Despolimerización de Lignina Extraída de Carbón de Bajo Rango por el Método de Radiación UV/TiO2 y su Uso en la Elaboración de Madera Artificial

Abstract

On this research, lignin depolymerization by ultraviolet radiation and catalyzed by titanium dioxide was studied and later it was used as a copolymer in making agglomerated boards with rice husks. Lignin was extracted from a low range charcoal sample coming from Paipa-Boyacá using Sosa Method. Depolymerization on samples of 100 ml 50 mg/L lignin for 0, 2, 6, 10 hours and catalyst amounts in ratios 1:1; 1: 3.3; 1: 6.6; 1:10 lignin and TiO2 respectively were standardized by irradiation with 45W UV light. Results allowed to select optimal values of 6 hours of irradiation and the catalyst in proportion of 1 lignin by 3.3 of TiO2 for depolymerization. It produced a 22% degradation on lignin. Later, depolymerized lignin was activated by the hydroxymethylation reaction with formaldehyde. For boards preparation components were mixed in proportions of 60% rice husk, 7.4% lignin, 14.9% melamine and 17.7% formaldehyde. Mixture was heated to 100 ° C for one hour in molds. Three boards were produced with the above-mentioned proportions and with following characteristics: board 1 was made with unmilled rice husk and Kraft lignin (Sigma-Aldrich); board 2 was made with milled rice husk and Kraft lignin and board 3 was made with milled rice husk and activated lignin. All boards were subjected to mechanical tests of bending, compression, traction and water absorption. Board 2 showed the most suitable results according to ASTM D 143 norm.