Facile Mixing Process to Fabricate Fly-Ash-Enhanced Alumina-Based Membrane Supports for Industrial Microfiltration Applications

Ceramic membranes with satisfactory chemical stability and high mechanical strength have wide chemical industrial applications in treating wastewater at harsh conditions. However, the ceramic supports usually need to be sintered at high temperatures to provide high mechanical strength for the ceramic membranes, thus requiring higher energy consumption. Herein, "ball effect"of spherical fly ash particles (as sintering aids) has been put forward to simplify the mixing process among the alumina powders and decreased the sintering consumption of ceramics without a ball milling process, thereby facilitating the fabrication of tubular ceramic supports for industrial applications. The liquid phase sintering mechanism has also been discussed from three aspects, including sintering temperature, fly ash loading, and holding time. After that, ceramics with high bending strength and high permeability were successfully prepared, and thus used as the supports for fabricating ceramic microfiltration (MF) membranes (with a permeability of 1.2 m3 m-2 h-1 bar-1 and a pore size of 150-200 nm). The MF membranes also showed a great potential to treat industrial spent tin wastewater from printed circuit boards. This study provides comprehensive research on analyzing the mixing mechanism and liquid phase sintering mechanism of ceramic supports and promotes the actual industrial applications.