Comprehensive characterization, development, and application of natural/Assam Kaolin-based ceramic microfiltration membrane

Abstract

In this work, a natural Kaolin clay collected from Deopani area in Karbi Anglong district of Assam, India, was characterized in detail to see its feasibility in ceramic membrane fabrication and further application. The clay was characterized using X-ray fluorescence, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and particle size distribution (PSD). Five different membrane compositions were chosen by varying the amount of Kaolin and binders such as sodium carbonate, boric acid, and sodium metasilicate. The raw material mixture was characterized by TGA and PSD. The X-ray diffraction analysis, average porosity, chemical stability, flexural strength, surface morphology, pore size distribution, and water permeability of the membranes were investigated. The porosity of sintered membranes was in the range of 21.5–34.5%. It was observed that the pore size decreased whereas flexural strength increased with decrease in Kaolin percentage and increase in binder percentage, respectively. The average porosity, pore size, and flexural strength of the membrane with higher water flux were 34.5%, 2.28 μm, and 7.1 MPa, respectively. The maximum permeability obtained was 6.12 × 10−9 m Pa−1 s−1. This membrane was selected for microfiltration of methylene blue dye. The membrane had negative charge at the pH range of 3–11, implying adsorption as the removal mechanism for the cationic dye. The dye removal for 10 mg L−1 feed concentration was 99.07% which decreased to 93.45% for 100 mg L−1 at 1.5-bar transmembrane pressure. The prepared low-cost ceramic membrane showed good promise to be used in dye removal and other membrane applications.