Obtaining the conditions of nitration of lignin for the optimization of the adsorption of Ni and V

Published in: Innovation in Engineering, Technology and Education for Competitiveness and Prosperity: Proceedings of the 11th Latin American and Caribbean Conference for Engineering and Technology
Date of Conference: August 14-16, 2013
Location of Conference: Cancun, Mexico
Authors: Narciso Pérez
Jean González
Alejandra Meza
Johliny del Carmen Casanova Parra
Refereed Paper: #280

Abstract:

In English:
The adsorption process of Ni and V with lignin as adsorbent in acid solution is of chemical type (chemisorption), so an increase in the groups that function as active sites for adsorption on lignin should increase the adsorptive capacity of the same. A modification of the lignin was raised, by means of adding nitro groups and using the nitric acid (HNO 3 ) as nitration agent in sulfuric acid, and then was evaluated its effect on the adsorption of Ni and V. For this, an experimental design of type 2 4 was used, in which four operational variables were studied. These variables were selected as those that during the nitration could affect the amount of active sites, such as nitric acid concentration, temperature, time and stirring rate of nitration. From this experimental work were obtained lignins with high adsorption capacity for both metals. A statistical analysis showed that between the four operational variables studied, only concentration of HNO 3 and the temperature of nitration, generate significant changes for adsorption, its for this that it is recommended working at the highest possible conditions for these two variables and the lowest possible for the rest.


In Spanish:
El proceso de adsorción de Ni y V con lignina como agente adsorbente en solución ácida es de tipo químico (quimisorción), por lo que un aumento en los grupos que funcionan como centros activos para la adsorción en la lignina debe aumentar la capacidad adsortiva de la misma. Se planteó modificar la lignina mediante la incorporación de grupos nitro usando como agente de nitración ácido nítrico HNO 3 en ácido sulfúrico y posteriormente se evaluó su efecto en la adsorción de Ni y V. Para ello se realizó un diseño experimental del tipo 2 4 , donde se estudiaron cuatro variables operacionales que durante la nitración podrían afectar la cantidad de centros activos, tales como: concentración de ácido nítrico, temperatura, tiempo y velocidad de agitación de la nitración, del trabajo experimental se obtuvieron ligninas con alta capacidad de adsorción de ambos metales. A partir de un análisis estadístico se encontró que de las cuatro variables operacionales estudiadas sólo la concentración del HNO 3 y la temperatura de nitración generaban cambios significativos en la adsorción, por lo que se recomienda trabajar a las condiciones más altas posibles para esas dos variables y las más bajas posibles para el resto.