Abstract

NaOCl modified zeolite supported carbon nanotubes (CNTs) were treated with hydrogen peroxide, then
oxidized with nitric acid finally with KMnO4, after modification they were employed as adsorbents for Ni (II)
ions removal. The CNTs were characterized by Fourier transform infrared, scanning electron microscope,
transmission electron microscope, and Raman spectroscopy and thermogravimetric analysis. The adsorption
characteristics were explored using well-established and effective parameters including the effect of pH, contact
time, adsorbent dosage, initial metal ion concentration and temperature. Optimum adsorption of Ni (II) was
observed at pH 6.0. Kinetic studies revealed that the adsorption data fit well to pseudo-second-order model with
high correlation coefficient. Langmuir model gives a better fit than the Freundlich and Dubnin–Radushkevich
models. Thermodynamic properties, i.e., ∆G°, ∆H° and ∆S° showed that adsorption of Ni (II) onto CNTs were
endothermic, spontaneous and feasible in the temperature range of 293-313 K.