Introduction: In recent years, use of bio char as bio sorbent for pollution control of aqueous solutions containing heavy metals, has been considered by researchers. In the present study, the efficiency of wheat straw bio char and corn straw bio char for the removal of
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Introduction: In recent years, use of bio char as bio sorbent for pollution control of aqueous solutions containing heavy metals, has been considered by researchers. In the present study, the efficiency of wheat straw bio char and corn straw bio char for the removal of Zinc from aqueous solutions had been investigated under the influence of various factors such as pH, contact time, adsorbent dose and adsorbent concentration.
Material and Methods: Langmuir and Freundlich models were used to describe the adsorption isotherm and Pseudo-first order and pseudo-second order kinetic models were applied for description of adsorption kinetics.
Results: The optimum pH for Zn adsorption was found to be 5 by two bio chars. With increasing contact time, Zn adsorption efficiency was increased by two adsorbents and at 24 hours reached to equilibrium. The increase of bio char dosage until 20 g.L-1, the percentage of Zn removal in solutions was enhanced by tow adsorbents; however, the upper dosage of adsorbent caused a decrease in removal efficiency. The results indicate that the Langmuir model better fits on adsorption data than Freundlich model. Accordingly, Zn adsorption capacity by corn straw bio char (9.60 mg. g-1) was higher than the wheat straw bio char (6.77 mg.g-1). The kinetic data were better represented by the pseudo-second-order than the pseudo-first-order kinetic model, so it seems that the dominant process of Zn adsorption to be a chemisorption.
Conclusion: The results showed that the bio chars which used in this experiment can be applied as a low-cost, effective and available adsorbent for removal of Zn from aqueous solutions.
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