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Volume 13 (2020): Issue 1 (April 2020)

Volume 12 (2019): Issue 2 (October 2019)

Volume 12 (2019): Issue 1 (April 2019)

Volume 11 (2018): Issue 2 (October 2018)

Volume 11 (2018): Issue 1 (April 2018)

Volume 10 (2017): Issue 2 (December 2017)

Volume 10 (2017): Issue 1 (April 2017)

Volume 9 (2016): Issue 2 (October 2016)

Volume 9 (2016): Issue 1 (April 2016)

Volume 8 (2015): Issue 2 (October 2015)

Volume 8 (2015): Issue 1 (April 2015)

Volume 7 (2014): Issue 2 (October 2014)

Volume 7 (2014): Issue 1 (April 2014)

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Volume 6 (2013): Issue 1 (April 2013)

Volume 5 (2012): Issue 2 (October 2012)

Volume 5 (2012): Issue 1 (April 2012)

Journal Details
Format
Journal
eISSN
1339-3065
First Published
10 Dec 2012
Publication timeframe
2 times per year
Languages
English

Search

Volume 10 (2017): Issue 1 (April 2017)

Journal Details
Format
Journal
eISSN
1339-3065
First Published
10 Dec 2012
Publication timeframe
2 times per year
Languages
English

Search

13 Articles
Open Access

Degradation of anti-inflammatory drug diclofenac in sewage water

Published Online: 23 Jun 2017
Page range: 1 - 5

Abstract

Abstract

In recent years, interest in the presence of chemical and biological pollutants (drugs, pesticides, heavy metals etc.) in sewage water has been permanently increasing and, at the same time, significant effort to eliminate them has been shown. The aim of this work was to investigate the influence of ferrates activity on the decomposition of the drug diclofenac (DCF), which is commonly present in sewage water. The main task is to follow the effect of potassium ferrate dosage on DCF degradation and to evaluate the most effective ferrates concentration in solution. Subsequently, real samples of waste water containing a significant amount of various micro‑pollutants were treated by the same amount of ferrates as laboratory samples. High-performance liquid chromatography (HPLC) was used for the sample analysis. Ferrates removal effectiveness was determined by comparing the chromatographic peak areas of residual DCF in the treated samples. Removal efficiency of diclofenac is proportional to the concentration of potassium ferrate in the treated solutions.

Keywords

  • potassium ferrate
  • diclofenac
  • sewage water
Open Access

Molecular orbital analysis of selected organic p-type and n-type conducting small molecules

Published Online: 23 Jun 2017
Page range: 6 - 16

Abstract

Abstract

In this article, the selected series of commercially available p-type and n-type semiconducting small molecules are systematically studied by density functional theory using the B3LYP hybrid functional and 6-311G(2d,p) basis set. The optimal geometries of each molecule in the electronic neutral and corresponding charged states are calculated. The evaluated energies of frontier molecular orbitals and electronic band gaps are mutually compared together with adiabatic electronic intramolecular reorganization energies. The chemical accuracy of the evaluated theoretical quantities is estimated from the comparison with available experimental data.

Keywords

  • Aromatic structure
  • chemical structure
  • electron structure
  • molecular orbital
  • reorganization energy
Open Access

A new catalyst for aldol condensation reactions

Published Online: 23 Jun 2017
Page range: 17 - 20

Abstract

Abstract

A new manganese complex was synthesised incorporating 1,2-diaminobenzene linked ketopinic acid scaffold, and successfully utilised as catalyst in the aldol condensation reactions of benzaldehyde with various aliphatic ketones to obtain products with excellent yield of >99 %.

