Fabrication and characterization of industrial fly ash ceramic membranes for efficient removal of methylene blue dye

This study presents the development of a cost-effective ceramic membrane derived from waste inorganic fly ash for efficient dye removal from aqueous solutions, leveraging the synergistic properties of fly ash and a supporting substrate through a combination of chemical grafting. A wider particle size distribution of fly ash results in a denser membrane structure with reduced porosity. The membrane was fabricated using the uniaxial pressing technique, specifically through dry uniaxial compaction, and was analyzed using Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA). Additionally, porosity and permeability tests were conducted using pure water. The particle size of fly ash significantly affects the properties of the ceramic membrane, including porosity, surface area, mechanical strength, and filtration efficiency. The membrane featured varying compositions and sintering temperatures ranging from 600 °C to 900 °C. The porosity of the membranes was found to be 31.31 %, with an average hydraulic pore radius of 0.311 µm, leading to an increase in pure water flux from 0.022 to 0.15 L/m 2 min bar within a transmembrane pressure range of 1–4 kg/cm 2 . The membrane surface displayed a negative charge within the pH range of 4–12, indicating that adsorption played a key role in removing the cationic dye. This work emphasizes the significant potential of these membranes for treating dye-containing aqueous solutions, considering factors such as transmembrane pressure, feed concentration, flux, and rejection. At a pressure of 1 kg/cm 2 , the highest dye removal efficiency is 99.86 % at a feed concentration of 20 mg/L.