Separation and preconcentration of Cd(II) ions from environmental samples by solid phase extraction using brewed manufactured black tea wastes

In the present study, the usability of brewed tea waste (DÇA) as an adsorbent was investigated for the first time in the literature in order to separate and preconcentrate Cd(II) ions from various food and water samples by solid phase extraction (SPE) method before their determination by flame atomic absorption spectrophotometer (FAAS). DÇA was characterized by FTIR, Boehm titration and pHpzc. SPE experiments were carried out with a batch system, and 5.0 mL of 0.5 M HNO3 solution was used for the desorption of Cd(II) ions. Basic experimental variables such as solution pH, DÇA amount, eluent type and concentration, adsorption and desorption equilibrium time, and sample volume were optimized for the quantitative recovery of Cd(II) ions. The detection limit, relative standard deviation and preconcentration factor for Cd(II) ions were calculated as 0.56 µg L-1, 3.03% and 100, respectively. The Langmuir isotherm model was found to be suitable for the adsorption of Cd(II) ions on the DÇA, indicating that the active adsorption sites on the DÇA surface are homogeneously distributed. The maximum adsorption capacity of DÇA was calculated as 41.5 mg g-1 using the Langmuir isotherm model. A second-order kinetic model was found to be appropriate to describe the adsorption kinetics of Cd(II) ions on DÇA. After testing the accuracy of the method with spike/recovery studies, the method was successfully applied to water samples (creek and sea water) and food samples (eggplant, lettuce, parsley, apple and apricot) for the determination of their Cd(II) concentrations.