Zr4+ ions embedded chitosan-soya bean husk activated bio-char composite beads for the recovery of nitrate and phosphate ions from aqueous solution

Removal of nitrate and phosphate ions using Zr4+ ions embedded chitosan-soya bean husk activated bio-char composite beads (Zr-CS-SAC) was carried out by batch mode to overcome the environmental problems due to eutrophication. The adsorbent was well characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) analysis with energy dispersive X-ray analyzer (EDX), X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller surface analyzer (BET), thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA) etc. The adsorption equilibrium models of Langmuir, Freundlich and D-R isotherms were evaluated and the results described that the Freundlich model was the best for both the adsorbates of nitrate and phosphates ions with respective capacities of 90.09 and 131.29 mg g-1 at 30 °C. Studies on thermodynamic parameters revealed the endothermic and spontaneous nature of the adsorption. Different kinetic models were studied and found that pseudo-second-order kinetic data were well fitted for adsorption process. These results suggested that Zr-CS-SAC composite beads as a promising adsorbent for the removal of nitrate and phosphate ions from water with good removal efficiency, adsorbability, recyclability and non- toxicity.