Kinetic, thermodynamic and isotherm studies for acid blue 129 removal from liquids using copper oxide nanoparticle-modified activated carbon as a novel adsorbent

A novel adsorbent, copper oxide nanoparticle loaded on activated carbon (CuO-NP-AC) was synthesized by a simple, low cost and efficient procedure. Subsequently, this novel sorbent was characterized and identified using different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and laser light scattering (LLS). The effects of some variables including pH, adsorbent dosage, initial dye concentration, contact time and temperature were examined and optimized. The adsorption kinetic data were modeled using the pseudo-first-order, pseudo-second order, intraparticle diffusion and Elovich models, respectively. The experimental results indicated that the pseudo-second-order kinetic equation can better describe the adsorption kinetics. Furthermore, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models were applied for analyzing adsorption equilibrium data of acid blue 129 (AB 129) on the as-prepared adsorbent, which suggested that the Langmuir model provides a better correlation of the experimental data. Also, thermodynamic parameters such as ΔH, ΔS, E_a, S∗, and ΔG were calculated. It was seen that the proposed adsorbent has high tendency and adsorption capacity for AB 129 adsorption in a feasible, spontaneous and endothermic way.