Małgorzata Gnus

Removal of boron from aqueous solution by composite chitosan beads

ABSTRACT Various metal-oxide nanoparticles and chitosan were blended to form new adsorbents (M-Oxide-CTS) for removing boron from aqueous solutions in a batch system. The maximum boron adsorption capacity (q = 7.8 mg/g) was reached at pH = 4 within 5 min. Calculations based on Langmuir, Freundlich, and Dubinin–Radushkevich models showed the heterogeneous and physical nature of boron adsorption on M-Oxide-CTS. Modeling of the thermodynamic date indicated the nonspontaneous and exothermic process. The pseudo-second-order model adequately described the boron adsorption on M-Oxide-CTS. Desorption by means of alkaline solution at pH = 12 was carried out successfully.

The influence of oxygen conditioning effect on the permeation properties of polyaniline membranes

ABSTRACT The effect of oxygen conditioning on the performance of polyaniline (PANI) membranes is presented and discussed. The presence of the conditioning effect in such kind of polymer matrix was confirmed by measuring a variation in spin concentration using electron paramagnetic resonance (EPR) spectroscopy. The observed decrease in spin concentration indicates the presence of the dissolved oxygen incompletely removed from PANI matrix. After the prolonged contact between oxygen and PANI membrane, a pronounced decrease in membrane’s selectivity was observed, which may be explained by the firm and permanent interaction between oxygen molecules and nitrogen paramagnetic centers of PANI and could be considered as a kind of PANI irreversible doping process.

Permeation of ethanol and water vapors through chitosan membranes with ferroferric oxide particles cross-linked by glutaraldehyde and sulfuric(VI) acid

ABSTRACT Chitosan membranes filled with different amount of ferroferric oxides and cross-linked by two different agents, i.e. sulfuric acid or glutaraldehyde, were prepared and the influence of iron oxide and cross-linking agents on ethanol and water permeation has been discussed. Ethanol and water vapors permeation rates were determined using the measuring cell method and mass transport coefficients were evaluated. It was found that permeation of water for both types of chitosan membranes after addition of magnetite gradually increased. Furthermore, the difference between ethanol/water permeation coefficients was larger for glutaraldehyde cross-linked membranes (CHGA) than for sulfuric acid cross-linked membranes (CHSA).

The influence of metal oxides on the separation properties of hybrid alginate membranes

ABSTRACT Alginate membranes filled with different metal oxide particles were prepared and the influence of the presence of different amounts of Fe3O4, ZnO, and Ag2O particles on ethanol and water permeation was discussed. Ethanol and water vapour permeation rates were determined using the measuring cell method, and the mass transport coefficients were evaluated. It was found that the highest transport parameters were obtained for membranes with the highest metal oxide content. Furthermore, the highest flux, equal 8.49 kg·m−2·h−1, was obtained for the alginate membrane filled with 15 wt% of silver oxide particles, while the greatest selectivity coefficients were noted for membranes containing magnetite. In this case, for the alginate membrane with 15 wt% of magnetite content, the selectivity coefficient reached the best value of 108.15.