Conversion of agricultural residues into activated carbons for water purification: Application to arsenate removal

Abstract

The conversion of two agricultural wastes, sugar beet pulp and peanut hulls, into sustainable activated carbons is presented and their potential application for the treatment of arsenate solution is investigated. A direct and physical activation is selected as well as a simple chemical treatment of the adsorbents. The material properties, such as BET surface areas, porous volumes, elemental analysis, ash contents and pH_PZC, of these alternative carbonaceous porous materials are determined and compared with a commercial granular activated carbon. An adsorption study based on experimental kinetic and equilibrium data is conducted in a batch reactor and completed by the use of different models (intraparticle diffusion, pseudo–second-order, Langmuir and Freundlich) and by isotherms carried out in natural waters. It is thus demonstrated that sugar beet pulp and peanut hulls are good precursors to obtain activated carbons for arsenate removal.

Keywords:

• Activated carbon
• adsorption
• arsenate
• iron impregnation
• residue valorization
• water treatment

Acknowledgments

We acknowledge financial support from the Consejo Nacional de Ciencia y Tecnología de México (CONACYT) by a scholarship grant for JTP.