A green phosphate-based geopolymer adsorbent or binder with high specific surface area for environmental applications

Abstract

High water content mud has complex chemical composition and high water content, making it difficult to be directly utilized in engineering. However, its high clay content, small particle size, and large specific surface area may make it possible to prepare a adsorbent or binder with high specific surface area for environmental applications. This study attempts to prepare a phosphate-based geopolymer (PGEOs) adsorbent or binder with high specific surface area using aluminum dihydrogen phosphate as the activator, high water content mud powder and fly ash as raw materials. The microstructure of PGEO was invsetigated using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and N2 adsorption/desorption experiments. The results showed that the PGEOs belong to mesoporous materials, and has the maximum strength (9.06 MPa) at 28 days when the mud powder content was 10 %. Moreover, the specific surface area of the PGEO increased significantly with an increase in mud powder content, at 7 days of curing, when the mud powder content increases to 50 %, and the specific surface area increased from 42.074 m 2/g to 311.660 m2/g. which are significantly higher than many existing adsorbents. Therefore, the PGEOs prepared with mud powder and fly ash has great potential in pollutant adsorption and solidification/stabilization treatment in future.