Τετάρτη 28 Ιουνίου 2017

Novel Nano Boehmite prepared by Solvothermal reaction of aluminum hydroxide gel in Monoethanolamine

Abstract

Solvothermal reaction of aluminum hydroxide gel (AHG) in monoethanolamine (MEA) was studied at several temperatures (100, 120, 150, and 200 °C) in several reaction times (2, 3, 4, 5, 6, and 13 h). The reaction product prepared at a low temperature of 120 °C in the reaction time more than 6 h gave a blue photoluminescence nanoboehmite intercalated with monoethanolamine derivatives (BM-MEA) in the colloidal solution, which showed a photoluminescence emission centered at 420 nm with an excitation of 360 nm. The powdery samples recovered from the reaction products were characterized by using elemental analysis, XRD analysis, IR spectroscopy, thermogravimetric (TG)-DTA, 13C and 27Al CP/MAS NMR spectroscopies, N2 gas adsorption/desorption isotherm, SEM and TEM images, and photoluminescence spectroscopy. The X-ray diffraction revealed that the basal space in BM-MEA was expanded from 0.61 to 1.2 nm by intercalation of MEA derivatives to boehmite, and the IR and 13C CP/MAS NMR spectra determined that the intercalated MEA derivatives are protonated- and carbamate-substituted MEAs, which are formed in the layers through a covalent bond with Al–OH groups on boehmite surface. The empirical formula of BM-MEA was estimated to be AlO(OH)0.82(OCH2CH2NH3+)0.05(OCH2CH2NHCOO)0.13 on the basis of the elemental TG-DTA and IR spectral analyses. We discuss the reaction mechanism of a unique blue photoluminescence BM-MEA formed by proceeding in CO2–H2O–alkanolamine system.

Graphical abstract

Possible structure model of BM-MEA.


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