Post on 22-Nov-2015
J. Chem. Chem. Eng. 6 (2012) 124-137
P U B L I S H I N G
Increase of Lignin Reactivity by Means of
Depolymerization and Hydroxymethylation for Its Use in
Synthetic Wood Elaboration
Alvaro Jimnez. Marco Vega and Bibiana Gordillo
Department of Chemistry, Science and Education Faculty, University Distrital Francisco Jos of Caldas, Bogot 111931, Colombia
Received: November 01. 2011 / Accepted: November 30. 2011 / Published: February 25. 2012.
Abstract: Lignin was extracted from peat by Sosa Method. In orderto increase its chemical activity. it is necessary to make a structural moditlcation by hydroxymethylation so it can be used in preparation of synthetic wood. Depolymerization was made by two methods: (1) reaction of lignin with NaGTI 2%; (2) exposition of lignin to U V beam for 6, 12. 24, 36. 48 and 60 hours. The best depolimerization result was with exposition of lignin to UV by 12 hours since phenylpropanoic structure with higher number of free positions (unoccupied carbons) in C3 and C5 of its aromatic ring was obtained. It is known by Mannich Reaction and determination of phenolic OH by UV analysis. Later, its reactivity was increased by hydroxymethylation process by means of reaction of depolymerizated product with formaldehyde and later with glyoxal since it is less toxic. The modified product was mixed with six different kinds of resins (phenol-formaldehyde. urea-formaldehyde. melamine-formaldehyde, Glyoxal-formaldehyde. urea-formaldehyde and melamine-formaldehyde) to obtain a better mechanical characteristic as a synthetic wood. The best result was the one with melamine-formaldehyde. Finally. this product was mixed with testa rice so final product showed a great hardness and a shinny and smooth appearance.
Key words: Depolymerization, hydroxymethylation. lignin. peat.
1. Introduction
Deforestation does not help in any way the
environment recuperation. Deforestation helps
increasing the greenhouse effect. Politics that have
been reducing deforestation in last ten years are not
enough, so it is necessary to crate new ways that avoid
process of deforestation.
If deforestation rate contines as today is, Colombia
won't have any forest in 100 years. Research groups
have been looking for different alternatives that help to
elimnate this world problem. Since lignin is a main
constituent of wood, some of them have proposed the
use of lignin as a raw material in order to produce
synthetic wood.
Actually, lignin is obtained from paper industry so
'Corresponding author: Bibiana Gordillo, Bachelor, research field: coal industry. E-mail: bibisOO'msn.com.
deforestation problem is continuous. Since five years
ago, Coal Research Group from "University
Francisco Jos of Caldas of Bogot" has been
working with lignin extracted from coal. Colombia
has many tons of coal stockpiles. Lignin is a
tridimensional biopolymer with high molecular
weight that is produced by the link of different acids
and alcohols such as phenylpropilic alcohol,
cumarilic, etc.. Lignin gives stiffness, hardness and
flexibility to wood. Lignin doesn't have the same
structure, because it depends on the wood which it
comes from (Fig. 1) [ 1 ] .
In this way, it is very important for the Research
Group to investgate lignin extraction process from low
rank coals since it comes from vegetal tissues.
Extracted lignin has been used in elaboration of
synthetic producs that can replace natural wood in
Modificacin estructural de la lignina extrada a partir de carbones de bajo rango para la obtencin de madera sinttica
Structural modification of extracted lignin from low rank coals for manufacturaron of synthetic woods
JESS ALVARO JIMNEZ MONTOYA
Qumico, Licenciado en Qumica, Magster en Qumica. Profesor Titular de la Universidad Distrital Francisco Jos de Caldas. Bogot, Colombia.jajymenez@gmail.com
BIBIANA GORDILLO DAZ
Estudiante de Licenciatura en Qumica de la Universidad Distrital Francisco Jos de Caldas. Bogot, Colombia. bibisOO@msn.com
MARCO ANTONIO V E G A ATUESTA
Estudiante de Licenciatura en Qumica de la Universidad Distrital Francisco Jos de Caldas. Bogot, Colombia, vegatul82@yahoo.com
Clasificador, del articulo: investigacin (Conciencias)
Fecha oe receDcin: mayo 7 de 2010 Fecha de aceptacin: noviembre 23 de 2010
Palabras clave: Aglomerante, Carbn, Lignina, Madera sinttica, Turba.
Key words: Binder, Coal, Lignine, Synthetic wood, Peat.
R E S U M E N
El grupo Investigacin en Carbones de la Universi-dad Distrital Francisco Jos de Caldas ha trabajado en la extraccin de lignina a partir de carbn de bajo rango y de turba, con el fin de emplearla en la elaboracin de madera sinttica y de esta manera aplicarla a la industria maderera.
En una primera parte se aplicaron los mtodos Sosa, Sulfato y Bisulfito [ 1 ] , modificados para la extrac-cin de lignina a partir de pino y cedro, se evidenci que el mtodo Sosa era el de mayor rendimiento. Este mtodo fue aplicado para la extraccin de lig-
nina a partir de una muestra de carbn leonardtico. Posteriormente, sta se utiliz en la elaboracin de la resina lignina-fenol-formaldehido, la cual acta como aglomerante de fibras naturales [2].
La segunda parte se fundament en la estandarizacin del mtodo Sosa [3], en el cual se modific la presin utilizando autoclave para una muestra de turba, lo cual mejor el rendimiento. La lignina obtenida se emple en la elaboracin de resinas tales como lignina-fenol-formaldehdo, lignina-resorcinol-formaldehdo y lignina-polipropileno, las cuales fueron utilizadas empleando como fibra natural bagazo de caa.
68 Revista Tecnura \n 15 j Numero 28 \s 68 - 82 j Enero - Junio de 2011