Investigation of preconcentration conditions of cadmium ions using modified walnut shells from aqueous solutions

Juglans regia L. shells as agricultural wastes can be considered as alternative sorbents to minimize the problems associated with heavy metal pollution. In this study Juglans regia L. shells and Juglans regia L. shells modified with hydrazine hydrate were used as sorbents and compared for the preconcentration of Cd(II) ions from aqueous solution. For the characterization of sorbents, the scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis and fourier transform infrared spectroscopy (FTIR) were used. Preconcentration studies were performed with column method and pH, eluent type and concentration, flow rate, sample volume and interfering ions effect were studied to determine the optimum column parameters. The limit of detection (LOD) of the sorbents are 0.31 µg L-1 and 0.18 µg L-1, respectively. According to the Langmuir isotherm model for both sorbents KL=0.030 L mg-1, R2=0.994, 0.016 L mg-1, R2=0.991 and maximum adsorption capacities of the sorbents were found to be as 29.6 mg g-1 and 65.7 mg g-1, respectively. The proposed method was successfully applied to the certificated reference material (SRM-NIST 1640) analysis and satisfactory results were obtained.