Low-Cost 3D-Printed Kaolin–Rice-Husk Microporous Membranes for Microplastic Removal: A Comparative Study with a Commercial Ceramic Membrane

Microplastics (MPs) are pervasive emerging contaminants in freshwater and drinking-water systems, and conventional treatment processes may achieve insufficient removal of smaller MP fractions. Membrane filtration provides an effective barrier to MPs; however, commercial ceramic membranes can be relatively expensive. In this work, low-cost porous ceramic membranes were fabricated by extrusion-based three-dimensional (3D) printing of a kaolin–rice husk paste, followed by sintering at 1200 °C. The removal of model spherical polyethylene (PE) and irregularly shaped polyethylene terephthalate (PET) MPs across different particle-size fractions was evaluated using dead-end filtration and benchmarked against a commercial ceramic membrane. The 3D-printed membrane removed 58.3 ± 3.6% of 1–10 µm PE particles, while complete removal was achieved for the 75–90, 300–355, and 600–710 µm PE fractions. For PET, removal efficiencies of 80.8 ± 0.9%, 94.9 ± 1.8%, and 100% were obtained for the 10–45, 45–75, and 75–150 µm fractions, respectively. By comparison, the commercial membrane achieved 100% removal across all PE and PET fractions tested. The fabricated membrane had a modal pore size of 0.80 µm and an estimated cost of USD 2.98, compared with USD 54.45 for the commercial 0.45 µm membrane. Thus, the 3D-printed membrane effectively removed medium and large MP fractions, while its estimated fabrication cost was approximately 94.5% lower than the purchase cost of the commercial membrane used for comparison. Although its larger pore size resulted in incomplete removal of the smallest MP fractions, the combination of effective removal of larger MPs and substantially lower estimated fabrication cost demonstrates the potential of extrusion-based 3D printing as an alternative approach for producing ceramic membranes for MP removal.