Removal of Nickel from Aqueous Solutions by Natural Bentonites from Slovakia.

Matej Šuránek,Ljiljana Kljajević,Zuzana Melichová,Snežana Nenadović,Valéria Kureková

doi:10.3390/ma14020282

Abstract

In this study, the removal of nickel (Ni(II)) by adsorption from synthetically prepared solutions using natural bentonites (Lieskovec (L), Hliník nad Hronom (S), Jelšový Potok (JP), and Stará Kremnička (SK)) was investigated. All experiments were carried out under batch processing conditions, with the concentration of Ni(II), temperature, and time as the variables. The adsorption process was fast, approaching equilibrium within 30 min. The Langmuir maximum adsorption capacities of the four bentonite samples used were found to be 8.41, 12.24, 21.79, and 21.93 mg g–1, respectively. The results best fitted the pseudo-second-order kinetic model, with constant rates in a range of 0.0948–0.3153 g mg–1 min. The effect of temperature was investigated at temperatures of 20, 30, and 40 °C. Thermodynamic parameters, including standard enthalpy (ΔH0), Gibbs energy (ΔG0), and standard entropy (ΔS0), were calculated. The adsorption of Ni(II) by bentonite samples was an endothermic and spontaneous process. These results indicated that, of the bentonite samples used, the natural bentonites from JP and SK were most suitable for the removal of nickel from synthetically prepared solutions.

Highlights

IntroductionThe adsorption of Ni(II) by bentonite samples was an endothermic and spontaneous process
The removal of nickel via adsorption onto natural bentonites from four different Slovak deposits was investigated in detail
The adsorption isotherms were described by the Langmuir isotherm model and by the Freundlich isotherm model

Summary

Introduction

The adsorption of Ni(II) by bentonite samples was an endothermic and spontaneous process. These results indicated that, of the bentonite samples used, the natural bentonites from JP and SK were most suitable for the removal of nickel from synthetically prepared solutions. The group of heavy metals posing a potential risk to the environment includes nickel. Nickel (Ni, atomic number: 28) is a silver-white heavy metal, occurring in oxidation states of −1, 0, +1, +2, +3, and +4. Its other sources include metal mining, smelting, fossil fuel combustion, vehicle emissions, domestic, municipal, and industrial waste disposal, fertilizer applications, and organic fertilizers [4].

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Results

Conclusion