CTAB-Assisted Surface Immobilization of Silver Nanoparticles onto Porous Ceramic: Effects of Reducing Agents and Soaking Time

Porous ceramic pellets (PCPs) coated with silver nanoparticles (Ag NPs) have attracted considerable attention as surface-modified ceramic materials because they combine the structural stability of porous ceramics with the unique physicochemical properties of Ag NPs. In this work, the PCPs were prepared from local Thai clay, and Ag NPs were immobilized onto the PCP surface using cetyltrimethylammonium bromide (CTAB) as the surface immobilization. The effects of ceramic composition, reducing agents, and soaking time on the surface immobilization of Ag NPs were systematically investigated. The optimal ceramic composition consisting of 65 wt% red clay, 25 wt% ceramic powder, and 10 wt% rice husk exhibited good structural stability after soaking and a porosity of approximately 35%. Ag NPs were synthesized in situ using ascorbic acid (AA) and sodium borohydride (NaBH4) as reducing agents, and coating performance was examined at soaking times of 6, 12, 24, and 48 h. FE-SEM observations revealed that Ag NPs synthesized using AA tended to form relatively large agglomerates, whereas NaBH4 produced a more homogeneous nanoparticle distribution on the PCP surface. Among the investigated conditions, NaBH4 with a soaking time of 12 h exhibited the most homogeneous nanoparticle distribution. These results suggest that CTAB-assisted surface immobilization is an effective strategy for immobilizing Ag NPs on porous ceramic substrates. The present study primarily focuses on surface immobilization behavior rather than biological performance.