In this work a geopolymeric material was synthesized by alkaline activation of calcined coal gangue at 700 °C using a solution 1:9 of NaOH:Na2SiO3, as a sorbent to remove rhodamine B from aqueous solutions. X-ray diffraction, fourier-transform infrared spectroscopy and scanning electron microscopy were used to characterize the material structurally and morphologically; removal efficiency and rhodamine B sorption capacity were evaluated by using ultraviolet-visible spectrophotometry. Sorption tests were performed to evaluate the effect of the dose of geopolymeric material and the contact time of this material with rhodamine B solution in a range from 0.5 to 30 hours, interval in which the best sorption was observed. Removal efficiencies and sorption capacity to 80.4% and 1.035 mg/g respectively were found, these values show the usefulness of the material for the removal of rhodamine B in aqueous solution, making it an interesting alternative for water decontamination and object of study for future works. Removal efficiency increased by increasing geopolymer dosage and contact time.
In this work, coal gangue from the department of Cesar, Colombia, was used in the synthesis of a geopolymer by alkaline activation. The effect of the variation of the geopolymerization temperature and of four parameters on the composition of the activating solution was evaluated: SiO2/Al2O3, SiO2/Na2O, NaOH concentration and amount of H2O2. The geopolymer was characterized structurally by X-Ray diffraction and Fourier transform infrared spectroscopy. The sorption properties of methylene blue in aqueous solutions of geopolymer were studied through ultraviolet-visible spectrophotometry. Effects of various parameters such as pH value, geopolymer dose and initial concentration on the sorption capacity were studied. The adsorption kinetics and adsorption isotherm fitted well with the pseudo-second order model and Langmuir model, respectively. In the kinetic study it was evidenced that the adsorption equilibrium time was reached quickly, therefore this material constitutes a viable alternative for water decontamination.
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