The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.
Magnetic biochar nanocomposites were obtained by modification of biochar by zero-valent iron. The article provides information on the impact of contact time, initial Cd(II), Co(II), Zn(II), and Pb(II) ion concentrations, dose of the sorbents, solution pH and temperature on the adsorption capacity. On the basis of experiments, it was found that the optimum parameters for the sorption process are phase contact time 360 min (after this time, the equilibrium of all concentrations is reached), the dose of sorbent equal to 5 g/dm3, pH 5 and the temperature 295 K. The values of parameters calculated from the kinetic models and isotherms present the best match to the pseudo second order and Langmuir isotherm models. The calculated thermodynamic parameters ∆H
0, ∆S
0 and ∆G
0 indicate that the sorption of heavy metal ions is an exothermic and spontaneous process as well as favoured at lower temperatures, suggesting the physical character of sorption. The solution of nitric acid(V) at the concentration 0.1 mol/dm3 was the best acidic desorbing agent used for regeneration of metal-loaded magnetic sorbents. The physicochemical properties of synthesized composites were characterized by FTIR, SEM, XRD, XPS and TG analyses. The point characteristics of the double layer for biochar pHPZC and pHIEP were designated.
<p>Celem niniejszego artykułu jest analiza zjawiska cyberseksu, będącego coraz częściej wybieraną „alternatywą” zaspokajania popędu seksualnego. Przeglądowy charakter pozwolił poddać omawiane zjawisko wnikliwej analizie. Opracowanie opiera się na wnioskach i badaniach naukowców, realizowanych zarówno na gruncie zagranicznym, jak i polskim. Dokonanie obiektywnej oceny wirtualnego seksu oraz wyciągnięcie konstruktywnych wniosków jest rzeczą trudną. Niemniej można postawić tezę, że internetowy seks powoduje wiele pejoratywnych konsekwencji, takich jak: obniżenie się intymności partnerskiej, pogłębiająca się pustka i samotność ludzi oraz uzależnienie. Mimo że Internet daje możliwość stałego kontaktu, a wirtualny stosunek zaspokaja popęd seksualny, nigdy nie zastąpi on realnych relacji i prawdziwych emocji przeżywanych w życiu rzeczywistym. W przypadku cyberseksu, parafrazując słowa Andrzeja Zwolińskiego, jest i będzie on nadal jedynie protezą intymnych spotkań i doświadczeń.</p>
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