Study on soil heavy metal contamination and its remediation using lignin-based adsorbents: A review
Fangqi Guo, Xiaojun Hu, Xiaotong Zhang, Yueyi Chen, Jinju Hou
Abstract
Intensified by economic expansion and urban development, heavy metal contamination in soil poses significant risks to food safety and environmental well-being, necessitating the deployment of efficacious remediation methods. Lignin, a biocompatible, renewable organic polymer of substantial molecular weight and functional versatility, is harnessed to fabricate effective adsorbents through a series of modifications tailored for these challenges. This investigation offers a thorough exposition on the prevalent conditions, origins, and hazards associated with soil heavy metal contamination, presenting a systematic categorization of human-induced sources such as industrial operations, wastewater irrigation, and vehicular emissions. It examines the soil remediation techniques, particularly highlighting the capabilities of lignin-derived adsorbents, and delineates their manufacturing processes, which encompass prevalent methods of lignin extraction and modification. Moreover, the utilization of lignin-based adsorbents in mitigating soil heavy metal pollution (HMP) is elaborated. Discussions include the adsorptive properties, mechanisms, kinetics, and thermodynamic models applicable to lignin-based adsorbents under varied environmental conditions. Furthermore, investigations into the reusability of lignin-based adsorbents are underscored to augment their economic viability. Conclusively, this review identifies the existing challenges and deficiencies in the development of lignin-based adsorbents and calls for advanced refinement of modification techniques to enhance their adsorptive efficacy and expand their application spectrum.