Advances in fulvic acid extraction from lignite: techniques, challenges, and applications.

Fulvic acid (FA) is the main active component of humic substances (HS) due to its molecular properties, solubility, reactivity, and essential role in enhancing soil health and supporting plant growth. It forms through the breakdown of organic matter and can be sourced from various natural origins, including low-rank coal, peat, and soil. The extraction of FA from low-rank coal has attracted scientific interest because of its low cost and broad applications in agriculture, environmental cleanup, and medicine. However, extracting FA from natural sources is challenging because yields and quantities are often limited. Moreover, the quality of extracted FA depends on the extraction method, with different techniques offering varying efficiencies, requiring a detailed understanding of the process. This review explores FA's diverse properties and extraction methods, emphasizing its potential as a sustainable agent for environmental remediation and as a nutraceutical. FA possesses promising capabilities to influence the geochemical behavior of metals through adsorption, complexation, and redox reactions, helping to reduce toxicity and remove contaminants such as lead (Pb), chromium (Cr), and mercury (Hg). Its amphiphilic nature also enhances its effectiveness in agriculture by supporting crop development and soil vitality, while exerting immunomodulatory effects on human health. Various chemical and biological extraction methods for FA are thoroughly reviewed, highlighting challenges in achieving efficient industrial-scale production. Despite its potential, variability in quality due to differences in raw materials and extraction techniques necessitates further research to fully realize FA's capabilities for environmental cleanup, sustainable agriculture, and health benefits. This review offers an overview of the current state of FA research and its potential in technological development.

© 2026. The Author(s), under exclusive licence to Springer Nature Switzerland AG.