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