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The effect of microstructural changes caused by mechanical modification on adsorption properties of diatomite samples were investigated. The microstructure has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) while the degree of metal adsorption was evaluated by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP AES). The results show that metal sorption capacity of diatomite is considerably improved after mechanical modification and it can be attributed to amorphysation of the material. Immobilization efficiency increased from 22% for untreated to 81% for the treated sample after 5h at BPR 4.This qualifies natural diatomite as a material for wastewater remediation

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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.

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