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1.
Carbohydr Polym ; 118: 165-9, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25542122

RESUMO

The study reports on the preparation of cellulose nanocrystals (CNCs) from wastepaper, as an environmental friendly approach of source material, which can be a high availability and low-cost precursor for cellulose nanomaterial processing. Alkali and bleaching treatments were employed for the extraction of cellulose particles followed by controlled-conditions of acid hydrolysis for the isolation of CNCs. Attenuated total reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy was used to analyze the cellulose particles extracted while Transmission electron microscopy images confirmed the presence of CNCs. The diameters of CNCs are in the range of 3-10nm with a length of 100-300nm while a crystallinity index of 75.9% was determined from X-ray diffraction analysis. The synthesis of this high aspect ratio of CNCs paves the way toward alternative reuse of wastepaper in the production of CNCs.


Assuntos
Celulose/química , Nanopartículas/química , Nanoestruturas/química , Papel , Conservação dos Recursos Naturais , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Waste Manag ; 26(10): 1173-9, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16274981

RESUMO

White rice husk ash (RHA), an agriculture waste containing crystalline tridymite and alpha-cristobalite, was used as a silica source for zeolite Beta synthesis. The crystallization of zeolite Beta from RHA at 150 degrees C in the presence of tetraethylammonium hydroxide was monitored by XRD, FTIR and (29)Si MAS NMR techniques. It was found that zeolite Beta started to form after 12h and the complete crystallization of zeolite Beta phase was achieved after 2d. XRD, (29)Si MAS NMR and solid yield studies indicate that the transformation mechanism of silica present in RHA to zeolite Beta involves dissolution of the ash, formation of an amorphous aluminosilicate after 6h of crystallization, followed by dissolution in the mother liquor and final transformation to pure zeolite Beta crystals.


Assuntos
Cristalização/métodos , Oryza/química , Sementes/química , Dióxido de Silício/química , Resíduos/análise , Zeolitas/química , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Tetraetilamônio , Difração de Raios X
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