Application of molybdenum disulfide nanosheets adsorbent for simultaneous preconcentration and determination of Cd(II), Pb(II), Zn(II) and Ni(II) in water samples

In this research, the two-dimensional molybdenum disulfide nanosheets (MoS2-NSH) were synthesized and successfully used as an effective adsorbent for preconcentration of trace amounts of four heavy metal ions (including, Cd, Ni, Zn and Pb) before measurements with flame atomic absorption spectrometry (FAAS). The prepared MoS2-NSH was characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDS) and transmission electron microscopy (TEM). The main analytical parameters which can influence the quantitative recoveries of target analyte ions; such as solution pH, eluent type and its volume, adsorbent dosage and initial sample volume, were investigated. Under the optimized conditions, the recoveries of metal ions were > 90% at pH of 5.5, and the limits of detection values were found to be 0.37, 0.97, 0.76 and 1.09 μg L−1 for Cd(II), Ni(II), Zn(II) and Pb(II), respectively. The relative standard deviations (% RSD) for target ions were less than 5.3%. In addition, based on the experimental data, the kinetics studies and adsorption isotherms were evaluated and the results showed that the pseudo-second-order kinetic model and Langmuir adsorption isotherm were well-fitted with the ions adsorption data. The suggested procedure has been successfully utilized in the analysis of some environmental water samples with satisfactory recoveries in the range of 93.6 to 107.2%.