Synthesis of Metakaolin Acid-based Geopolymers for Dye Removal

Textile industry and dye-containing wastewater is worldwide pollution problems. The residual dyes contained organic pollutants to natural water resources or wastewater treatment systems. The discovery of geopolymers has been a breakthrough in the field due to its amorphous and porous structure. The objectives of this research are to synthesize and characterize metakaolin (MK) phosphorous acid-based geopolymers using different SiO2/Al2O3 ratio.The optimum ratio of silica to alumina was furthered study by added different percentage of pore-forming agent. Raw material, kaolin was calcined to produce metakaolin which was then mixed with H3PO4, distilled water, alumina oxide/ silica oxide powder to produce slurry mixture. The mixture was then cured 80 ̊C for 24 hours. Different properties of geopolymers have been characterized for its particle size and porosity. The solubility test was conducted and the best geopolymer was chosen to be modified by pore-forming agent to increase the porosity. Adsorption experimental test on dye solution was conducted by varying the adsorbent dosage, pH and contact time. The optimum silica to alumina ratio of the geopolymer was the GP-R2.4 that gave the highest percent removal of 90%. Meanwhile, study on addition of pore-forming agent showed an optimum of 3% pore-forming agent in the geopolymer gave the highest percent removal of 100%. Meanwhile the optimum pH value for adsorption test is 10 and the increment in the adsorbent dosage usage increased the percentage of removal. The adsorption activities for both with and without pore-forming agent fitted the pseudo second order kinetic model. Besides, the adsorption study for both with and without pore-forming agent found to be fitted into the Langmuir Isotherm model.