Adsorptive Removal of Ni(II) Ions from Aqueous Solution by Polyacrylic Acid/Attapulgite Composite Hydrogels

Abstract

Polyacrylic acid/attapulgite (PAA/ATP) composite hydrogels used for removal of heavy metal ions from aqueous solution was synthesized via radical polymerization with acrylic acid (AA) and attapulgite (ATP) modified by hydrochloric acid as adsorbent. Chemical composition of the modified ATP was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) and the morphology of the PAA/ATP hydrogels was characterized by scanning electron microscope (SEM), respectively. The swelling ratio, pH-sensitivity and adsorption performance of Ni (II) ions of the composite hydrogels were studied. The results showed the swelling ratio of the PAA/ATP composite hydrogels was higher than that of PAA hydrogels and the composite hydrogels displayed sensitivity to pH values with a sharp increase of swelling ratio when the pH values increased from 4 to 6. Comparing with PAA hydrogels, the composite hydrogels obtained a larger adsorption capacity of Ni (II) ions, the average adsorption capacity could reach 72.8 mg/g and adsorption ratio could reach 84%.