Nickel Nanoparticles (NiNPs) as Potential Adsorbent for Acidic Dyes from Aqueous Solutions

Abstract

In the present research study nickel nanoparticles (NiNPs) were prepared via reduction method. The NiNPs were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) is related to the particles surfaces and different elements presents as well as the particles size. The adsorption of Acid orange 8 (AO8) and Acid blue 25 (AB25) dyes onto NiNPs nanoparticles were performed. The effect of various parameters of adsorption, adsorbent dosage, contact time, temperature, and initial dye concentration were studied. The pH for both the adsorbed dyes was kept 1 to 4 with dosage 20 mg for both dyes respectively. The best adsorption kinetic model was pseudo second order kinetics for both dyes with closed unity value of R². Among the applied (Temkin, Freundlich, and Langmuir) isotherm models, Langmuir isotherms followed both dyes which show chemisorption process. The thermodynamic parameters indicate that the standard change in enthalpy (ΔH°) is –8.46 and –7.54 kJ/mol for AO8 and AB25, respectively, indicates the exothermic adsorption. Isotherm models process for both dyes. While the positive standard change entropy (ΔS°) is 0.029 kJ/K for both dyes show disorder during adsorption process. The spontaneous adsorption process is due to free energy (ΔG°) –1.375 and –2.173 kJ/mol values at temperature of 333 K for both acidic dyes respectively. In the view of the above experimental results, suggested that NiNPs could be used a potential adsorbent for the removal of the acidic dyes from the aqueous solutions.