Piotr Szczepański

In the subject literature, the prevalent opinion is that in the local environment of Pomerania in the 11 ^th century, coins imitating Western European coins were manufactured. This conclusion was based on a discovery made in 1888 in Łupawa near Słupsk. In that location, a several-thousand-specimens large coin assemblage was found; together with silver clumps, bars, and adornments, they were deposited in the final decades of the 11 ^th century. The stamps employed for making these coins bore a resemblance to coinage from Germany, England, Denmark, as well as Bohemia, and were a group distinctive enough for numismatic terminology to adopt the term of “Łupawa imitations”, “Łupawa-type denarii”, or “Łupawa group”. Researchers concordantly classify to this group, predominantly, large series of coins that occur in the hoard of Karwna, Włynkowo, and Gliszcz. Due to the limited access to the Gliszcz and Łupawa coin series, a decision was made that the coin assemblage from a hoard unearthed before the year 1930 in Włynkowo should be analysed. Although we do not know the specific location of this discovery, it is clearly and directly associated to the transport-related role of the River Słupia and the settlement on the periphery of the Słupsk microregion. For each artefact, the share of specific elements was determined using specialist equipment by means of non-model semi-quantitative analysis, with distribution maps for their presence in the analysed microarea of a sample. In cross-section, most of the denarii that occurred in the Włynkowo deposit show a zonal structure with a gradually decreasing percentage of silver, which is the highest in the near-surface levels and, in turn, the lowest within the core characteristic of, depending on the type of alloy, either bronze or brass. Based on the examined Włynkowo assemblage, it can be claimed that we are dealing with a technologically simple mass production of a coin with a silvered surface imitating the full-value silver coin in East Pomerania in the second half of the 11 ^th century.

Five mathematical models for transport description in polymer inclusion membranes (PIMs) were presented and compared via regression analysis. The applicability of the models was estimated through the examination of experimental data of Zn(II), Cd(II), Pb(II), and Cu(II) ions transported by typical carriers. In four kinetic models, a change in the feed and stripping solution volume was taken into account. The goodness of fit was compared using the standard error of the regression, Akaike information criterion (AIC), Bayesian (Schwarz) information criterion (BIC), and Hannan–Quinn information criterion (HQC). The randomness distribution in the data was confirmed via a nonparametric runs test. Based on these quantities, appropriate models were selected.

Two kinetic models which are applied for the description of metal ion transport in polymer inclusion membrane (PIM) systems are presented and compared. The models were fitted to the real experimental data of Zn(II), Cd(II), Cu(II), and Pb(II) simultaneous transport through PIM with di-(2-ethylhexyl)phosphoric acid (D2EHPA) as a carrier, o-nitrophenyl octyl ether (NPOE) as a plasticizer, and cellulose triacetate (CTA) as a polymer matrix. The selected membrane was composed of 43 wt. % D2EHPA, 19 wt. % NPOE, and 38 wt. % CTA. The results indicated that the calculated initial fluxes (from 2 × 10⁻¹¹ up to 9 × 10⁻¹⁰ mol/cm²s) are similar to the values observed by other authors in systems operating under similar conditions. It was found that one of the most frequently applied models based on an equation similar to the first-order chemical reaction equation leads to abnormal distribution of residuals. It was also found that application of this model causes some problems with curve fitting and leads to the underestimation of permeability coefficients and initial maximum fluxes. Therefore, a new model has been proposed to describe the transport kinetics in PIM systems. This new model, based on an equation similar to the first-order chemical reaction equation with equilibrium, was successfully applied. The fit of this model to the experimental data is much better and makes it possible to determine more precisely the initial maximum flux as the parameter describing the transport efficiency.

The effects of structural changes of organophosphorus cationic exchangers on metal-distribution curves (extraction efficiency vs. pH) have been investigated for the recovery of cobalt(II), nickel(II) and manganese(II) from acidic chloride solutions. By using alkyl groups with different branching and hydrophobicity and by including oxygen atoms in the hydrophobic chains of the cationic exchangers, it has been shown that the change of the chemical structure in the hydrophobic chains plays an important role in the extraction behaviours and causes more specifically a shift of the extraction curves to higher or lower pH depending on pK_a values of extracting agents (evaluated by using QSPR calculations), distribution constants of metal–ligand complexes between organic and aqueous phases and the formation constant of the metal–ligand complexes. Based on the present results, interest in the new cationic exchangers synthesized in the present work for cobalt(II), nickel(II) and manganese(II) separation is also discussed.