Adsorption performance and mechanism of cadmium by guava leaf/MgAl-LDH composites
An environmentally friendly and novel composite adsorbent,Gl/MgAl-LDH,was obtained by Guava leaf(Gl)and MgAl-Layered double hydroxide(MgAl-LDH)composite with a co-precipitation method,and Gl/MgAl-LDH was used to adsorb cadmium(Cd)in solution.The adsorption performance of Gl/MgAl-LDH towards Cd2+was investigated by adsorption kinetics and isotherm,its properties and adsorption mechanism were studied by different characterization instruments.The experimental results showed that Gl/MgAl-LDH could reach the adsorption equilibrium at 60 min,and the adsorption amount was 37.50 mg·g-1,which was higher than that of MgAl-LDH or Gl.Adsorption process of Cd2+onto Gl/MgAl-LDH conformed to the proposed secondary kinetic and Freundlich models with a maximum adsorption amount of 68.43 mg·g-1.Characterization results showed that the complex reaction occurred between metal ions on LDH and organic functional groups on Gl,and LAD was successfully anchored on Gl surface.The appearance of the spectral peaks of elemental Cd in the XPS spectra of the adsorbed Gl/MgAl-LDH confirmed the effective adsorption of Cd2+onto the material.The main mechanisms of Cd2+removal by Gl/MgAl-LDH were adsorption precipitation and organic complexation.The results of this study provide a reference for the resource utilization of biomass as an adsorbent.
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