Additive Manufacturing and Functionalization of Hollow Polypropylene Sorbents for Water Remediation

As the demand for clean water intensifies, developing effective methods for removing pollutants from contaminated sources becomes increasingly crucial. This work establishes a method for additive manufacturing of functional polymer sorbents with hollow porous features, designed to enhance interactions with organic micropollutants. Specifically, core-shell filaments are used as the starting materials, which contain polypropylene (PP) as the shell and poly(acrylonitrile-co-butadiene-co-styrene) as the core, to fabricate 3-dimensional (3D) structures on-demand via material extrusion. After 3D printing, the cores of the printed roads are removed through solvent extraction, creating hollow structures that increase accessible surface area for adsorption. Subsequently, a sulfonation-induced crosslinking reaction installs sulfonic acid functionalities into the PP backbones, while enhancing their chemical stability. It is found that larger voids, and thinner polymer shells, enable improved structural retention during the sulfonation through limiting reaction-induced stresses. The hollow sulfonated PP sorbents exhibit a strong affinity against cationic pollutants. Specifically, larger voids within these structures not only improve structural integrity but also result in accelerated adsorption kinetics by maximizing accessible surface area, thereby enhancing pollutant removal efficiency. This work provides a promising solution for advanced structured sorbent fabrication with hollow architectures, leading to more effective solutions for water contaminant removal in the future.