Aim: The isotherms of the adsorption of nickel (Ni) (II) ions from model aqueous solutions with the initial concentration of metal ions from 0 to 1500 mg/dm 3 by crushed bark, wood sawdust, and leaves of trees of Acacia auriculiformis in static mode are obtained. It has been established that crushed acacia bark has the largest adsorption capacity with respect to Ni II ions (7 mg/g), and the lowest adsorption capacity has acacia leaves (4 mg/g). Adsorption isotherms were calculated using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Flory-Huggins, Harkins-Jura, and Frenkel-Halsey-Hill models. Materials and Methods: The sorption properties of leaves, sawdust of wood, and crushed bark of A. auriculiformis were studied in the static adsorption regime using model aqueous solutions of Ni sulfate (II) with initial concentrations of Ni 2+ ions from 0 to 1500 mg/dm 3. Results: It is found that the isotherms of the adsorption of Ni ions by leaves, wood sawdust, and crushed bark are most adequately described by the Dubinin-Radushkevich model with the approximation coefficients R 2 = 0.988, R 2 = 0.988, and R 2 = 0.982, respectively, indicating that the process takes place both in the pores and on the surface of sorption material. The thermodynamic parameters of the adsorption process are calculated. Conclusions: The obtained values of Gibbs energy ΔG and the adsorption energy E indicate that the limiting adsorption stage of Ni (II) ions by A. auriculiformis components is physical adsorption.

No abstract

Aim and Scope: One of the priority areas of chemistry and ecology is the receipt of highly effective, cheap, and accessible sorption materials. The waste from industrial and agricultural production is considered as the sources of such sorption materials. In connection with the foregoing, modified sorption materials based on birch leaves (Betula pendula) were prepared by surface treatment with the solutions of sulfuric acid at the concentrations of 1-5% and their sorption properties were studied with respect to phenol in the static adsorption regime. [1] Material and Methods: The study of the sorption properties of materials was carried out in the static adsorption regime on model systems. Result and Discussion: Sulfuric acid-modified birch leaves were obtained by the processing of material surface with the solutions of sulfuric acid at the concentrations of 1, 2, 3, 4, and 5%. Sorption properties of native and modified sorption materials were studied with respect to phenol in the static adsorption regime. They created the isotherms of phenol sorption by studied materials. It was found that the process of phenol sorption by native birch leaves at the temperature of 25°C is best described by the Dubinin-Radushkevich equation, and at 35°C and 45°C by Langmuir's equations, while the process of phenol sorption by modified birch leaves at all three temperatures is best described by Temkin's equations.Conclusion: Thermodynamic constants of the phenol sorption process by native and modified birch leaves have been calculated. It has been established that the processes of phenol sorption by native and modified birch leaves refer to physical processes (according to modulus: E < 8 kJ/mol, ΔH < 100 kJ/ mol, ΔG < 20 kJ/mol) with maximum sorption capacities of 0.06 mmol/g and 0.128 mmol/g, respectively, at 25°C.

Adsorption of ions of nickel on alternative sorption material - needles of Siberian larch (Larix sibirica) is investigated at temperatures of 20, 30 and 40 0C. The maximum sorption capacities of needles of Larix sibirica in relation to ions of nickel (II) at temperatures of 20 are determined °C, 30° C, 40° C which made 0,80 mmol/g (47,2 mg/g), 0,87 mmol/g (51,3 mg/g) and 0,92 mmol/g (54,3 mg/g) respectively. Isotherms of adsorption are received and shortchanged with use of models of Langmuir, Friendlich, Temkin and Dubinin-Radushkevich. It is defined that process of adsorption of ions of Ni2+ at a temperature of 20the ° C is best of all described by Friendlich's model (R2 = 0,983), and at temperatures of 30° C and 40° C - the Langmuir model (R2 = 0,995 and 0,996 respectively). By the carried-out calculations it is defined that process of adsorption of ions of Ni2+ needles of Larix sibirica treat processes of physical adsorption as values of energy of adsorption have size less than 8 kJ/mol, and values of energy of Gibbs demonstrate spontaneous course of physical adsorption. Processing of kinetic dependences of processes of adsorption of ions of nickel (II) Larix sibirica needles at three temperatures within diffusive model defined the limiting stages of processes - the mixed diffusion.

No abstract