Sulfur-modified Chitosan Hydrogel as an Adsorbent for Removal of Hg(II) from Effluents

Sulfur-modified chitosan hydrogel (SMCH) was successfully synthesized by grafting dimethyl 3,3'-dithiodipropionate onto chitosan and then crosslinking with N,N1-methylend diacrylamide (MBA). The structure and properties of chitosan and sulfur-modified chitosan (SMC) were characterized and analyzed by Fourier transform infrared spectroscopy (FT-IR), Nuclear magnetic resonance (H-1 NMR), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). Meanwhile, chitosan hydrogel and SMCH were characterized by Scanning electron microscope (SEM). In addition, static adsorption Hg(II) ions properties of chitosan hydrogel and SMCH were also investigated. The FT-IR. and H-1 NMR manifested that SMC was synthesized successfully. The XRD and TGA showed that the crystallinity and thermal stability of SMC decreased. SEM showed that the SMCH had much more pores and bigger specific surface area than chitosan hydrogel. The result of adsorption experiment indicated that the SMCH showed noticeable improvements in the adsorption capacity of Hg(II), and had the highest adsorption capacity (187.5 mg/g) at pH 5.0. The equilibrium was achieved at 40 min. And the maximum adsorption capacities were 186.9 mg/g of SMCH.