Removal of Nickel from Aqueous Solutions by Natural Bentonites from Slovakia

In this study, the removal of nickel (Ni(II)) by adsorption from synthetically prepared solutions using natural bentonites (Lieskovec (L), Hlinik nad Hronom (S), Jelsovy Potok (JP), and Stara Kremnicka (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 degrees C. Thermodynamic parameters, including standard enthalpy (Delta H-0), Gibbs energy (Delta G(0)), and standard entropy (Delta S-0), 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.

Automated summary

This study investigated the removal of nickel from synthetically prepared solutions using natural bentonites, with experimental results showing that bentonites from JP and SK were most effective for nickel removal. Thermodynamic parameters were calculated, indicating the adsorption process was endothermic and spontaneous. Adsorption capacities and kinetic models were also determined for the different bentonite samples.