Study on the polypeptide-functionalized magnetic chitosan microspheres that specifically adsorb Hg (II) ions

Here, we present an effective and environmentally friendly approach for fabricating polypeptide functionalized magnetic chitosan microspheres (Fe3O4@CTS@PS) based on the effective binding of polypeptide (GCTCWCSGE) with mercury ions (Hg (II)). The morphology and component of the prepared Fe3O4@CTS@PS was characterized via scanning electronic microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer. Effects of the polypeptide sequence, pH, adsorption time, initial concentration, temperature on the adsorption performance and anti-interference ability and reusability were studied. The Fe3O4@CTS@PS had excellent adsorption selectivity for Hg (II) and the adsorption capacity can reach to 218.8 mg·g−1 at 318 K and pH5.0. Kinetic data was correlated well with the pseudo-second-order model and adsorption isotherm agreed well with the Langmuir isotherm model. The reusability of Fe3O4@CTS@PS was also investigated and the adsorption capacity of Fe3O4@CTS@PS for Hg(II) still remained 92% of the initial values after four adsorption-elution cycles (eluting agent was Na2S2O3). The prepared Fe3O4@CTS@PS showed excellent adsorption performance for Hg (II) in real samples (lake water, milk and nori) and was a promising adsorbent in practical applications.