Krzysztof Karon

Carbazole electrochemistry: a short review

Carbazole and its derivatives have become important materials for optoelectronic applications in recent years. In this work, we have collated information on the oxidation of carbazole and its derivatives. Knowledge of their electrochemical properties affords insight into the mechanisms for their oxidation and reduction as well as possible subsequent reactions. This knowledge therefore provides the basis for evaluating the stabilities of these materials and for designing novel carbazole-derived materials with desired properties as well as new devices.

Electrochemically induced synthesis of poly(2,6-carbazole)

The formation of a poly(2,6-carbazole) derivative during an electrochemical polymerization process is shown. Comparison of 3,5-bis(9-octyl-9H-carbazol-2-yl)pyridine and 3,5-bis(9-octyl-9H-carbazol-3-yl)pyridine by electrochemical and UV-Vis-NIR spectroelectrochemical measurements and DFT (density functional theory) calculation prove the formation of a poly(2,6-carbazole) derivative. Both of the compounds form stable and electroactive conjugated polymers.

New, hybrid pectin-based biosorbents.

ABSTRACT In this work hybrid pectin-based biosorbents with secondary polysaccharide additives (gellan, carob and xanthan gum, ratio to pectin 1:1, 1:1 and 1:3, respectively) were obtained at two temperatures. The presence of these additives in prepared beads was confirmed by Raman spectra. The SEM micrographs show better homogeneity of blends and grater differences between structures of beads with various additives obtained at higher temperature. The sorption capacity of our hybrid biosorbents as well as sole pectin sorbent is rather the same, and equals 0.85 and 0.70 mmol/g for lead and cadmium, respectively, in pH 4–6.

Hybrid pectin-based biosorbents for zinc ions removal

In this paper, a set of the hybrid biosorbents, made of pectin and polysaccharide additives (arabic, tragacanth, guar, karaya, xanthan, gellan, carob gums, agar-agar) or lecithin (phospholipid), was investigated and tested for zinc ions removal. The immobilization of the polysaccharides into the pectin matrix was proved by the IR spectroscopy. The structure of the working biosorbents was observed in SEM micrographs. The influence of the additive type and pH on the sorption properties and swelling index was investigated. The maximum sorption capacities were achieved in pH above 4 and ranged from 17.7 to 25.4mg/g for lecithin and xanthan gum as additives, respectively. The results show that the hybrid pectin-based beads are promising biosorbents for zinc removal from aqueous solutions.

A versatile method for direct determination of iron content in multi-wall carbon nanotubes by inductively coupled plasma atomic emission spectrometry with slurry sample introduction

Carbon nanotubes (CNTs), due to their unique combination of physicochemical properties, are continuously considered as one of the most interesting materials in contemporary science and industry. Their applicability depends on physical properties, such as number of walls, morphology, diameter and length (aspect ratio), but also on the content of carbonaceous and metallic contaminants (typically present as encapsulated catalyst nanoparticles from catalytic Chemical Vapor Deposition). Therefore, especially for medical and biomedical applications, the concentration of metallic impurities or modifiers should be monitored. In this paper, an inductively coupled plasma atomic emission spectrometry (ICP-AES) technique with slurry nebulization is proposed for direct determination of iron in multi-wall carbon nanotubes (MWCNTs). Slurries of MWCNTs are prepared in a 1% solution of Triton X-100, ultrasonicated to ensure their homogeneity and measured by the ICP-AES apparatus. The optimal range of MWCNTs slurry concentration and plasma radiofrequency (RF) power are established as 40–500 mg L−1 and 1.0 kW, respectively. The precision of the method does not exceed 1.5% of the mean values. Validation of the method is based on the fact that Fe is partly leached from the slurry and the assumption that iron in the leachate gives the same response in ICP-AES as iron in the residual MWCNTs slurry. This behavior was proved by summing both results for Fe (determined in the leachate and in the slurry of post-leaching nanotubes), which always yielded the same total amount of Fe for different degrees of leaching and this value was in full agreement with the iron content in the original, tested sample, as determined by the proposed slurry method. Taking into account all the examinations and obtained results, it can be concluded that the proposed method is applicable for fast, versatile, direct, and simple quantitative analysis of iron in MWCNTs and potentially other nanoallotropes produced by c-CVD.

A Method for Determination of Metals in Hybrid Metal Oxide/Metal-Carbon Nanotubes Catalysts

Carbon nanotubes (CNTs), due to their special structure and unique properties, are still one of the most interesting materials for scientists. Recently, carbon nanotubes were proposed as a new type of carbon support for catalysts. Fe, Pt, Ni, Co, and other metals anchored to CNTs are used in various reactions. Due to the fact that production processes are usually unpredictable and the total amount of metal/metal oxide deposited on the CNTs may only be estimated, the methods for examining the chemical composition are necessary. In this study, fast and simple inductively coupled plasma atomic emission spectrometry (ICP-AES) with slurry nebulization was proposed for metal content determination in hybrid CeZrO2/CNT, Ni-CeZrO2/CNT, and Ni/CNT materials. Slurries were prepared by 30 min ultrasonication of appropriate amount of investigated material in 1% Triton X-100 solution. Optimal range of slurry concentration and optimal RF plasma power were established (40–400 mg L−1, 1.2 kW, resp.). Obtained results proved that this method may be applied for determination of Ce, Zr, and Ni in hybrid CNT-based materials.

Sorption studies of heavy metal ions on pectin-nano-titanium dioxide composite adsorbent

ABSTRACT The Cu(II), Cd(II), Zn(II), and Pb(II) sorption kinetics and equilibrium on hybrid material, composed of pectin and titanium dioxide nanopowder, were examined. Parameters, such as pH and adsorbent dose, were also investigated. The experimental data were better described by the Langmuir model. The maximum adsorption capacities were 1.37, 0.68, 0.51, and 0.83 mmol/g for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The introduction of nano-TiO2 improved the kinetics of the metal ion sorption. The titanium dioxide, despite its small content (6%), contributes to the removal of the examined metal ions and eventually to the adsorption capacity of hybrid beads.

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.