Chenxi Sui, Wantong Xie, Yujing Bian, Xiang Li
Heavy metal pollution poses a serious threat to water resource security and ecological health, due to its high toxicity, persistence, and bioaccumulation. Accordingly, it is crucial to develop efficient, low-cost, and environmentally friendly adsorption materials. Biomass-based materials, as a widely available, renewable, and low-cost natural organic resource, exhibit significant advantages for water pollutant adsorption and removal due to their unique porous structures and abundant active functional groups. This review systematically summarizes the classification strategies, fabrication methodologies, and adsorption performances of biomass-based materials for aqueous heavy metal ion removal. Key factors governing adsorption behavior, including solution pH, temperature, initial ion concentration, and adsorbent dosage, are critically analyzed to elucidate structure-property-performance correlations. Particular emphasis is placed on the underlying adsorption mechanisms, encompassing physical adsorption, surface complexation, ion exchange, electrostatic interactions, and synergistic interfacial effects. By integrating recent advances in material design and mechanistic understanding, this review provides a comprehensive framework bridging fundamental research and practical implementation, and highlights future opportunities for engineering next-generation sustainable biomass adsorbents toward efficient heavy metal ion decontamination.