Preparation, characterization and application of geopolymer-based tubular inorganic membrane

Abstract

Inorganic membrane (IM) has been widely concerned in the fields of water filtration and gas treatment. Compared to ceramic and organic membrane, geopolymer inorganic membrane (Geo-IM) has a good application prospect in many fields due to their low cost and excellent properties. In this paper, a green, environmental-friendly, fine performance and controllable pore structure tubular inorganic membrane prepared by using cheap slag reinforced metakaolin based geopolymer can be used for water filtration and flue-gas treatment. The experimental results show that the compressive strength and flexural strength of the sodium based Geo-IM are increasing from 7 MPa and 1.37 MPa to 14 MPa and 2.12 MPa respectively. In other word, the compressive strength and flexural strength of potassium based Geo-IM were increased by 100% and 54.74% respectively compared with that of sodium based Geo-IM, it is helpful for the inorganic membrane to withstand certain pressure. The thermogravimetric (TG) analysis showed that the potassium based Geo-IM has good thermal stability. By measuring the compressive strength of the IM at 0–1000 °C, it can be seen that the potassium-based inorganic membrane (K-WG-IM) can withstand the temperature of 800 °C. The specific surface area of K-WG-IM is about 77 m2·g−1, the porosity is about 70%, and the water flux is 100–8000 kg·m−2·h−1 (25 °C, 1 MPa). The filtration performance of the Geo-IM was characterized by the self-made water filtration and flue-gas treatment device in the laboratory. It is found that the Geo-IM could capture particulate matter (PM) with particle size greater than 1.67 μm in carbon black aqueous solution, and the removal rate of PM2.5 in flue-gas was as high as 97%, and the removal rate was still above 90% when the flue-gas temperature reached 600 °C. In a word, the tubular Geo-IM with low-cost, high-efficient and green properties has considerable potential in the practical applications.