Bioadsorbtion of industrial dyes from aqueous solution onto water hyacinth (Eichornia crassipes): Equilibrium, kinetic, and sorption mechanism study

In the present investigation, bioadsorbtion of different industrial dyes, such as, methylene blue, Congo red, crystal violet, and malachite green from aqueous solution have been performed by water hyacinth using lab-scale batch bioreactor. Maximum removal of different dyes, such as, methylene blue, Congo red, crystal violet, and malachite green were found at pH 7.0, 6.0, 8.0, and 8.0, respectively. Optimum doses of adsorbent were found to be 6.5, 7.5, 6.0, and 7.0 g L-1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum initial dyes concentration were found to be 65, 75, 70, and 75 mg L-1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum contact time for adsorbtion was found to be 5 days for all the dyes. The maximum percentages of removals were found to be 90, 88, 92, and 90% for methylene blue, Congo red, crystal violet, and malachite green, respectively. The adsorption kinetic data are adequately fitted to the pseudo-second-order adsorption kinetic model. The Langmuir isotherm model well described the equilibrium dyes uptake. High value of intra particle diffusion parameter (Ki), and diffusion coefficient (Di) suggest that water hyacinth is an effective adsorbent for the removal of industrial dyes from wastewater. © 2013 © 2013 Balaban Desalination Publications. All rights reserved.