Ústav fyzikální a spotřební chemie

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Study of plasma activated water effect on heavy metal bioaccumulation by Cannabis sativa Using Laser-Induced Breakdown Spectroscopy
(Elsevier, 2024-09-15) Čechová, Ludmila; Holub, Daniel; Šimoníková, Lucie; Modlitbová, Pavlína; Novotný, Karel; Pořízka, Pavel; Kozáková, Zdenka; Krčma, František; Kaiser, Jozef
Contamination of the environment with toxic metals such as cadmium or lead is a worldwide issue. The accumulator of metals Cannabis sativa L. has potential to be utilized in phytoremediation, which is an environmentally friendly way of soil decontamination. Novel non-thermal plasma-based technologies may be a helpful tool in this process. Plasma activated water (PAW), prepared by contact of gaseous plasma with water, contains reactive oxygen and nitrogen species, which enhance the growth of plants. In this study, C. sativa was grown in a short-term toxicity test in a medium which consisted of plasma activated water prepared by dielectric barrier discharge with liquid electrode and different concentrations of cadmium or lead. Application of PAW on heavy metal contaminated C. sativa resulted in increased growth under Pb contamination as was determined by ecotoxicology tests. Furthermore, the PAW influence on the bioaccumulation of these metals as well as the influence on the nutrient composition of plants was studied primarily by applying Laser-induced breakdown spectroscopy (LIBS). The LIBS elemental maps show that C. sativa accumulates heavy metals mainly in the roots. The results present a new proof-of-concept in which PAW could be used to improve the growth of plants in heavy metal contaminated environment, while LIBS can be implemented to study the phytoremediation efficiency.
Physico-Chemical Aspects of Metal–Fulvic Complexation
(MDPI, 2024-05-13) Klučáková, Martina; Krouská, Jitka; Kalina, Michal
The interactions of metal ions with fulvic acids were investigated from the point of view of the thermodynamic aspects of complexation as well as the size and charge of the formed complexes. Thermodynamic aspects were studied by means of isothermal titration calorimetry. Particle size distribution was determined by the method of dynamic light scattering and charge by the measurement of zeta potential. Complexation resulted in changes in particle size and charge. The particle size distribution was trimodal for fulvic acids and bimodal for fulvic complexes with calcium and magnesium, while copper–fulvic complexes had only one size fraction. The compensation of the negative charge of carboxylic and phenolic functional groups by positively charged metal ions resulted in an increase in zeta potential which became closer to zero in the case of copper–fulvic complexes. However, all metal–humic complexes behaved as colloidally unstable, which resulted in visually observable sedimentation. Calorimetric measurements provided positive values for changes in enthalpy, which indicated endothermic processes. In contrast, quantum chemical calculations as well as experiments with model compounds provided negative values indicating exothermic processes. Changes in Gibbs energy were determined as negative and changes in entropy as positive.
Physicochemical Properties of Tungsten Trioxide Photoanodes Fabricated by Wet Coating of Soluble, Particulate, and Mixed Precursors
(MDPI, 2024-02-01) Chittoory, Valli Kamala Laxmi Ramya; Filipská, Markéta; Bartoš, Radim; Králová, Marcela; Dzik, Petr
Advanced oxidation processes are emerging technologies for the decomposition of organic pollutants in various types of water by harnessing solar energy. The purpose of this study is to examine the physicochemical characteristics of tungsten(VI) oxide (WO3) photoanodes, with the aim of enhancing oxidation processes in the treatment of water. The fabrication of WO3 coatings on conductive fluorine-doped tin oxide (FTO) substrates was achieved through a wet coating process that utilized three different liquid formulations: a dispersion of finely milled WO3 particles, a fully soluble WO3 precursor (acetylated peroxo tungstic acid), and a combination of both (applying a brick-and-mortar strategy). Upon subjecting the WO3 coatings to firing at a temperature of 450 degrees C, it was observed that their properties exhibited marked variations. The fabricated photoanodes are examined using a range of analytical techniques, including profilometry, thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), and voltammetry. The experimental data suggest that the layers generated through the combination of particulate ink and soluble precursor (referred to as the brick-and-mortar building approach) display advantageous physicochemical properties, rendering them suitable for use as photoanodes in photoelectrochemical cells.
