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Keywords:

  • Biosorption;
  • Equilibrium uptake capacity;
  • Langmuir isotherm;
  • Nymphaea rubra

Abstract

In the present work, biosorption of Cr(VI) by Nymphaea rubra was investigated in batch studies. Batch experiments were conducted to study the effect of initial sorbent dosage, solution pH and initial Cr(VI) concentration. The results showed that the equilibrium uptake capacity was increased with decrease in biomass dosage. The Cr(VI) removal was influenced by the initial chromium compound concentration. Langmuir and Freundlich adsorption isotherm models were used to represent the equilibrium data. The Freundlich isotherm model was fitted very well with the equilibrium data when compared to Langmuir isotherm model. The sorption results were analyzed for pseudo-first order and pseudo-second order kinetic model. It was observed that the kinetic data fitted very well with the pseudo-second order rate equation when compared to the pseudo-first order rate equation. Fourier transform infrared spectrum showed the presence of different functional groups in the biomass. The surface morphology of the sorbent was exemplified by SEM analysis. Aquatic weeds seem to be a promising biosorbent for the removal of chromium ions from water environment. This paper reports the research findings of a laboratory-based study on the removal of Cr(VI) from the synthetic solution using the dried stem of N. rubra as a biosorbent.