The capability of rice bran for removal of Nylomine Red (Acid Red 138) an anionic monoazo direct dye, from aqueous solutions was studied. The effect of various experimental parameters such as treatment of the bran, particle size, contact time, stirring speed, temperature and pH of solutions were studied, and the optimal conditions were selected. The dye sorption onto rice bran increased in the presence of inorganic salt. It was found that the rice bran with a mesh of 20 and activated with saturated sodium chloride have higher adsorption capacity. The optimum reaction time, at a speed of 30 rpm, is 60 min. At initial pH of 2 and at room temperature, AR 138 was removed more effectively. The isothermal data for biosorption followed the Langmuir and Freundlich models.
Key words: Acid dye, rice bran, adsorption.
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