Keywords

  • Lewis acid
  • manganese
  • 1,2-diaminobenzene
  • catalysis
  • aldol condensation
Open Access

Electrochemical and analytical performance of boron-doped diamond electrode for determination of ascorbic acid

Published Online: 23 Jun 2017
Page range: 21 - 28

Abstract

Abstract

The electrochemical behavior and determination of ascorbic acid (AA) was investigated at a bare boron-doped diamond (BDD) electrode using cyclic and differential pulse voltammetry. The influence of pH of supporting electrolyte and scan rate on the current response of analyte was examined to select the suitable experimental conditions. It was found that AA provided one well-shaped irreversible and diffusioncontrolled oxidation peak at +0.87 V vs. Ag/AgCl in Britton-Robinson buffer pH 4.0. Applying differential pulse voltammetry, the peak current of AA was linearly proportional to its concentration from 5 × 10-6 to 2 × 10-4 mol L-1 (R2 = 0.999), with the limit of detection of 1.1 × 10-6 mol L-1 and the good repeatability (relative standard deviation of 2.3 %). The developed electroanalytical protocol was successfully applied to determine the content of AA in commercial pharmaceutical preparations, based on the standard additions method, with the obtained recovery of 122 %. The accomplished analytical performance indicates that BDD electrodes are promising electrochemical sensors for pharmaceutical analysis.

Keywords

  • ascorbic acid
  • boron-doped diamond
  • differential pulse voltammetry
  • limit of detection
  • pharmaceutical analysis
Open Access

Composition of fatty acids and tocopherols in peels, seeds and leaves of Sea buckthorn

Published Online: 23 Jun 2017
Page range: 29 - 34

Abstract

Abstract

Peels, seeds and leaves of the Sea buckthorn were extracted by methanol and chloroform and characterized in terms of the fatty acids (FA) and tocopherol composition. All morphological parts of Sea buckthorn contained these biologically active compounds useful in medicine, pharmacology, human nutrition and cosmetics. The highest amount of α-tocopherol was found in peels (1103 mg kg-1). The lowest content of α-tocopherol was found in leaves (659 mg kg-1). Delta-tocopherol was found in higher amount in peels 1757 mg kg-1. Seeds contained 95 mg kg-1 of delta-tocopherols. Gamma-tocopherol was found in seeds (459 mg kg-1), peels (188 mg kg-1) and in leaves (587 mg kg-1). β-tocopherol was present only in seeds (171 mg kg-1). Unsaturated fatty acids were dominant in all morphological parts of Sea buckthorn. The highest amounts of unsaturated fatty acids (92 rel. %) were determined in seeds. Dominant fatty acids of seeds were linoleic acid (37 %), α-linolenic acid (30 %) and vaccenic acid (20 %). Leaves were rich in α-linolenic acid (51 %). Dominant fatty acids of peels were oleic acid (16 %), palmitic acid (33 %) and palmitoleic acid (29 %).

Keywords

  • Sea buckthorn
  • extraction
  • fatty acid
  • tocopherol
  • antioxidants
Open Access

Acidic and alkaline bimolecular hydrolysis of substituted formanilides. Computational analysis and modelling of substitution effects

Published Online: 23 Jun 2017
Page range: 35 - 40

Abstract

Abstract

In this article, the study of 67 compounds representing various para-, meta- and ortho- substituted formanilides is presented. These molecules and the products of their acidic and alkaline hydrolysis were studied using DFT quantum chemical methods in order to calculate the reaction enthalpies. These enthalpies are correlated with the hydrolysis rate constants, kH, published for the acid-catalysed acyl cleavage bimolecular (AAC2) mechanism and the modified base-catalysed acyl cleavage bimolecular (BAC2) mechanism. The found linear dependences can be used for the prediction of rate constants of non-synthesised formanilide derivatives.

Keywords

  • Substituent Effect
  • Chemical Kinetics
  • Model Compound
  • Thermodynamic
  • Trans Isomer
  • Cis Isomer
Open Access

MSPD as sample preparation method for determination of selected pesticide residues in apples

