A Na-P zeolite was synthesized and subjected to ion exchange with Ca2+, Cu2+, Al3+, and In3+, and supported with H+/NH4Cl (NH4-P) by in situ reaction of EtOH and NH4Cl. All the exchanged zeolites showed catalytic activity in the ABB’ Povarov reaction. However, zeolite NH4-P promoted a better yield. In all reactions two products were obtained, 2,6-dimethyl-4-(2-oxopyrrolidin-1-yl)-1,2,3,4-tetrahydroquinoline and 1-(1-(4-methylphenylamino)ethyl)pyrrolidin 2-one. Synthesis using zeolite P as catalyst proves to be a simple method with high yields, short reaction times and easy preparation. The catalyst can be recovered by filtration and reused up to three times in good yields.
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.
In this study, bentonite geopolymer was used as a sorbent to remove methyl violet in aqueous solutions. Several parameters such as pH, sorbent dose and initial sorbate concentration were evaluated. The greater sorption effectiveness of bentonite geopolymer is observed at pH 2-3, and the greater sorption capacity of methyl violet by bentonite geopolymer occurs when the sorbent/sorbate ratio decreases. The study of sorption kinetics showed that the data fit the pseudo-second order model, where much of the sorption occurs during the first hour of contact, it was shown that the process prefers diffusion between pores. Sorption was adjusted to the isotherm of Langmuir, which indicated that the sorption is preferentially in monolayer. bentonite geopolymer proved to be an excellent candidate for removal of methyl violet in aqueous bodies.
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