Adsorption of Ni2+ on malic acid modified activated carbon from Phragmites australis

: To tackle the issue of environmental pollution caused by heavy metal ions, a novel malic acid modified activated carbon (denoted as MA-AC) from (the plant) Phragmites australis has been successfully prepared with high Ni 2 + adsorption capacity (38.36 mg / g). The physical and chemical characteristics of MA-AC were evaluated by N 2 adsorption / desorption, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS). The results indicated that the MA-AC has more microporous structures and more oxygen bearing functional groups than the unmodified AC (denoted as AC). The Ni 2 + adsorption behaviors of the adsorbents were investigated by batch experiments, which indicated that the MA-AC showed 38% higher Ni 2 + adsorption capacity than the unmodified AC. The adsorption isotherms and the kinetics of the absorbents agreed well with the Langmuir model and the pseudo-second-order model. The Ni 2 + adsorption mechanisms of MA-AC were investigated by FTIR and XPS analyses. The results from the analyses indicated that the enhanced surface adsorption of Ni 2 + on MA-AC are attributed to the chemistry between the Ni 2 + and the oxygen-containing functional groups on the surface.