Application of Peppermint Plant Residues for Ions of Copper and Zinc Removal from Aqueous Solutions

Residues mint were used to remove two heavy metal ions, copper and zinc. The adsorbent was washed with nitric acid, hydrochloric acid, sulfuric acid and was reached to neutral pH using distilled water. The adsorbed ions were desorbed from biosorbent with 0.1 M Na2S2O3 and then was measured by flame atomic absorption spectrometry. The effective parameters such as pH, type and volume of eluent, and sorption capacity were investigated. The calibration curve was linear in the range of 0.010-5.0 µg mL-1 Cu and 0.080-2.0 µg mL-1 Zn. Detection limits for Cu (II) and Zn (II) ions were 4.8 × 10-3 and 2.6 × 10-3 µg mL-1, respectively. Seven replicate determinations of a mixture containing 0.5 µg mL-1 each of the elements gave a relative standard deviation of ±1.20% and ±1.17 %, respectively. To describe the mechanism of copper and zinc ions biosorption, the Langmuir and freundlich isotherm models were tested on the equilibrium data. The maximum adsorption capacity of Cu and Zn on the adsorbent were 16.48 and 12.85 mg g-1and the preconcentration factors were 150 and 100, respectively.