Facile and low-cost method for preparing multilayer ceramic membranes based on cordierite and abundant clay: Application to dye removal

Textile dyes represent a growing source of environmental pollution worldwide, affecting aquatic ecosystems and, by extension, human health. This study aims to develop low-cost ceramic membranes for the treatment of water contaminated by these dyes, using natural and economical materials. The membranes were made from abundant clay with different mass percentages of magnesium hydroxide, used as a pore-forming agent and were sintered at 900 °C and 1000 °C. To enhance filtration performance, the membranes were coated with a chemically, physically, and thermally stable layer of refractory cordierite phase. This was achieved using a sedimentation technique, which allowed precise control overthe thickness and ensured the formation of a thin, homogeneous layer. The microstructural evolution of the membranes was examined using XRF, XRD, SEM, and DTA-TGA techniques, while their properties were assessed through measurements of flux, permeability, porosity, density, and mechanical strength. Filtration performance was evaluated using a methylene blue solution. The results indicated that membranes sintered at 900 °C effectively filtered 99 % to 99.8 % of dyes, achieving fluxes between 46.36 and 84 L/(h·m²), with mechanical strengths ranging from 79 to 113 MPa. For membranes sintered at 1000 °C with 5 % magnesium hydroxide, filtration performance improved from 50 % to 99 % with the addition of a cordierite layer, resulting in fluxes between 61 and 77 L/(h·m²) and compressive strengths from 60 MPa to 136 MPa. Production costs for ceramic membranes are estimated at around 12 to 46 USD/m², due to the use of low-cost materials and reduced sintering temperatures. The incorporation of the cordierite layer enhances the membranes’ suitability for demanding environments.