Grapefruit peelings as a promising biosorbent for the removal of leather dyes and hexavalent chromium

• Autor(a) principal: Rosales, E.
• Data de Publicação: 2016
• Outros Autores: Meijide, J., Tavares, T., Pazos, M., Sanromán, M. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/1822/41901
• topic: Grapefruit peelings; Adsorption; Tannery effluent; H2O2; Pretreatment; H O 2 2; Science & Technology

The objective of this study was to find a suitable and versatile agroforestry waste as alternative low-cost biosorbents for the removal of inorganic and organic compounds present in the wastewater of tannery industry [leather dyes and Cr(VI)]. Grapefruit peelings, fern, eucalyptus barks, oak leaves and cane pruning of grapevines were evaluated as biosorbents. Among them, grapefruit peelings showed the best results reaching 45 and 55% for the mixture of dyes and Cr(VI), respectively. A significant improvement in the performance of this biosorbent was obtained when it was pretreated with H2O2 (1M) attaining the highest removal capacity of 80% and 100%, respectively. This biosorbent was characterised showing an adsorption capacity of 1.1003meq/g and pHZPC 3.48. The adsorption working parameters, kinetics and isotherms were deeply studied in order to scale up the process to a continuous treatment system. Adsorption isotherms data fitted well to the Langmuir model with a maximum uptake of 37.427mg/g for dyes mixture and 39.0628mg/g for Cr(VI). Finally, the dynamic behaviour of the system, operating at different flow rates, was evaluated using a Homogeneous Surface Diffusion Model. Pretreated grapefruit peelings demonstrated to be a suitable low-cost biosorbent in the treatment of wastewater of tannery industry.