3D Printing of Hydrophobic Porous Materials and Their Application for the Adsorption of Organic Pollutants

Abstract

The effective removal of organic contaminants from both vapor and liquid phases is increasingly critical for industrial and environmental applications. These substances are typically toxic, resistant to degradation, and prone to bioaccumulation. Conventional methods often face challenges in efficiency, selectivity, and adaptability, underscoring the need for materials that can effectively remove such persistent organic pollutants across multiple phases. This work introduces an approach using digital light processing (DLP) 3D printing to engineer porous silica monoliths with tailored lipophilic properties. By incorporating hexamethyldisilazane into methacrylate-functionalized silica nanocage inks, we achieved uniform distribution of organic functionalities throughout the volume of the printed structures. This approach based on photo-cross-linkable nanoparticles eliminates the need for thermal postprocessing to gain pore accessibility, thereby preserving organic functionalities. The resulting materials feature high surface area (445 m2 g–1) and high affinity for organic compounds. These 3D printed materials demonstrated significant potential as sorbents for the capture of volatile organic compounds (VOCs) such as toluene, benzene, and cyclohexane, with high adsorption capacities (qe ≈1000–1200 mg g–1) and high selectivity (≈10) over water vapor. The materials also exhibit excellent cyclability, as evidenced by reversible adsorption and desorption processes following pseudo-first-order kinetics with fast adsorption (ka ≈0.02–0.06 min–1) and desorption (kd ≈0.1–0.3 min–1) rates. Similarly, these 3D printed sorbents can capture organics from liquid media, which was demonstrated here through the adsorption of Nile Red dye in hexane (qe = 2 mg g–1, ka = 2.2 × 10–3 min–1).