Evaluation of Barberry Stems ash on Chromium (VI) Removal Efficiency from Aqueous Solutions

Chromium occurs mainly in the oxidation states (III) and (VI), and finds in the wastewater industries such as electroplating, glass, ceramic, leather and tanning, tannery industries. Hexavalent Chromium (VI) is reported as confirmed carcinogen. The aim of this study was to evaluate removal efficiency of chromium (VI) by using Barberry stems powder from aqueous solutions.
This study was done in laboratory scale. The Barberry stems powder prepared in lab conditions and Pulverized using ASTM standard sieves (40-60 mesh). The effects of adsorbent dose (Barberry stems powder), initial concentration of hexavalent chromium, contact time and pH on the removal chromium were investigated. The concentration of chromium (VI) in all samples measured by spectrophotometer at 540 nm. For better understanding of the adsorption process, the experimental data were analyzed with Langmuir and Freundlich isotherm models and pseudo first order and pseudo second order kinetic studies. Finally, the data were analyzed by EXCEL.
The results showed that the removal efficiency of Cr was fixed and 100% in all amounts of adsorbent. By increasing of reaction time, the Cr removal rate increased and by increasing of Cr initial concentration and pH, the removal efficiency decreased. By increasing of pH from 2 to 9, the Cr removal efficiency with 2 mg/L chromium decreased from 100% to 16.4%. Furthermore, the data were well fitted with Langmuir isotherm and pseudo- second -order kinetic.
According to the results, Barberry stems powder is able to absorb the Cr (VI). Removal efficiency of Cr (VI) in pH=2 was at its optimum capacity. The results of this study demonstrated that the Barberry stems powder can be used as an effective and appropriate adsorbent.