Determination of Six Heavy Metal Elements in High Chloride and High Salt Wastewater by Solid Phase Extraction with Chelex 100 Resin-ICP-AES

The target elements in high chloride and high salt wastewater as Cu, Pb, Zn, Ni, Cd and Mn were extracted with Chelex 100 resin in the optimized solid phase extraction (SPE) conditions with ICP-MS, and determined by ICP-AES. The samples of high chloride and high salt wastewater were digested by nitric acid and the solution was made up with acetate buffer solution (pH 6.5). The solid phase extraction column pre-filled with Chelex resin was activated with 0.5 mol·L^-1 ammonium acetate solution, and after adding 10 mL of the sample solution at a rate of 1 mL·min^-1, the column was rinsed with 0.5 mol·L^-1 ammonium acetate solution and water. 5% (volume fraction) nitric acid solution was used for elution of the column at a rate of 1 mL·min^-1, and 10 mL of eluate was collected and analyzed for determination of the content of Cd, Mn, Ni, Zn, Cu and Pb at detection wavelengths of 214.439, 257.610, 231.604, 206.200, 327.395, 220.353 nm. The results showed that linearity ranges of standard curves of the target elements were in the range of 0.1-10.0 mg·L^-1, with detection limits ranged from 4.0×10^-4mg·L^-1 to 3.0×10^-2mg·L^-1. The spiked recovery tests were made on the 3 wastewater samples (containing NaCl, NH₄Cl and NaCl-NH₄Cl, respectively), and mass concentrations of the target elements were all less than 1.600 mg·L^-1, giving recoveries in the range of 92.2%-102%, and RSDs (n=9) of the determined values in the range of 0.50%-3.5%.