed by 592

Abstract

The hazardousness of solvents used in synthetic organic chemistry is well established. In this context, it is relevant to search for safer and greener alternatives. Within the last decades, deep eutectic solvents have been considered as possible and promising alternatives. Consequently, this study [...] Read more.

The hazardousness of solvents used in synthetic organic chemistry is well established. In this context, it is relevant to search for safer and greener alternatives. Within the last decades, deep eutectic solvents have been considered as possible and promising alternatives. Consequently, this study aims at using deep eutectic solvents to synthesize an emerging class of heteroaromatic compounds named thiazolo[5,4-d]thiazoles, for which interest is growing in the field of organics, electronics, and biology. To address this challenge, we developed a straightforward synthetic protocol consisting of condensing dithiooxamide and aromatic aldehyde in deep eutectic solvents to yield the desired thiazolo[5,4-d]thiazole without further purification. The first hit was obtained with the well-known L-proline:glycerol (1:2) mixture at 130 °C. However, dithiooxamide is degraded under these conditions, leading to the formation of impurities that may arise from the consequent amount of reactive L-proline. Reaction conditions were optimized by modifying the deep eutectic solvent nature and proportions, applying various temperatures, changing the activation and heating source, or adding auxiliary oxidants. As a consequence, eight thiazolo[5,4-d]thiazoles were synthesized in equal or better yields (20 to 75%) than the reported procedure under safe and eco-friendly conditions in a mixture of L-proline and ethylene glycol (1:50) with sodium metabisulfite at 130 °C for one hour. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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12 pages, 1733 KiB

Open AccessArticle

Thermal Characterization and Heat Capacities of Seven Polyphenols

by Iván Montenegro, Carmen Pérez, Begoña González, Ángeles Domínguez and Elena Gómez

Molecules 2025, 30(1), 199; https://doi.org/10.3390/molecules30010199 - 6 Jan 2025

Viewed by 969

Abstract

Polyphenolic compounds are key elements in sectors such as pharmaceutics, cosmetics and food; thus, their physicochemical characterization is a vital task. In this work, the thermal behavior of seven polyphenols (trans-resveratrol, trans-polydatin, kaempferol, quercetin, myricetin, hesperidin, and (−)-epicatechin) was investigated [...] Read more.

Polyphenolic compounds are key elements in sectors such as pharmaceutics, cosmetics and food; thus, their physicochemical characterization is a vital task. In this work, the thermal behavior of seven polyphenols (trans-resveratrol, trans-polydatin, kaempferol, quercetin, myricetin, hesperidin, and (−)-epicatechin) was investigated with DSC (differential scanning calorimetry) and TGA (thermogravimetric analysis). Melting temperatures, enthalpies of fusion and decomposition temperatures were determined, and heat capacities were measured in the temperature range from 283.15 K to 363.15 K. Results were compared to the scarce experimental data available in the literature, showing a satisfactory agreement. All compounds were found to be thermally stable until melting, upon which they rapidly decomposed. Myricetin was the only polyphenol that presented polymorphic behavior, exhibiting two phase transitions prior to melting. Heat capacities increased minimally with temperature in the studied range. In addition, the group contribution method developed by Marrero and Gani was used to estimate the thermal properties of the polyphenols, achieving high accuracy for melting temperatures. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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15 pages, 4162 KiB

Open AccessArticle

Understanding the Enzymatic Synthesis of a New Biolubricant: Decane-1,10-diyl bis(2-methylpentanoate)

by Salvadora Ortega-Requena, Fuensanta Máximo, María Claudia Montiel, María Gómez, María Dolores Murcia and Josefa Bastida

Molecules 2025, 30(1), 52; https://doi.org/10.3390/molecules30010052 - 26 Dec 2024

Viewed by 820

Abstract

The value of branched esters comes from the special properties they have in cold environments, which allow them to remain liquid over a wide range of temperatures. These properties make them useful for application in the cosmetic industry or as lubricant additives. This [...] Read more.

The value of branched esters comes from the special properties they have in cold environments, which allow them to remain liquid over a wide range of temperatures. These properties make them useful for application in the cosmetic industry or as lubricant additives. This paper presents the studies carried out to ascertain the operational feasibility of the enzymatic esterification of 2-methylpentanoic acid (MPA) with 1,10-decanediol (DD), with the objective of obtaining a novel molecule: decane-1,10-diyl bis(2-methylpentanoate) (DDBMP). The enzymatic reaction is conducted in a thermostated batch reactor, utilizing the commercially available immobilized lipase Lipozyme^® 435 in a solvent-free medium. The reaction conversion is determined by an acid number determination and a gas chromatographic analysis. The most optimal result is achieved at a temperature of 80 °C, a biocatalyst concentration of 2.5% (w/w), and a non-stoichiometric substrate relation. A preliminary economic study and the calculation of Green Metrics has established that the operation with a 30% molar excess of acid is the best option to obtain a product with 92.6% purity at a lower cost than the other options and in accordance with the 12 Principles of Green Chemistry. The synthetized diester has a viscosity index of 210, indicating that this new molecule can be used as a biolubricant at extreme temperatures. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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22 pages, 7696 KiB

Open AccessArticle

Hollow Biomass Adsorbent Derived from Platanus Officinalis Grafted with Polydopamine-Mediated Polyethyleneimine for the Removal of Eriochrome Black T from Water

by Zefeng Jiang, Tongyang Song, Bowen Huang, Chengqiang Qi, Zifu Peng, Tong Wang, Yuliang Li and Linjing Ye

Molecules 2024, 29(23), 5730; https://doi.org/10.3390/molecules29235730 - 4 Dec 2024

Cited by 1 | Viewed by 785

Abstract

Platanus officinalis fibers (PFs) taking advantage of high-availability, eco-friendly and low-cost characteristics have attracted significant focus in the field of biomaterial application. Polyethyleneimine grafted with polydopamine on magnetic Platanus officinalis fibers (PEI-PDA@M-PFs) were prepared through a two-step process of mussel inspiration and the [...] Read more.

