Adsorptive removal of chromium from aqueous solutions using flax (Linum usitatissimum): Kinetics and equilibrium studies

Abstract

Chromium (Cr) ions, discharging from different industrial activities, especially from leather tanning industries, are becoming a major threat for the environment and human health. Therefore, elimination of chromium ions from industrial effluents should be addressed with great attention. Hence, this study was conducted for evaluating the possibilities of using an agricultural waste “flax” to eliminate Cr (III) ions from aqueous solutions. In order to assess the effects of various experimental parameters (i.e., contact time, pH, adsorbent amount, initial chromium ion concentration and particle size) on Cr (III) ions adsorption process, the batch adsorption study was conducted. This study revealed that adsorption of Cr (III) ions by flax required 420 min to reach equilibrium. On the other hand, the maximum (~70%) Cr (III) ions removal was observed at pH value of 2.0. The desorption efficiency with 0.5 M KOH was found to be 90%. The Langmuir and Freundlich isotherms models were in better correlation with experimental data, according to equilibrium studies. Kinetic experiments showed that the first order kinetics with a rate constant of 0.01 min−1. Use of real wastewater sample became a great success for removing of Cr (III). This result suggests that the flax plant has the potentiality to become an effective and environmentally friendly economical adsorbent for the removal of Cr (III) ions significantly from waste water.