Lignin Agricultural as a Biosorbent for Metal Ions: Mechanisms and Water Treatment Applications

Abstract

            Water contamination by metal ions and the major issue of water hardness continue to affect domestic, agricultural, and industrial water supplies. Conventional treatment methods, such as membrane filtration, ion exchange, and chemical softening, are too costly and may generate secondary waste, which limits their long-term sustainability. As a result, increasing attention has been given to low-cost and green, eco-friendly alternatives for water treatment. Lignin is a naturally occurring polymer obtained in large quantities from agricultural waste and industrial by-products. Because of its abundance, low cost, and chemical stability.  Lignin has emerged as a promising biosorbent for the removal of metal ions from aqueous systems. Lignin acts like magnets. Its surface contains functional groups such as phenolic, hydroxyl, carboxyl, and methoxyl groups, which are known to interact with metal ions through ion exchange, surface complexation, and electrostatic interactions.