Characterization and use of biosorbents prepared from forestry waste and their washed extracts to reduce/remove chromium

This study aimed to characterize forestry waste of araucaria, eucalyptus and pine and their aqueous extracts to evaluate their performance in the reduction/removal biosorption of chromium. The biosorbents present a complex and rich composition of both organic and inorganic solubilizable compounds. These results confirmed the need of biomass pretreatment for its adequate use as biosorbent. The extracts obtained in the washing cycles at different pHs presented high organic loads. The pine is distinguished as the best biosorbent, and its performance is increased by prior washing in natural medium. Eucalyptus extract produces fastest Cr(VI) reduction due to the presence of high concentration of dissolved organic matter. The washing process of the biosorbents, besides improving the efficiency of overall chromium biosorption, prevents mobilization of the solubilizable compounds in the treated effluent. The biosorbents tested have potential for application in the treatment of wastewater containing chromium, at least in similar levels to those studied.