Platanus officinalis fibers (PFs) taking advantage of high-availability, eco-friendly and low-cost characteristics have attracted significant focus in the field of biomaterial application. Polyethyleneimine grafted with polydopamine on magnetic Platanus officinalis fibers (PEI-PDA@M-PFs) were prepared through a two-step process of mussel inspiration and the Michael addition reaction, which can work as an effective multifunctional biomass adsorbent for anionic dye with outstanding separation capacity and efficiency. The as-prepared PEI-PDA@M-PFs possess desirable hydrophilicity, magnetism and positive charge, along with abundant amino functional groups on the surface, facilitating efficient adsorption and the removal of Eriochrome Black T (EBT) dyes from water. In addition to the formation mechanism, the adsorption properties, including adsorption isotherms, kinetics, and the reusability of the absorbent, were studied intensively. The as-prepared PEI-PDA@M-PFs achieved a theoretical maximum adsorption capacity of 166.11 mg/g under optimal conditions (pH 7.0), with 10 mg of the adsorbent introduced into the EBT solution. The pseudo-second-order kinetic and Langmuir models were well matched with experimental data. Moreover, thermodynamic data ΔH > 0 revealed homogeneous chemical adsorption with a heat-absorption reaction. The adsorbent remained at high stability and recyclability even after five cycles of EBT adsorption processes. These above findings provide new insights into the adsorption processes and the development of biologic material for sustainable applications. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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Review

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25 pages, 4473 KiB

Open AccessReview

Emerging Biochemical Conversion for Plastic Waste Management: A Review

by Zhongchuang Liu, Siu Hua Chang and Gilles Mailhot

Molecules 2025, 30(6), 1255; https://doi.org/10.3390/molecules30061255 - 11 Mar 2025

Viewed by 948

Abstract

In recent years, vast amounts of plastic waste have been released into the environment worldwide, posing a severe threat to human health and ecosystems. Despite the partial success of traditional plastic waste management technologies, their limitations underscore the need for innovative approaches. This [...] Read more.

In recent years, vast amounts of plastic waste have been released into the environment worldwide, posing a severe threat to human health and ecosystems. Despite the partial success of traditional plastic waste management technologies, their limitations underscore the need for innovative approaches. This review provides a comprehensive overview of recent advancements in chemical and biological technologies for converting and utilizing plastic waste. Key topics include the technical parameters, characteristics, processes, and reaction mechanisms underlying these emerging technologies. Additionally, the review highlights the importance of conducting economic analyses and life cycle assessments of these emerging technologies, offering valuable insights and establishing a robust foundation for future research. By leveraging the literature from the last five years, this review explores innovative chemical approaches, such as hydrolysis, hydrogenolysis, alcoholysis, ammonolysis, pyrolysis, and photolysis, which break down high-molecular-weight macromolecules into oligomers or small molecules by cracking or depolymerizing specific chemical groups within plastic molecules. It also examines innovative biological methods, including microbial enzymatic degradation, which employs microorganisms or enzymes to convert high-molecular-weight macromolecules into oligomers or small molecules through degradation and assimilation mechanisms. The review concludes by discussing future research directions focused on addressing the technological, economic, and scalability challenges of emerging plastic waste management technologies, with a strong commitment to promoting sustainable solutions and achieving lasting environmental impact. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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40 pages, 4378 KiB

Open AccessReview

Review on Gallium in Coal and Coal Waste Materials: Exploring Strategies for Hydrometallurgical Metal Recovery

by Ewa Rudnik

Molecules 2024, 29(24), 5919; https://doi.org/10.3390/molecules29245919 - 15 Dec 2024

Cited by 2 | Viewed by 1999

Abstract

Gallium, a critical and strategic material for advanced technologies, is anomalously enriched in certain coal deposits and coal by-products. Recovering gallium from solid residues generated during coal production and utilization can yield economic benefits and positive environmental gains through more efficient waste processing. [...] Read more.

Gallium, a critical and strategic material for advanced technologies, is anomalously enriched in certain coal deposits and coal by-products. Recovering gallium from solid residues generated during coal production and utilization can yield economic benefits and positive environmental gains through more efficient waste processing. This systematic literature review focuses on gallium concentrations in coal and its combustion or gasification by-products, modes of occurrence, gallium-hosting phases, and hydrometallurgical recovery methods, including pretreatment procedures that facilitate metal release from inert aluminosilicate minerals. Coal gangue, and especially fly ashes from coal combustion and gasification, are particularly promising due to their higher gallium content and recovery rates, which can exceed 90% under optimal conditions. However, the low concentrations of gallium and the high levels of impurities in the leachates require innovative and selective separation techniques, primarily involving ion exchange and adsorption. The scientific literature review revealed that coal, bottom ash, and coarse slag have not yet been evaluated for gallium recovery, even though the wastes can contain higher gallium levels than the original material. Full article

(This article belongs to the Special Issue 10th Anniversary of Green Chemistry Section)

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