Lignin for metal ion remediation in aqueous systems

This chapter deals with the pollution of aquatic environments due to heavy metals and the use of lignin to remediate water-contaminated environments. Firstly, aspects of their toxicity, content in the environment, and remediation technologies are presented and discussed. Particular emphasis has been made on the use of lignin and its derivatives to remediate polluted water with a double benefit: to prompt effective solutions to restore polluted water and use a natural material that otherwise could impact on the environment, being lignin biomass produced in high amounts, often burned regardless of the value of this precious material. We demonstrated that lignin that does not have specific selectivity for complex polluted water can be chemically modified, promoting at the same time adsorption capability, stability, selectivity, and recyclability. Lignin chemical modification that gives desired physical, chemical, and mechanical properties is crucial to achieving hydrophilicity, hydrophobicity, and broadening pollutant kinds for efficient removal. Analysis of the published literature also confirmed that the development of nanoscaled lignin-based adsorbents is under investigation and could represent the advanced solution in the coming decades.