Investigating the equilibrium and adsorption kinetics for the removal of Ni (II) ions from aqueous solutions using adsorbents prepared from the modified waste newspapers: A low-cost and available adsorbent

Abstract

The aim of this study was to remove nickel from aqueous solutions using modified waste newspapers (MWNPs). Nickel as a heavy metal has shown toxicity and carcinogenic effects. Removal of this metal from aqueous solutions into modified waste newspaper was carried out in this batch experiment, accompanied by investigating the parameters of contact time, pH, adsorbent dose, and initial concentration of nickel. Aiming to broaden the horizon of the adsorption mechanism, experimental data were evaluated by Langmuir, Freundlich and Temkin isotherm equations. The results demonstrated the Optimum dose of adsorbent, pH, initial concentration, and contact time to be 1 g, 6, 5 mg/L and 120 min, respectively. The process of nickel removal followed the procedures of Langmuir isotherm model (R2 = 0. 0.99; maximum adsorption capacity 32.22 mg/g (average value from various temperature)) and pseudo second for kinetics. Besides, thermodynamic studies were conducted to explore the adsorption of Ni (II) onto MWNPs with the focus on the influence of temperature on this process. The spontaneity and endothermicity of Ni (II) adsorption process were identified based on the negative free energy value and positive enthalpy change. The high adsorption efficacy of modified waste paper in removal of nickel in the aqueous solution was approved, making it an eco-friendly, convenient, and cost-effective option in industrial effluent treatment.