Abstract The current study describes the removal of methylene blue (MB) and crystal violet (CV) dyes from aqueous media using carnauba straw as a bioadsorbent. Batch adsorption experiments were carried out at different conditions of pH (1.0 – 10.0), temperature (25 – 55 °C), time (5 – 360 min) and adsorbate concentration (0.1 – 2.0 mmol L-1). The adsorbent was characterized by thermogravimetry, X-ray diffraction, FTIR, pHpzc and conveniently compared with other lignocellulosic materials. Langmuir, Freundlich and Sips adsorption isotherms were applied and the results showed that the Sips and Langmuir models described better the experimental data regarding both dyes. The maximum adsorbed amounts were 0.294 mmol g-1 for MB (25 °C) and 0.399 mmol g-1 for CV (55 °C). The effect of temperature on the equilibrium adsorption was investigated, indicating different patterns for MB (exothermic) and CV (endothermic).
Keywords lignocellulosic, dye removal, carnauba, bioadsorbent.