Investigation of thermal behavior of layered double hydroxides intercalated with carboxymethylcellulose aiming bio-carbon based nanocomposites

Abstract

Carboxymethylcellulose (CMC), a polymer derived from biomass, was intercalated into layered double hydroxides (LDH) composed by M2+ /Al3+ (M2 Al-CMC, M = Mg or Zn) and evaluated as precursors for the preparation of biocarbon-based nanocomposites by pyrolysis. M2 Al-CMC hybrids were obtained by coprecipitation and characterized by X ray diffraction (XRD), vibrational spectroscopies, chemical analysis, and thermal analysis coupled to mass spectrometry. Following, pyrolyzed materials obtained between 500–1000◦ C were characterized by XRD, Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Above 600◦ C, Raman spectra of all samples showed the presence of graphitic carbon, which plays a role in the degree of crystallinity of produced inorganic phases (for comparison purposes, M2 Al-CO3 materials were investigated after calcination in the same experimental conditions). XRD patterns of Mg2 Al-CMC pyrolyzed between 600–1000◦ C showed poorly crystallized MgO and absence of spinel reflections, whereas for Zn2 Al-CMC, it was observed well crystallized nanometric ZnO at 800◦ C, and ZnAl2 O4 and γ-Al2 O3 phases at 1000◦ C. Above 800◦ C, the carbothermic reaction was noticed, transforming ZnO to zinc vapour. This study opens perspectives for nanocomposites preparation based on carbon and inorganic (mixed) oxides through precursors having organic-inorganic interactions at the nanoscale domain.