Published Online: 23 Jun 2017
Page range: 41 - 46

Abstract

Abstract

A method for extraction and fast gas chromatographic (GC) determination of twenty pesticide residues of different volatility and polarity at ultratrace concentration level in apples is presented. Apples as representatives of non-fatty food were chosen as a matrix; they are also a common raw material for baby food production. Under fast GC conditions employing a mass spectrometric detector (MSD), several parameters of the MSPD procedure were optimised. Samples were homogenised with sorbent Florisil, pesticides were eluted with the optimised volume of etylacetate. After solvent evaporation to dryness, reconstitution of the rest to toluene follow and the final extract was injected. Recoveries obtained at three selected concentration levels were determined. The optimised procedure led to recoveries ≥ 90 % for the majority of the studied pesticides and the limits of quantification (LOQs) < 5 μg.kg-1. Repeatability of gas chromatography-mass spectrometry (GC-MS) measurements of the matrix matched standards, expressed as the relative standard deviation (RSD [%]), was in most cases acceptable for ultratrace concentration levels of pesticide residues.

Keywords

  • Fast GC
  • GC-MS
  • MSPD
Open Access

A new method for macrolide antibiotics determination in wastewater from three different wastewater treatment plants

Published Online: 23 Jun 2017
Page range: 47 - 53

Abstract

Abstract

An effective and practical method for the determination of macrolide antibiotics azithromycin, clarithromycin, erythromycin and roxithromycin in wastewater samples has been developed. The analytical method combines solid phase extraction followed by a chromatographic separation by hydrophilic interaction liquid chromatography (HILIC) coupled with an ion trap mass spectrometer utilizing the electrospray ionization technique. Detection of positively charged ions was performed in full scan mode from 500 to 900 m/z. The method detection limits and method quantification limits obtained were in the range of 2.03-7.59 ng L-1 and 6.08-23.84 ng L-1, respectively. Recoveries of solid phase extraction were obtained using SupelTM-Select HLB cartridges ranging from 85.76 % to 92.54 %. All target antibiotics were detected in 100 % of the collected raw influent samples with concentrations varying from 15 ng L-1 to 1849 ng L-1. Azithromycin, clarithromycin and erythromycin were also detected in 100 % of the treated water samples and roxithromycin was present in 96 % of the samples. The highest determined concentration in the treated water samples was 1404 ng L-1 of azithromycin. Based on the determined macrolide concentrations, removal efficiencies of individual wastewater treatment plants were calculated to range from 13 % to 100 %.

Keywords

  • high-performance liquid chromatography (HPLC)
  • macrolide antibiotics
  • mass spectrometry (MS)
  • solid phase extraction (SPE)
  • wastewater
Open Access

Preliminary evaluation of resorcinol-formaldehyde carbon gels for water pollutants removal

Published Online: 23 Jun 2017
Page range: 54 - 60

Abstract

Abstract

The present work was aimed to evaluate the suitability of resorcinol-formaldehyde carbon gels as adsorbent for water pollutants removal. The carbon gels were characterized using N2 adsorption-desorption isotherm for specific surface area, and Fourier transform infrared (FTIR) for surface functional groups. Methylene blue and cesium were employed as model water pollutants. Results show that the un-oxidized carbon gel, despite its lower specific surface area (333 m2/g) displayed a 118 mg/g removal of methylene blue, that is higher than 35 mg/g by the oxidized carbon gel (418 m2/g). The evaluation of adsorption kinetics revealed a lower pseudo-first order rate constant of 0.088 h-1 for 10 mg/L methylene blue adsorption. A positive effect of surface oxidation was demonstrated for cesium adsorption. On molar basis, however, the oxidized carbon gel exhibits a selective removal towards methylene blue compared to cesium. Carbon gel is a promising candidate for water pollutants removal, and further treatment needs to be sought to boost its performance.

