Nanocomposites of immobilized nano-zirconia on low-cost activated carbon derived from hazelnut shell for enhanced removal of 3-Nitro-4-Hydroxy-Phenylarsonic acid from water

3-Nitro-4-hydroxy-phenylarsonic acid (NHPA) as a veterinary drug can degraded into highly toxic inorganic arsenic and will be harmful to environment and food safety. Nanocomposites for the uptake of NHPA were obtained by efficiently immobilizing the nano-sized zirconium oxide onto hazelnut shell-based activated carbon using pyrolysis method. We found that the pyrolysis temperature played a crucial role in the adsorptive performances of the nanocomposites. The prepared nanocomposite at pyrolysis temperature of 600 °C with a mass ratio of ZrOCl2/activated carbon of 1:3 exhibited a fast adsorption equilibrium for NHPA within 5 min, excellent adsorption capacity of 825.7 mg g−1 and the higher adsorption capacity with the increase in temperature from 20 to 45 °C across a pH range of 4–6. 90% of the NHPA uptake was sustained in the NaNO3 solution of 0.7 mol L−1. The adsorption data were well simulated by the Langmuir and pseudo-second order equations. Thermodynamic parameters suggested that the uptake of the NHPA occurred spontaneously (ΔG0<0) with an endothermic characteristic (ΔH0>0). A synergetic effect of electrostatic attraction, As–O–Zr surface coordination and π–π interaction is the main adsorption mechanism of the nanocomposites for the removal of the NHPA.