Preparation of magnetic chitosan/polyaniline nanocomposite for efficient remediation of nitrate and phosphate from water

A gel comprising of N-(2-hydroxyethyl)acrylamide (HEAAm), N,N'-methylenebis(acrylamide) (MBA), chitosan (CS), and polyaniline (PANI) made through microwave irradiation was evaluated for effective removal of nitrate and phosphate from water. The material was transformed into a nanocomposite by incorporation of magnetite (Fe3O4) nanoparticles. The nitrate and phosphate removal capacity of the nanocomposite was also evaluated in order to understand the effect of the presence of Fe3O4 on the adsorption efficiency of the gel. The nanocomposite exhibited enhanced adsorption capacity of 55.24 mg g- 1 towards nitrate when compared to the value of 44.5 mg g- 1 for the neat gel without nanoparticles. Also, the phosphate removal was enhanced from 51.4 to 60.60 mg g- 1 due to the presence of Fe3O4 nanoparticles. The enhanced adsorption capacity of the nanocomposite is attributed to the increased surface area of the adsorbent (32.53 m2 g- 1) arising from the contribution of the Fe3O4 nanoparticles embedded in the polymer matrix; as evidenced by surface area measurements. The superparamagnetic nature of the nanocomposite arising due to the presence of magnetite nanoparticles facilitates easy removal of the adsorbent after use during purification process. The mechanism of adsorption is confirmed to be the electrostatic interaction between the active sites on the nanocomposite and the adsorbate anions as indicated by XPS studies. The extent of adsorption and desorption as indicated by % desorption data and adsorption capacity values remained unchanged for about 5 cycles indicating the reusability potential of the material.