Raw, activated and modified biosorbents for the speciation of C. I. acid red 2 from aqueous solutions: An adsorption study

Abstract

Adsorptive removal of C. I. Acid Red 2 dye in the aqueous solution has been carried out on the various surfaces. This study describes the comparative adsorption of dye using mustard cakes (MC), sugarcane bagasse ash (SBA) and leaves of water hyacinth (WH) in different forms. The effects of initial adsorbate concentration, contact time, adsorbent dosage, temperature and pH of the medium on the adsorption of C. I. Acid Red 2 (C.I.A.R-2) or Methyl Red (MR) were investigated. The biosorbents were characterized by using modern technique (FTIR, SEM, and XRD). The maximum adsorption capacity of MR occurred at pH 2 and 4 for different adsorbent materials. Adsorption of the dyes was found to increase as the adsorbent dosage increases but decreases as initial concentration of the adsorbate (dye) increases. This is due to the fact that the active site of the adsorbent can adsorb a certain concentration of the dye. The C. I. Acid Red 2 adsorption kinetics was analyzed by using pseudo-first order and pseudo-second order kinetic models. The results indicated that the adsorption of C. I. Acid Red 2 (C-Colour, I -Index) onto various surfaces is best described using a pseudo-second order kinetic model. The Langmuir, Freundlich and Temkin adsorption isotherms were also studied and the data are well fitted with Freundlich isotherm. On the basis of the results it was demonstrated that mustard oil cake, sugarcane bagasse ash and leaves of water hyacinth are promising adsorbent materials which can be used to clean up textile dyes from wastewater. Key words: C.I.A.R-2, sugarcane bagasse ash (SBA), mustard cakes (MC) and water hyacinth (WH), adsorption.