Local Diatomaceous Earth from Kapatagan, Northern Mindanao, Philippines: A Micro/Nanoporous Siliceous Additive for Ceramic Wall Tile Production

Advancements in micro/nanomineral-based materials are driving innovations in sustainable ceramics. This study explores the potential of locally sourced diatomaceous earth from Kapatagan, Lanao del Norte, Philippines, as a micro/nanoporous siliceous additive for improving the performance and sustainability of commercial ceramic wall tiles. The Kapatagan diatomaceous earth (KDE) exhibited notable physicochemical characteristics, including 52.49% water absorption, 19.28% fired shrinkage, 0.92 g/cm³ bulk density, and 48.79% apparent porosity. Scanning electron microscopy revealed the presence of intricate, porous diatom frustules that retained micro/nanostructured features even after sintering. X-ray diffraction (XRD) analysis indicated the presence of hematite and quartz in the raw KDE, with the transformation of phases to cristobalite and quartz upon sintering at 1150 °C.
Incorporating 5 wt.% KDE into a standard wall tile body (T5), sintered at 1235 °C, led to an increase in water absorption (0.48%) and apparent porosity (0.80%), while reducing fired weight (66.92 g) and bulk density. The microstructural evolution of T5 showed modified interparticle porosity, causing a slight decrease in the modulus of rupture (6.03 MPa). The XRD pattern of T5 confirmed quartz and cristobalite as the dominant crystalline phases. A control tile (T0, without KDE) was also fabricated for comparison.
These findings demonstrate the promising role of local diatomaceous earth as a sustainable micro/nanoporous siliceous additive, highlighting its contribution to the emerging field of micro/nanomineral-based materials for advanced and lightweight ceramic applications.