Cost-effective Fuller’s Earth Ceramic Membranes for Treating Oil-Water Emulsion: Fabrication, Performance, Fouling, and Regeneration

Abstract

Ceramic membranes are increasingly used in wastewater treatment due to their excellent thermal, mechanical, and chemical stability. However, their widespread application was restricted by high production costs. This study describes the fabrication and evaluation of an economically viable fuller's earth clay (FEC)-based ceramic membrane for the dissolution of stable oil-water suspensions. A dry-pressing technique was used to fabricate the membrane, and then sintered at 850 °C. Functional groups and morphological features of FEC and the fabricated ceramic membrane were characterized using FTIR, XRD and SEM, respectively. The results show that the membrane is highly chemically stable, losing only 2.67 wt.% in acidic, and 0.54 wt.% in alkaline media, and a flexural strength of 36.6 MPa. In addition, the membrane’s shrinkage, porosity, mean pore radius, and permeability are found to be 11.5 %, 36.5 %, 0.85 µm, and 222.71 L m⁻² h⁻¹ bar⁻¹, respectively. A dead-end filtration set-up was used to study the flux at transmembrane pressures ranging from 0.69 to 2.75 bar, yielding a permeate flux of 15 to 110 mL, while oil rejection remained consistently high at 94.8-97.8% and COD removal reached up to 85.6%, confirming effective separation efficiency across all operating conditions. Significant reductions in TDS (up to 81%) and TSS (up to 95.6%) were perceived. Cake filtration was identified as the predominant fouling mechanism based on fouling behaviour analysis using the Hermia models, which is confirmed by optical microscopy examinations. The membrane regeneration studies showed a flux recovery ratio of 77% with good reusability. The developed low-cost ceramic membrane had an assessed fabrication price of around $53.5 per m² of membrane area, substantially lower than that of typical commercial ceramic membranes. Overall, FEC-based ceramic membranes offer a sustainable and cost-effective option for treating industrial oily wastewater.