A porous gradient geopolymer-based tube membrane with high PM removal rate for air pollution

Abstract

Existing technology does not meet the urgent need for a cheap and efficient particulate matter (PM) removal filter. In this work, a porous gradient geopolymer-based tube membrane was successfully prepared using one-step molding. The microstructure, mechanical properties and permeability of the tube membrane were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury injection, compressive strength tests, and pressure gauge measurements. The PM removal capacity of the membrane was studied using a particle counter and TG-DSC analysis. The process and mechanism of PM removal were studied using SEM and EDS. The results show that the porous gradient structure of the membrane can be controlled by adding different contents of foaming agent and adjusting the interface properties between a geopolymer paste and a mold surface. In this work, the tube membrane with an optimal content of 0.9 wt% H2O2 showed better mechanical properties and a lower pressure drop than the other samples. Moreover, the PM filtration experiments demonstrated that the tube membrane can achieve a high PM2.5 removal efficiency from 96.5% to 98.7%, a PM10 removal efficiency from 98.0% to 99.5% and good recycling performance. Therefore, the porous gradient geopolymer-based tube membrane may have positive potential applications for PM removal from air pollution.