P. Podkościelny

Adsorption of phenols from aqueous solutions: Equilibria, calorimetry and kinetics of adsorption

The brief theoretical description of the phenols adsorption from aqueous solutions on carbonaceous adsorbents, i.e. activated carbons (ACs) and activated carbon fibers (ACFs) has been presented. The description includes adsorption equilibria, calorimetry as well as kinetics of adsorption. The generalized Langmuir-Freundlich (GLF) isotherm equation has been used to study of the cooperative effect of the surface heterogeneity and the lateral interactions between the admolecules. Theoretical isosteric heats of adsorption connected with the GLF model have been estimated too. Knowledge of both adsorption equilibria and heats of adsorption is fundamental for adequate description of any adsorption process. To correlate the kinetic data of the studied systems, the theoretical equations developed from Statistical Rate Theory (SRT) of Interfacial Transport were applied. The most advantageous of the proposed model of calculations is the set of common parameters appearing in each type of expressions, which significantly extends the possibility of their interpretation. Theoretical studies were fully reviewed using the literature experimental adsorption data. They included the data of phenols adsorption both on ACs and ACFs surfaces.

A new approach to determination of the parameters describing liquid adsorption on the solid surfaces

Abstract A new approach for determining the surface phase capacity on homogeneous and heterogeneous solid surfaces has been proposed. This approach is based on the statistical analysis of the errors made applying the Everett and Langmuir–Freundlich equations. The Everett equation was used for evaluation of the surface phase capacity formed on homogeneous solid surfaces, however, the Langmuir–Freundlich one was used in the case of adsorption on heterogeneous surfaces. Calculations were made assuming the linear regression model and within it making a statistical analysis of the errors resulting from using these equations. In terms of the proposed approach we can obtain more reliable thermodynamic values characterizing the adsorbed phase and, therefore, predict more accurately the adsorption mechanism in the systems under consideration.

Fractal approach of adsorption from liquid mixtures on silica gel

Abstract The analysis of adsorption from binary liquid mixtures on silica gels in terms of the fractal geometry approach has been presented. This analysis is based on the relationship between monolayer surface phase capacity and molecular cross area of the preferentially adsorbed component of binary mixtures: aliphatic alcohol (1)+benzene (2) and aliphatic ketone (1)+benzene (2). It has been proved that the linear form of Langmuir–Freundlich (LF) isotherm is proper to calculate the capacity of the surface phase. The surface fractal dimension for the preferentially adsorbed compounds (i.e. alcohols or ketones) was calculated by using linear equation proposed by Pfeifer and Avnir (PA). All calculations were made assuming the linear regression model and within it making a statistical analysis of the errors resulting from using these equations. In terms of the proposed approach we can obtain reliable values of surface fractal dimensions D , that lie in the interval: 2 D

New Ion Exchangers Based on Copolymers: 2,3-(2-Hydroxy-3-Methacryloyloxypropoxy)Naphthalene–Styrene

Synthesis and characterization of the new polymeric ion exchangers with thiol and sulfonyl hydroxide groups are presented. These new sorbents were also compared with polymeric microspheres possessing methylenethiol groups on the surface presented previously. The polymeric cation ion exchangers in the form of microspheres were obtained by the suspension-emulsion polymerization tetrafunctional monomer: 2,3-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,3-NAF.DM) with styrene (St). Next, multistage modification introducing sulfur-containing group (thiol or sulfonyl hydroxide or methylenethiol) on the surface of polymeric matrices was made. In order to obtain sulfonyl hydroxide derivatives the matrices were performed as follows: the parent microspheres were treated by H2SO4 (Method I) or with the addition of oleum (Method II). The thiol groups were introduced in a two-stage reaction. In the first stage chlorosulfonation of parent microspheres in the presence of chlorosulfonic acid was carried out. Finally, the reduction of modified microspheres by using SnCl2·2H2O was conducted. The sulfur group content (elemental analysis, scanning electron microscope EDX SEM), thermal properties (thermogravimetric analysis), porous structure as well as the swelling characteristics of the functional beads were examined. The surface texture was also visualized by the AFM method.