Structural and characterization assessment of clay ceramic water filter materials from locations near the Thar Desert in India

The physical and chemical characteristics of the clay are highly dependent on the geospatial conditions. Clays procured from three geospatially distinct locations (Raithal in Jalore District, Rajasthan, India; Gajsinghpura and Jheepasani in Jodhpur District, Rajasthan, India) near the edge of the Thar Desert in India have been used in this study. Frustum-shaped 3L green composites were prepared by a three-step process by mixing clay and sawdust in equal volume fractions, similar to local G-filters in India. Here, green composites were sinter-fused at various temperatures to create ceramic water filters. Raithal and Gajsinghpura clay-based ceramics showcased similar behavior in grain length variation while being sintered at 650°C, 750°C, and 850°C, respectively. Further, the pore dimensions, thermal stability, fracture toughness, and flow characteristics of these ceramic water filters baked at 750°C were studied. The gravity-based cumulative water discharge rate proportionally increased with the pore surface area of distinct ceramics from different locations. Micro-CT (3.4 m resolution) data visually confirms that Gajsinghpura clay has a rigid structure with a large pore volume. Results from thermogravimetric analysis showcase the reorganization of the gibbsite layer in Jheepasani clayey soils. Crystalline and amorphous characteristics were observed from micrographs of Gajsinghpura and Raithal ceramic samples. Raithal clay ceramic frustum bases were the toughest. Gajsinghpura and Raithal clay-based ceramic filters show similar behavior in Escherichia coli removal as a function of average pore diameter.