Effects of sintering temperature on the filtration and mechanical properties of ceramic water filters

This paper presents the results of a combined experimental and theoretical study of the effects of sintering temperature on the mechanical and filtration properties of clay ceramic water filters (CWFs). CWFs produced from 50:50 volume proportion mixtures of clay and sieved sawdust (porogen) were sintered at 850 degrees C, 900 degrees C and 950 degrees C to produce micro- and nano-porous structures. The sintered clay structures were then characterized using X-ray diffraction and scanning electron microscopy. The flow and filtration characteristics of the filters were then elucidated using a combination of theory and fluid flow experiments, before exploring the effects of porosity on E. coli removal and flow rates through the filter. The E. coli removal efficiency is shown to be inversely proportional to the sintering temperature, with log removal values (LRV) of 4.89, 4.59 and 4.46 for the CWFs sintered at 850 degrees C, 900 degrees C and 950 degrees C, respectively. The paper also examines the effects of sintering temperature on the compressive and flexural strengths, as well as the fracture toughness of the CWFs. The compressive strengths of the CWFs increased (between 6.55 and 7.02 MPa), whereas the flexural strengths (between 3.05 and 2.22 MPa) and the fracture toughness values (between 0.21 and 0.14 MPa root m) both decreased in response to the increased porosities induced by the increased sintering temperature. The underlying fracture and toughening mechanisms are then elucidated before discussing the implications of the results for the fabrication, transportation, and handling of robust ceramic water filters.