This study demonstrates the preparation of porous geopolymers using different foaming agents for dye removal in water using methylene blue as the model solution. The porous membranes were prepared by combining alkaline activation solution, aluminosilicate source (either clay-rich laterite or iron-rich laterite), amorphous silica (rice husk ash) with direct foaming (with either H2O2 or Al powder), followed by curing first at room temperature for two hours, then at 65°C for another two hours. The physical properties such as apparent porosity, bulk density, water absorption and stability in water were obtained to select porous geopolymer suitable for filtration. Results shows that the best porous geopolymer suitable for filtration were those prepared using hydrogen peroxide as foaming agent and have a rice husk content of ≤ 20%. Permeability test carried out on the selected foams revealed that they were not permeable, so there was need to optimize the foams. Three different surfactants were used for the optimization (stabilization) of the foams. Based on screening through permeability tests, the triton H66 surfactant was selected for use. The physical properties of the optimized selected foams showed an augmentation of these properties for a foam. This augmentation was seen to be influenced by the rice husk ash content in the matrices, with the augmentation increasing with rice husk ash content. Two optimized samples (one from each base material) was applied in methylene blue removal in a filtration column experiment. After 8 hours of collecting effluent, it exhibited a removal efficiency of approximately 97%. This efficiency reduced to 95% with the rice husk ash content of over 20% in the matrices. The membranes methylene blue removal potential was determine with an infrared spectroscopic analysis. The new peak at 395 cm-1 affiliated to C-N-C of methylene blue confirms the presence of adsorbed methylene blue in the matrices. The results obtained demonstrates that porous filters in this study can be potentially used in industrial and domestic wastewater treatment.
Published Date: 2023-03-02; Received Date: 2022-11-19