Desenvolvimento e caracterização de membranas cerâmicas de cordierita.

Abstract

Membrane separation processes are in full development today. Ceramic membranes find wide application, especially in processes whose working temperatures are above 250 ° C, as well as in separation of solutions in which the pH is extremely acidic or even when organic solvents are present in the system. In contrast, the ceramic membranes They have the disadvantage of having a high cost of implementation, thus requiring a large initial investment due to the high price of membranes. For this reason, currently, the main focus of concern in membrane development aims to optimize production costs by finding ceramic raw materials at more competitive prices, such as cordierite, in addition to more efficient production processes. such as extrusion. This work consisted in the fabrication of cordierite tubular membranes formed by the extrusion process, using four different sintering temperatures, aiming to show the influence of these temperatures on the membrane characteristics. The membranes were sintered at 1150, 1200, 1250 and 1280 ° C, with a constant 60 min plateau. It was observed that as the sintering temperature increased, there was an increase in membrane shrinkage. The mass X-ray diffraction test was performed after sintering and the result showed the formation of cordierite in the four sinterings performed, proving that the composition of the mass made through low cost minerals, such as clay, bentonite. and talc, cordierite form after sintering. Regarding the membrane pore size and distribution, the results of the SEM and porosimetry tests using mercury intrusion showed the presence of pores, with sizes of 1.4; 2.2; 3.3 and 4.1 µm and porosity of 28.7; 29.1; 27.7 and 24.3% at temperatures of 1150, 1200, 1250 and 1280 ° C, respectively, characterizing them as microfiltration membranes. Tangential flow tests with distilled water showed that the sintered membranes at 1280 ° C had the highest flow, followed by 1250 ° C, 1200 ° C and finally 1150 ° C. The average flux values ​​found in the sintered membranes at temperatures of 1150, 1200, 1250 and 1280 ° C were approximately 68, 143, 378 and 587 kg / h.m2 respectively, after stabilization. Regarding the application of membranes in the water treatment of the Sucuriju river, it was found that the turbidity of the water was reduced from 311 NTU to values ​​close to zero for all membranes studied. It was also found that the flux was greatly reduced, and the highest relative flux was observed for the sintered membrane at 1250 ° C.