Research Progress on Cellulose Nanofiber (CNF) and Its Derivatives in Heavy Metal Wastewater Treatment

Heavy metal water pollution is characterized by high toxicity, bioaccumulation, and difficulty in natural degradation, making it a key challenge in water pollution control.Traditional heavy metal wastewater treatment technologies suffer from drawbacks such as high cost, significant secondary pollution, and large solid waste generation.Cellulose nanofiber (CNF), derived from agricultural and forestry biomass resources, possesses outstanding advantages such as large specific surface area, abundant surface hydroxyl groups, biodegradability, and ease of surface functionalization, making them a promising class of green bio-based adsorbent materials.However, primitive CNF rely solely on hydroxyl groups for heavy metal adsorption, resulting in limited adsorption capacity and poor wet structural stability, which restricts practical engineering applications.This paper reviews the structural characteristics and main modification strategies of CNF and its derivatives, summarizing modification methods such as carboxylation, amino grafting, inorganic hybridization, and cross-linking and composite formation.It elucidates the adsorption mechanism of CNF-based materials for removing heavy metal ions, analyzing the effects of pH, ionic strength, temperature, and competing ions on adsorption behavior.The paper summarizes the current application status of 2D membrane materials and 3D aerogel/hydrogel materials in the field of heavy metal wastewater treatment.It discusses the current limitations of these materials, including insufficient wet mechanical properties, poor selectivity, and difficulties in large-scale preparation.Finally, it looks forward to the future development direction of CNF-based adsorbent materials, providing theoretical reference for the development of biomass-based water treatment adsorbents.