RESUMO
The nature of ionic liquids (ILs) facilitates their analysis by ion chromatography which, unlike conventional high-performance liquid chromatography, enables analysis both of cations and anions. This paper describes a pioneering ion-chromatographic investigation of IL cations and statistical evaluation of quantitative structure-retention relationships with the objective of predicting the molecular mechanism responsible for retention. Eleven ionic liquid imidazolium and pyridinium cations were analyzed on a CS15 cation-exchange column by isocratic elution with acetonitrile-methanesulfonic acid mixtures. Structural descriptors of the cations obtained from molecular modeling were used to describe their hydrophobicity as determined by chromatography. The most statistically significant were three-term QSRR regression equations relating log k(w) to analyte n-octanol-water partition coefficient (log P), dipole moment (µ), solvent accessible surface area (A(SAS)), and hydration energy (HE). They indicate the important role of both hydrophobic and polar the retention of ILs on the CS15 column.
RESUMO
The chemical speciation of Cd, Cu, Pb, Cr and Ni in Torun municipal sewage sludge is investigated with addition of a natural sorbent (clinoptilolite rock). The total contents of the heavy metals in the sludge are substantially lower than the corresponding limits established by European or Polish legislation excepting nickel only. But the metals concentrations excepting lead exceed significantly the natural background (average contents in soils and in the Earth's crust) in dozens. Application of the sequential chemical extraction indicated that the metals in the sewage sludge are bound mainly (over 50%) in the residual fraction. The metals form the following order by parts of the mobile form: Ni> Cd>> Cr> Cu>> Pb. Addition of the clinoptilolite to the sludge leads to the metals contents fall in all four fractions of the sequential procedure. Concentrations of mobile forms of cadmium, chromium, copper and nickel decrease by 87, 64, 35 and 24%, respectively, as a result of addition of 9.09% of the clinoptilolite. The total decreases of the metals amount after 9.09% clinoptilolite addition to the sludge are around 11, 15, 25, 41 and 51% for copper, nickel, chromium, cadmium and lead, respectively.
Assuntos
Metais Pesados/análise , Metais Pesados/química , Esgotos/química , Zeolitas/química , Fenômenos Químicos , Físico-QuímicaRESUMO
The main aim of this work is focused therefore on water quality assessment of the Vistula river and its primary tributaries. The study presents the analytical results of the contamination level of different organic and inorganic pollutants as well as the chemometric evaluation of the entire data set. A broad spectrum of compounds have been determined, including pesticides, polichlorinated biphenyls (PCBs), phenols, polycyclic aromatic hydrocarbons (PAHs), heavy metals, inorganic ions and some aggregate parameters like BOD. Majority of the organic xenobiotics have been analyzed for first time in the Vistula region on a large, long-term scale. Chemometric evaluation allowed the determination of natural clusters and groups of monitoring locations with similar pollution character. Chemometric analysis confirmed the classification of water purity of the Vistula River basin is related to the land utilization character in this region.