The broad application and mechanism of humic acids for treating environmental pollutants: Insights from bibliometric analysis

Abstract

Humic acids (HAs) are macromolecular substances that play important roles in different areas of soil, atmosphere, water, and ecological environment restoration. Here, we applied bibliometric analysis to systematically evaluate HAs applications in the environmental field. In-depth analysis of the publication characteristics of 9145 articles published from 1980 to 2020 revealed that the number of articles published on HAs increased rapidly, with China having the largest number of publications (3109), followed by the United States (1949) and Germany (679). Specifically, the Chinese Academy of Sciences had the largest number of publications (647) and was the center of the most productive institutional cooperation network. HAs applications and mechanisms for treating organic pollutants and heavy metals are important research topics in the environmental field. HAs could reduce the toxicity of a variety of organic pollutants or eliminate pollutants through photodegradation and adsorption. These pollutants include antibiotics, herbicides pesticides, fungicides, and other phenolic compounds. Additionally, HAs might be also used to treat heavy metal pollutants, such as mercury, copper, cadmium, uranium, and aluminum. HAs could adsorb heavy metals, thereby reducing their mobility in the environment and toxicity. HAs also have the potential to degrade microplastics and contribute to climate change adaptation. However, bibliometric analysis showed that the molecular structure of HAs remains unclear, thereby limiting clarification of mechanisms and further applications for decontamination. These findings highlight the interaction between HAs and the environment and offer critical insight to support further development of HAs for environmental applications. © 2022 Elsevier Ltd