Green synthesis of high porosity waste gangue microsphere/geopolymer composite foams via hydrogen peroxide modification

A novel coal gangue microsphere/geopolymer composite foam (CGM/KGP) was firstly synthesized by adding coal gangue microspheres (CGM) into geopolymer foams. Effects of coal gangue microspheres, foaming agent (H2O2) and stabling agent (SDS) on the microstructure, pore structure and mechanical properties of CGM/KGPs were investigated. The CGM/KGPs were composed of amorphous phase with some peaks of microshpheres. CGMs were dispersed and bonded well with the geopolymer matrix. Total and open porosity of M4H5S3 samples reached maximum value of 88.3 vol% and 80.5 vol%, respectively. Compression strength of CGM/KGPs reached the maximum value of 5.70 +/- 0.88 MPa for the M4H1S3 sample. The increasing addition of H2O2 led to the decrease strength of pure foams and CGM/KGPs. Moderate surfactant (SDS, 3 wt%) contributed to the formation of homogeneous cell size and porosity in the composite foams. The novel geopolymer composite foams have potential applications in membrane supports, catalysis and filtration fields. (C) 2019 Elsevier Ltd. All rights reserved.