Free-Standing Bacterial Cellulose/Polypyrrole Composites for Eco-Friendly Remediation of Hexavalent Chromium Ions
(American Chemical Society, 2024-05-16) Stříž, Radim; Minisy, Islam; Bober, Patrycja; Taboubi, Oumayma; Smilek, Jiří; Kovalčík, Adriána
Drinking water quality requirements are getting stricter but water sources are limited. Therefore, effective ways to purify it must be developed. In order to remove toxic Cr(VI) from wastewater, efficient, nontoxic, sustainable, resilient biocomposites based on bacterial cellulose (BC) and polypyrrole (PPy) have been fabricated. The free-standing BC/PPy composites, allowing easy handling during and after water treatment, were successfully prepared by the oxidative polymerization of pyrrole on the BC surface. The variation in the physical state of BC sheets used for coating by PPy was done to study the rheological properties and Cr(VI) removal capacity. Characterization techniques like FTIR, SEM, BET, thermogravimetric analysis, and rheological analyses established the morphology and structural properties of the prepared biocomposites. The physical state of the bacterial cellulose used for the coating by PPy positively affected the mechanical and thermal stabilities of the resulting BC/PPy composites but had almost no effect on the removal capacity of hexavalent chromium. The free-standing BC/PPy composites reached a specific surface area of 61.96 m2 g–1 and a pore volume of 0.097 cm3 g–1, showing more than a threefold increase compared to neat BC sheets. The coating of BC by PPy markedly improved the maximum adsorption capacity of Cr(VI). The experimental Cr(VI) adsorption data fitted using Langmuir’s isotherm model indicated homogeneous monolayer adsorption of Cr(VI) ions onto the BC/PPy surface. The Cr(VI) maximum adsorption capacity of BC/PPy composites was determined to be 294.1 mg g–1. Furthermore, the BC/PPy composites were proved to be excellent catalysts for the photocatalytic reduction of toxic Cr(VI) into nontoxic Cr(III) ions. These results suggest that the free-standing BC/PPy composites could be used as alternative materials for eco-friendly remediation of hexavalent chromium ions from wastewater.
Novel highly stable conductive polymer composite PEDOT:DBSA for bioelectronic applications
(Springer Nature, 2023-05-15) Tumová, Šárka; Malečková, Romana; Kubáč, Lubomír; Akrman, Jiří; Enev, Vojtěch; Kalina, Lukáš; Šafaříková, Eva; Pešková, Michaela; Víteček, Jan; Vala, Martin; Weiter, Martin
In this work, a novel conductive polymer composite PEDOT:DBSA for bioelectronic applications was prepared and optimized. The novel PEDOT:DBSA composite possesses superior biocompatibility toward cell culture and electrical characteristics comparable to the widely used PEDOT:PSS. The cross-linking processes induced by the cross-linker GOPS, which was investigating in detail using Fourier transform Raman spectroscopy and XPS analysis, lead to the excellent long-term stability of PEDOT:DBSA thin films in aqueous solutions, even without treatment at high temperature. The electrical characteristics of PEDOT:DBSA thin films with respect to the level of cross-linking were studied in detail. The conductivity of thin films was significantly improved using sulfuric acid posttreatment. A model transistor devicebased on PEDOT:DBSA shows typical transistor behavior and suitable electrical properties comparable or superior to those of avaible conductive polymers in bioelectronics, such as PEDOT:PSS. Based on these properties, the newly developed material is well suitable for bioelectronic applications that require long-term contact with living organisms, such as wearable or implantable bioelectronics.

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