LAUSR

BACKGROUND Juglans regia L. shells as agricultural wastes can be considered as alternative sorbents to minimize the problems associated with heavy metal pollution. OBJECTIVE 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. METHODS 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. For preconcentration, solid phase extraction (SPE) technique was used. Preconcentration studies were performed with column method and pH, eluent type and concentration, sample volume, flow rate and interfering ions effect were studied to determine the optimum column parameters. RESULTS The limit of detection (LOD) of the sorbents are 0.31 µg/L and 0.18 µg/L, respectively. According to the Langmuir isotherm model for both sorbents KL=0.030 L/mg, R2=0.994, 0.016 L/mg, R2=0.991 and maximum adsorption capacities of the sorbents were found to be as 29.6 mg/g and 65.7 mg/g, respectively. The mean recoveries and RSD values at 95% confidence level (N = 6) for Cd(II) were 100.9% and 3.42; 100.6% and 3.79 for the JRS and JRS-HH sorbents, respectively. CONCLUSIONS In this method good results obtained when compared with the literature and the proposed method was successfully applied to the certificated reference material (NIST 1640) analysis. Highlights: Juglans Regia L. shells are an effective and inexpensive sorbent for preconcentration metal ions when modified. Thus, low-cost agricultural wastes are both recovered and have an economic value.