Synthesis and characterization of a surface-grafted Pb(ii)-imprinted polymer based on activated carbon for selective separation and pre-concentration of Pb(ii) ions from environmental water samples

Abstract

Even the lowest concentration level of lead (Pb) in the human body is dangerous to health due to its bioaccumulation and high toxicity. Therefore, it is very important to develop selective and fast adsorption methods for the removal of Pb(II) from various samples. In this paper, a new Pb(II) ion-imprinted polymer (Pb(II)-IIP) was prepared with surface imprinting technology by using lead nitrate as a template, for the solid-phase extraction of trace Pb(II) ions in environmental water samples. The imprinted polymer was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and N₂ adsorption–desorption isotherms. The separation/pre-concentration conditions for Pb(II) were investigated, including the effects of pH, shaking time, sample flow rate, elution conditions and interfering ions. Compared with non-imprinted particles, the ion-imprinted polymer had a higher selectivity and adsorption capacity for Pb(II). The pseudo-second-order kinetics model and Langmuir isotherm model fitted well with the adsorption data. The relative selectivity factor values (α_r) of Pb(II)/Zn(II), Pb(II)/Ni(II), Pb(II)/Co(II) and Pb(II)/Cu(II) were 168.20, 192.71, 126.13 and 229.39, respectively, which were all much greater than 1. The prepared Pb(II)-imprinted polymer was shown to be promising for the separation/pre-concentration of trace Pb(II) from natural water samples. The adsorption and desorption mechanisms were also proposed.