Modification of ceramic membranes porosity using layer deposition of kaolinite and palygorskite

Ceramic membranes with high permeability can only be obtained in an asymmetric multilayer configuration with a macroporous support, which provides mechanical strength and lowers flow resistance. In this work, two clay soils, commercial kaolin (K) and a Moroccan natural material (P3), were used for the deposition due to their mineralogical composition rich in kaolinite and palygorskite respectively. The novel aspect of this work is the use of a 2-μm fraction of the two submentioned materials (K and P3) as a deposit on the cylindrical membrane supports comprised of anorthite, cordierite, and spinel powders to decrease the large pore size generated by the decomposition of the used pore-forming agent (Corralina Officinalis Algae). This latter showed an important and large granulometry due to the coarse grains of the algae. The layer deposition process on the elaborated membrane supports was dip-coated using different suspensions (solid ( wt.%), liquid (dispersant/distilled water ratio up to 3)). To determine the conditions for an optimum deposition efficiency, the effect of the clay concentration in the deposition suspensions and the immersion time (up to 6.5h) were discussed. It was found that the suspension containing 2% of clay with 2h of soaking time allows to increase adhesion strength which means that no cracks or defects were observed on the surface of the manufactured membranes. Decrease in the concentration of methylene blue that was used to prepare the filtrated solutions. Filtration tests were carried out and the absorbance of the filtered solutions was measured by UV-Vis and thus showed a significant decrease in their concentrations (0.021 mg/L).