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Joanna Krason and Robert Pietrzak

Abstract

The polymer membranes containing 18 wt% of cellulose acetate and different amounts of polyvinylpyrrolidone (PVP) as a cross-linker agent were used in the process of iron and copper ions removal from liquid phase. Depending on the content of PVP (changed from 1 to 4 wt.%) the membrane surfaces were characterised by different hydrophilic character and showed the dominant presence of surface oxygen-containing groups of acidic character. Irrespectively of the concentrations of solvents from which the metal ions had to be removed, the membranes showed better ability to remove Fe3+ ions than Cu2+ ones, and the membrane resistances decreased with increasing content of PVP. After the filtrations of solutions with iron ions the flux recovery ratio took rather high values; this ratio increased with increasing PVP content in the membrane.

Open access

Piotr Nowicki, Wiktor Szymanowski and Robert Pietrzak

Abstract

Two series of functionalised carbonaceous adsorbents were prepared by means of oxidation and nitrogenation of commercially available activated carbon and multi-walled carbon nanotubes. The effect of nitrogen and oxygen incorporation on the textural, surface, thermal and sorption properties of the adsorbents prepared was tested. The materials were characterized by elemental analysis, low-temperature nitrogen sorption, thermogravimetric study and determination of the surface oxygen groups content. Sorptive properties of the materials obtained were characterized by the adsorption of methylene and alkali blue 6B as well as copper(II) ions. The final products were nitrogen- and oxygen-enriched mesoporous adsorbents of medium-developed surface area, showing highly diverse N and O-heteroatom contents and acidic-basic character of the surface. The results obtained in our study have proved that through a suitable choice of the modification procedure of commercial adsorbents it is possible to produce materials with high sorption capacity towards organic dyes as well as copper(II) ions.

Open access

Katarzyna Pietrzak, Wiesława Olesińska, Cezary Strąk, Robert Siedlec and Andrzej Gładki

Abstract

The aim of the work presented in the article was to clarify controversial comments about anti-corrosion and mechanical properties of graphene coatings, deposited on copper substrates. It was designed special experimental cycle comprising: preparation of graphene forms and copper, the observation of layers Cu / GO (rGO) after the thermal reduction processes and oxidative test in air at 150°C temperature and 350 h in time. The resulting coatings and graphene layers were subjected to tribological test for hardness. The observed differences in the continuity of the coverage copper surface by graphene forms, allowed to understand the macroscopic effect of increased hardness and wear resistance layers rGO/Cu.

Open access

Małgorzata Grządziel, Adam Konefał, Wiktor Zipper, Robert Pietrzak and Ewelina Bzymek

Abstract

Verification of calculations of the depth-dose distributions in water, using GEANT4 (version of 4.9.3) and MCNPX (version of 2.7.0) Monte Carlo codes, was performed for the scatterer-phantom system used in the dosimetry measurements in the proton therapy of eye tumours. The simulated primary proton beam had the energy spectra distributed according to the Gauss distribution with the cut at energy greater than that related to the maximum of the spectrum. The energy spectra of the primary protons were chosen to get the possibly best agreement between the measured relative depth-dose distributions along the central-axis of the proton beam in a water phantom and that derived from the Monte Carlo calculations separately for the both tested codes. The local depth-dose differences between results from the calculations and the measurements were mostly less than 5% (the mean value of 2.1% and 3.6% for the MCNPX and GEANT4 calculations). In the case of the MCNPX calculations, the best fit to the experimental data was obtained for the spectrum with maximum at 60.8 MeV (more probable energy), FWHM of the spectrum of 0.4 MeV and the energy cut at 60.85 MeV whereas in the GEANT4 calculations more probable energy was 60.5 MeV, FWHM of 0.5 MeV, the energy cut at 60.7 MeV. Thus, one can say that the results obtained by means of the both considered Monte Carlo codes are similar but they are not the same. Therefore the agreement between the calculations and the measurements has to be verified before each application of the MCNPX and GEANT4 codes for the determination of the depth-dose curves for the therapeutic protons.