Performance of geopolymer foams of blast furnace slag covered with poly(lactic acid) for wastewater treatment

This research investigated a new method to produce geopolymer foams from blast furnace slag (BFS) with poly(lactic acid) (PLA) covering the developed porosity into the materials. A porous alkali-activated material was developed, and a biodegradable polymer was used to cover the geopolymer in the bulk state. Geopolymer foams were synthesized with a sodium metasilicate solution, and the porosity was developed by adding hydrogen peroxide (H2O2). Foams of materials were produced with two stoichiometries of 1.4 and 1.6 g/L between solid/liquid with a hydrogen peroxide solution. The dimensional stability was achieved after coating geopolymer foams with PLA, improving the molding capacity on different geometries for the composite materials. Specimens of the geopolymer foam/PLA composites were characterized by X-ray fluorescence (XRF), Fourier transformed infrared (FTIR), thermogravimetry (TGA), and field emission gun scanning electron microscopy (FEG-SEM). The permeation analysis of metal oxide particles through the composites foam specimens was performed using water dispersions containing bismuth oxide or titanium oxide. The test resulted in high performance in the retention of particulate materials. The highlights of the results indicated the efficiency in the synthesis of geopolymer foam, a good formation of porosity, and an effective PLA coating on the internal interfaces of geopolymer foam through the development of a new bulk state coating method, improving the dimensional stability and the retention of bismuth and titanium oxides particles by the produced geopolymer foams for water depollution.