Self‐Thickening and Self‐Strengthening 3D Printing Magnetic Cellulose‐Based Aerogel for Adsorption and Recovery of Methylene Blue

Abstract 3D printing of biomass has attracted increasing attention and can meet the requirements of various practical applications. Herein, 3D printing of a cellulose‐based aerogel is achieved by direct ink writing based on a self‐thickening and self‐strengthening strategy, followed by freezing drying. The magnetic cellulose‐based aerogels (MCAs) containing Fe₃O₄ nanoparticles are ideal adsorbents for adsorbing and removing organic pollutants from water. As catchers and carriers for magnetic removal, MCAs (Fe₃O₄ nanoparticles and cellulose) provide large active sites, which allows organic pollution to be quickly and stably bound on the surface. The adsorption effect of methylene blue (MB) is dependent on pH and the removal efficiency of MB (5.6 mg l^‐1, pH = 9) is 88.5% for MCA, which occurs almost instantaneously at room temperature. In addition, the collected aerogel‐MB hybrid can be reactivated by acid‐washing (pH = 3) without obvious changes in the adsorption performance of MCA. The MCA exhibits a fast, efficient and sustainable removal of organic pollutants, which provides an inexpensive and recyclable method for water remediation.