Lower-temperature preparation of porous Al₂O₃ supports for O/W separation membranes by recycling mixed-dimensional attapulgite clay as sintering aid

Ceramic membranes have drawn attention in oil-in-water (O/W) treatment due to natural hydrophilicity and excellent chemical stability, however their application was restricted by high cost. In this work, a cost-effective Al₂O₃-based ceramic support was prepared at sintering temperature of 1500 °C with low-cost mixed-dimensional attapulgite (MDATP) as aid. The composite support with addition of 10 wt% MDATP and 3 wt% powdered carbon possessed an average pore size of 3 µm, bending strength of 63.7 MPa, pure water permeability of 1.32 × 10⁴ L·m⁻²·h⁻¹·bar⁻¹. Mullite was formed due to the reaction between Al₂O₃ and SiO₂ in MDATP during sintering, which played a key role in preparing support with corrosive resistance performance. Then, a superwetting microfiltration (MF) membrane with pore size of 0.18 µm and permeability of 1470 L·m⁻²·h⁻¹·bar⁻¹ was obtained by coating ATP nanofiber on the Al₂O₃-MDATP support with sintering temperature of 600 °C. The molecular dynamics results showed that the ATP can repel oil fouling with interaction energy of − 872 Kcal·mol⁻¹. The excellent O/W emulsion separation efficiency of the MF membrane further demonstrated the feasibility of ATP and its by-products in decreasing membrane cost and improving performance.