CS-EGDE/Fe 3 O 4 凝胶微球对水中重金属离子的吸附性能及机理研究
摘要
The natural biomass represented by chitosan contains a large number of active groups to selectively adsorb heavy metal ions, which provides a possibility for efficient and economical treatment of heavy metal wastewater. The adsorbent was prepared by a combination of in situ-coprecipitation and ethylene glycol diglycidyl ether crosslinking using chitosan as raw material. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometry (VSM). The static adsorption experiments and simulated fixed bed dynamic adsorption experiments were carried out to investigate the adsorption behavior of Pb(II), Cu(II) and Zn(II) by the gel microspheres under different initial pH, contact time and initial concentrations. The results show that: ①CS-EGDE/Fe<sub>3</sub>O<sub>4</sub> gel microsphere has well-developed internal porosity and good magnetic properties; ②The adsorbent can rapidly chelate with heavy metal ions. The main groups are -NH<sub>3</sub> and -OH, and the adsorption of heavy metal ions conforms to quasi-secondary kinetics. The adsorption process can be described by Langmuir isotherm adsorption equation, which is single-layer chemical adsorption; ③Antagonism occurred in the ternary adsorption system, and the competitive adsorption order of heavy metals was Pb(II)>Cu(II)>Zn(II), mainly owing to the difference in the covalent index of the three ions; ④The fixed bed shows good adsorption performance in the treatment of ternary heavy metal simulated wastewater. The adsorption saturation times of heavy metal Pb(II), Cu(II), and Zn(II) were 13, 8, and 2 h, respectively. The study indicates that CS-EGDE/Fe<sub>3</sub>O<sub>4</sub> gel microsphere has good adsorption performance for heavy metals and it is expected to provide a new technical route for heavy metal wastewater treatment.