Production of humic and fulvic acid analogs through the ultrasonication of low-rank lignite coals

Al-Akbari, Redhwan; Manasrah, Abdallah D.; Nassar, Nashaat N.

doi:10.1039/d3re00422h

Cited by 3 publications

(1 citation statement)

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“…Thus, in recent years, novel techniques that guarantee a higher yield of HS extraction from various raw materials have been tested. The application of hydrothermal extraction, as well as processes assisted by ultrasound or microwave, significantly improved the isolation efficiency, without a negative impact on the molecular structure of HSs. , In addition to such process modification, which leads to an increase in the amount of HSs obtained in relation to the mass of raw material used, the application of new types of extractants, including environmentally friendly agents, seems to be a challenge for the extraction technology of HSs. The solution in this regard may be the implementation of deep eutectic solvents (DESs), which are described in the literature as a green alternative to the traditional extractants used.…”

Section: Introductionmentioning

confidence: 99%

Application of Alkaline Deep Eutectic Solvents as a Green Alternative to the Traditional Extractants for the Isolation of Humic Substances

Nieweś,

Marecka,

Huculak-Mączka

2024

ACS Omega

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The presented study focused on the possibility of using alkaline deep eutectic solvents (ADESs) as green extractants for the isolation of humic substances (HSs) from peat and lignite in a process intensified by ultrasound. For this purpose, the extraction procedure was statistically described on the basis of the Box−Behnken design, and the carboxyl group content in the obtained products was optimized due to the ADES composition, ultrasound intensity, and extraction time. For optimal extraction conditions, the experimental carboxyl content in the isolated products was equal to 3.71 and 2.96 mmol g −1 for the HSs extracted from peat and lignite, respectively. These values were similar to the results for the reference samples, which were HSs extracted using 0.1 M NaOH, as well as humic acids and sodium humates purchased from Sigma-Aldrich. The qualitative assessment of the products obtained was based on spectroscopic methods, including FTIR, 1 H NMR, and UV−vis. The analyses carried out for the isolated samples revealed the characteristic structures of HSs, including components of aliphatic chains and aromatic core as well as carboxyl, ester, and amino groups. Simultaneously, the results of the spectral ratio of E 280 /E 472 showed the significant differences between the relative amount of lignin for the samples tested.

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Section: Introductionmentioning

confidence: 99%

Application of Alkaline Deep Eutectic Solvents as a Green Alternative to the Traditional Extractants for the Isolation of Humic Substances

Nieweś,

Marecka,

Huculak-Mączka

2024

ACS Omega

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Efficient extraction and formation mechanism of fulvic acid from lignite: Experimental and DFT studies

Li,

Ma,

Wang

et al. 2024

Journal of Environmental Management

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Humic Acids: Properties, Structure, and Application

Dauletbay,

Hanzheng,

Ongalbek

et al. 2024

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Humic substances (HSs) are a diverse class of natural compounds with no fixed chemical composition, formed from plant and microbial residues through the action of environmental factors and living organisms over many years. Despite extensive research spanning two centuries, the complex and variable nature of HSs' structure remains a subject of scientific inquiry. These substances, notably humic acids, fulvic acids, and humin, play crucial roles in ecological and environmental processes due to their abundant functional groups and resilience to biodegradation. This review explores the intricate structure and properties of HSs, their classification, and their occurrence in nature. It highlights the different models proposed to describe the structural fragments of humic acids, emphasizing their aromatic cores and diverse functional groups. The variability in the molecular weight distribution of HSs, attributed to their polydisperse nature, is also discussed, along with methods used for their determination, such as exclusion chromatography. Furthermore, the elemental and functional compositions of humic acids are examined, detailing their acid-base properties and capacity for heavy metal complexation. The synthesis of HSs from natural sources, such as soil, peat, coal, and artificial processes, is covered, showcasing methods like alkaline extraction and hydrothermal treatment. Recent advancements in artificial humification, including oxidative ammonolysis and Fenton reagent-based oxidation, are reviewed for their potential in producing environmentally friendly humic materials from lignin and waste biomass. The study concludes by underscoring the environmental significance and practical applications of HSs, particularly in agriculture, soil conditioning, and environmental remediation. The diverse properties and synthesis methods of HSs make them promising candidates for sustainable material production and environmental management. Humic acids are versatile compounds beneficial for human health due to their potent antioxidant properties, immune-modulating effects, and support for gastrointestinal health and detoxification. Structurally diverse, they feature groups like carboxyl, phenolic hydroxyl, quinones, ketonic carbonyls, amino, and sulfhydryl, contributing to their stability and amphiphilic nature. In pharmaceutical applications, they show promise for drug delivery, antioxidant therapies, wound healing, antimicrobial actions, and biofilm disruption, underlining their biocompatibility and safety. Key words:

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Production of humic and fulvic acid analogs through the ultrasonication of low-rank lignite coals

Abstract: We present a process utilizing an ultrasonic horn-type reactor for the conversion of lignite-coal into humic and fulvic acid analogs, achieving a 72% yield of humic acid analogs and 92% conversion.

Cited by 3 publications

References 93 publications

Application of Alkaline Deep Eutectic Solvents as a Green Alternative to the Traditional Extractants for the Isolation of Humic Substances

Application of Alkaline Deep Eutectic Solvents as a Green Alternative to the Traditional Extractants for the Isolation of Humic Substances

Efficient extraction and formation mechanism of fulvic acid from lignite: Experimental and DFT studies

Humic Acids: Properties, Structure, and Application

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