Features of obtaining bentonite-based ceramic support using SLS 3D printing

Ceramic membranes based on natural clays are attractive for water treatment, yet their fabrication by selective laser sintering (SLS) remains largely unexplored. In this work, bentonite-based porous ceramic supports were produced by SLS of 65 vol% bentonite / 35 vol% polyamide-12 (PA12) powder mixture followed by thermal removal of the polymer. The SLS parameters were adjusted to obtain defect-free green bodies with anisotropic expansion relative to the CAD model (−4.6% to −8% in length, width and +33.3% in thickness), whereas subsequent sintering at 950°C yielded porous supports with net linear shrinkage of about 6–8.5% in-plane and almost no change in thickness. XRD and FTIR show that the layered montmorillonite structure is destroyed during firing and transformed into an amorphous aluminosilicate matrix with quartz as the main crystalline phase, while the disappearance of PA12 bands confirms complete binder removal. SEM/EDS reveal a transition from a plate-like aluminosilicate–polymer composite with intergranular macroporosity to a chemically homogeneous aluminosilicate ceramic with an open, interconnected macropore network (10–50 μm). TG/DSC analysis locates the main PA12 degradation between 400 and 600°C, defining the critical window for controlled binder burnout. Nitrogen adsorption–desorption demonstrates the evolution from a predominantly mesoporous green body with low pore volume to a mainly macroporous support with more than a twofold increase in total pore volume. These results demonstrate the feasibility of SLS for fabricating bentonite-based porous ceramic supports as precursors for functional ceramic membranes and provide a basis for further optimisation of composition, printing and sintering parameters. • First use of selective laser sintering (SLS) to fabricate bentonite-based ceramic supports. • Successful formation of a defect-free green body (composite) based on polyamide and bentonite using SLS technology. • Sintering converts a mesoporous green body into a predominantly macroporous ceramic support. • High potential of SLS technology to produce inexpensive bentonite-based ceramic supports with adjustable porosity.