Evaluation of structural and charge properties of polyamide nanofiltration membrane

Nanofiltration (NF) is a highly efficient membrane separation process which has various environmental and industrial applications. Nanofiltration membranes are finely porous membranes with specific interesting features, their characterization being important for understanding of the NF processes and for their prediction for practical use. A polyamide thin-film composite NF membrane (AFC 80) was characterized in the present work by two different techniques: modelling of the rejection of uncharged solutes and modelling of the salt rejection. The interpretation of the data from uncharged solutes rejection experiments by using Donnan steric partitioning pore model (DSPM) allows to determine the structural characteristics of the AFC 80 membrane, i.e., effective pore radius (rp), and thickness to porosity ratio ()x/Ak). The experimental data for sodium chloride rejection were used to calculate the effective fixed charge density (MX) by means of an irreversible thermodynamics model (Spiegler–Kedem model) and of a charge model, namely Teorell–Meyer–Sievers (TMS) model. It was found that the membrane charge depends on the salt concentration in solution, this behaviour being attributed to ion adsorption on the membrane. The dependence of the charge density on NaCl concentration obeys a Freundlich isotherm equation

Testing of the method of determination of nitrates using portable analyzer Photometer PF-12

V této práci byla testována metoda stanovení dusičnanů ve vodách s využitím přenosného fotometrického analyzátoru Fotometr PF-12. Výsledky i samotná metoda byly porovnány s průtokovou injekční analýzou (FIA) a spektrofotometricky sledovanou simultánní neutralizační mikrotitrací.In this work, a method to determine NO3− using portable analyzer Photometer PF-12 (Macherey-Nagel, Germany) for analysis of model solutions, and drinking as well as natural water was tested. The obtained results have been compared with those achieved by flow injection analysis and by spectrophotometrically followed simultaneous neutralizing microtitration

Voltametrické chování triazolových fungicidů na elektrodě z borem dopovaného diamantu

Voltammetric behavior of azole fungicides difenoconazole, tebuconazole, and triticonazole was investigated for the first time using boron doped diamond electrode. Oxidation mechanism was also solved. The obtained oxidation signals of particular compounds were utilized for the development of voltammetric methods for their determination. Proposed methods were applied for analysis of real samples, e.g., spiked drinking and natural water, pesticide preparations.Bylo poprvé studováno voltametrické chování triazolových fungicidů difenoconazolu, tebuconazolu a triticonazolu s využitím elektrody z borem dopovaného diamantu. Byl navržen oxidační mechanismus. Získané voltametrické signály byly využity pro vývoj metod stanovení těchto látek, které byly aplikovány při analýze modelových roztoků i vzorků komerčně dostupných pesticidních přípravků