Laboratory for Leather and Environmental Studies (LACOURO), Chemical Engineering Post-Graduated Program (PPGEQ), Federal University of Rio Grande do Sul (UFRGS), Av. Luiz Englert s/n°, Porto Alegre, RS, 90040-040, Brazil. [Email]
The removal of toxic compounds (azo dyes) from dyeing wastewater was investigated by an environmentally friendly activated carbon produced from solid waste generated in the tannery process, the cattle hair (CHW), activated with H3PO4 (AC-CHW), suggesting a life cycle extension for this material from leather processing. Preliminary tests with aqueous solutions containing Acid Brown 414 (AB-414) and Acid Orange 142 (AO-142) removed 71.06% and 73.05%, respectively. The activated carbon was characterized by zeta potential (ZP), functional groups (FTIR), elemental composition, sorbent specific surface area, and pore size distribution (BET/BJH). The specific surface area showed low values when compared to commercial activated carbon, but average pore diameter was higher, which facilitates the adsorption of larger and complex molecules, such as those present in real wastewaters. Through SEM and FTIR, the presence of the toxic compounds studied in the AC-CHW after sorption process was observed, where the results indicated that the functional groups of -CH=CH- participated in the removal process for these compounds. The removal efficiency obtained with AC-CHW was 51.94% and 49.73% for the dyeing wastewater containing AB-414 and AO-142, respectively. The obtained results open a promising via to use AC-CHW as efficient eco-friendly sorbent for the treatment of leather wastewater.