Development of ceramic hollow fiber from recycled quarry dust: exploring its properties as a support for ZIF-8 membrane in gas separation

Abstract

This work investigated the performances of ZIF-8 membranes coated on a low-cost ceramic hollow fiber (CHF) support developed from quarry dust (QD). The ceramic hollow fiber (CHF) was first fabricated using phase inversion and sintering techniques. The effects of the bore fluid flow rate (6–10 ml·min^− 1) and sintering temperature (1050–1150 °C) on the morphology and mechanical strength of the final CHF were systematically evaluated. A larger finger-like macrovoid structure was observed when a longer air gap distance was used. A higher sintering temperature enhances the mechanical properties of CHFs due to pore densification, but it also leads to a less porous CHF, which can affect their permeation flux. The relatively low sintering temperature needed for QD-based CHF (< 1150 °C) leads to a reduction in energy consumption, which is economically attractive for future commercialization. By controlling the ZIF-8 loading (0.4–1.6 wt%) in the coating solution, a uniform and well-coated ZIF-8 selective layer was coated to form a quarry dust ceramic hollow fiber membrane (QD-CHFM). A single gas permeation study was conducted at 2–6 bar, and it was observed that the permeability of gases was greater when the ZIF-8 loading was lower, particularly for CO₂ (1.19 × 10^− 4 cm³(STP)·cm·cm^− 2·s^− 1·cm^− 1·Hg^− 1). A further increase in the ZIF-8 concentration in the coating solution caused agglomeration, which simultaneously increased the path tortuosity. Therefore, the gas diffusion rate across the membrane decreased. The performances of ZIF-8/QD-CHFM were observed to be similar to those of other ceramic membranes available in the literature. This work indicated that ZIF-8 loading could significantly affect gas separation performance. In addition, reutilizing QDs as a raw material for ceramic membrane fabrication can help reduce disposal issues and reduce the overall cost of ceramic membranes for future development.