Chitosan based nano composite adsorbent-Synthesis, characterization and application for adsorption of binary mixtures of Pb(II) and Cd(II) from water.

Composite type adsorbent was prepared by integrating chitosan (Cs) with crosslinked polymethacrylic acid (PMA) and nano sized halloysite nanotube (HNT). The structure of the resulting Cs-PMA/HNT adsorbents was characterized by FTIR, NMR, XRD, TGA, SEM/EDX and rheological properties. These functional adsorbents were used for removal of Pb(II) and Cd(II) as single and binary competitive mixtures from water. There was a significant improvement in adsorption properties of crosslinked PMA in the presence of Cs and HNT. The effect of synthesis parameters such as wt.% of Cs and HNT on swelling and process parameters such as solution pH, adsorbent dosage, contact time and feed concentration on adsorption of metal ions from water were studied in batch experiments. For a feed concentration of 100mg/L of metal ion, an adsorbent dose of 0.25g/L and a solution pH of 6, the Cs-PMA/HNT composite adsorbent containing 4wt% Cs and 3wt% HNT showed an adsorption capacity (mg/g)/removal% of 357.4/89.4 and 341.6/85.4 for single Pb(II) and Cd(II), respectively which reduced to 313.7/78.4 and 303.6/77.3 for the same metal ions in their binary mixtures in water.