Keywords

  • Adsorption
  • carbon gel
  • cesium
  • methylene blue
  • surface oxidation
Open Access

Sequential determination of 99Tc and 126Sn in radioactive concentrate

Published Online: 23 Jun 2017
Page range: 61 - 64

Abstract

Abstract

This paper describes a new sequential method using anion exchange resin, which is commercially available from Eichrom Technologies, Inc., for the determination of 99Tc and 126Sn in nuclear waste samples. For the determination of non-actinide radionuclides in radioactive wastes, several methods have been recently introduced. This method is suitable for the separation of radionuclides 99Tc and 126Sn from acidic solutions. Samples after digestion were directly loaded in 2 mol·dm-3 HCl acid on a cation exchange resin and then on an anion exchange. They were eluted with HNO3. After elution, the eluted fractions were measured either by gamma spectrometry on an HPGe detector or liquid scintillation counter with high chemical recoveries for a short period of time. Activity concentrations of 126Sn were below minimum detectable activity (MDA) for each experiment. A new radioanalytical method for the sequential determination of 99Tc and 126Sn in radioactive concentrates has been developed and successfully applied. The main advantage of the method was the time required for the separation of radionuclides, which was only five hours, and single column separation for the determination of these radionuclides, which makes the method very effective and cheap.

Keywords

  • anion exchange
  • radioactive concentrate
  • sequential determination
  • Sn-126 separation
  • Tc-99 separation
Open Access

Study of surface-enhanced infrared absorption spectroscopy (SEIRAS) of black inkjet prints using silver colloid

Published Online: 23 Jun 2017
Page range: 65 - 69

Abstract

Abstract

Only black inkjet prints were studied with regard to forensic examination of documents. We analysed twenty-one inkjet prints using surface-enhanced infrared absorption spectroscopy (SEIRAS). The present paper deals with micro-destructive document analysis based on silver nanoparticles (AgNPs) use to obtain surface enhanced ATR-FTIR (attenuated total reflection - Fourier transform infrared) spectra directly from the document. For this experiment, AgNPs in colloid form was applied. AgNPs for SEIRAS analyses were synthesised and afterwards analysed by scanning electron microscopy (SEM). The purpose of the enhancement of colloids was to improve the resolution of the absorption signal of the analysed samples from noise. In the experiment, the obtained ink ATR-FTIR spectra, with and without silver treatment, were significantly affected by the paper base.

Keywords

  • SEIRAS
  • SEM
  • inkjet prints
  • silver colloid
Open Access

Alternative processes of nitrogen removal from wastewater — startup of nitritation reactor

Published Online: 23 Jun 2017
Page range: 70 - 73

Abstract

Abstract

Efficient nitritation was tested in SBR with the aim to accumulate nitrites and to minimize nitrates production in reject wastewater with 500 mg L-1 (NH4++ NH3)-N and with different molar ratios of HCO3-: (NH4++ NH3)-N (1.1-2.1). More than 80 % efficiency of nitritation and permanent inhibition of NOB were achieved at the ratios of 1.71.9 and at the loading of 0.16-0.6 kg (NH4++ NH3)-N m-3 d-1. Under these conditions, the outflow pH was in the range of 5.9-6.5, outflow c (NO2- + HNO2)-N increased up to 400 mg L-1 and c (NO3-)-N dropped below 50 mg L-1. Undissociated HNO2 was confirmed as the main inhibitor of NOB.

Keywords

  • AOB
  • nitritation
  • NOB inhibition
  • sequencing batch reactor
  • sludge reject water
Open Access

Crystal and electronic structure, N–H⋯N and C–H⋯O interactions in novel spiro-[chroman-chromene]-carboxylate

Published Online: 23 Jun 2017
Page range: 74 - 78

Abstract

Abstract

We report here the structure of new spiro-derivative, namely methyl (2R,4R)-4-(5-methylthiazol- 2-ylamino)spiro[chroman-2,2’-chromene]-3’-carboxylate, C23H20N2O4S, which crystallizes as racemate in the space group P-1. In this compound, the chromanone moiety consists of a benzene ring fused with a sixmembered heterocyclic ring which adopts a distorted half-chair conformation. The molecules are linked by a combination of N–H⋯N hydrogen bonds and weak C–H⋯O, C-H⋯S, C-H⋯π, inter- and intramolecular interactions resulting in a two-dimensional network in the crystal structure.

Keywords

  • carboxylates
  • crystal structure
  • spiro chroman-chromene
  • hydrogen bonding
13 Articles
Open Access

Degradation of anti-inflammatory drug diclofenac in sewage water

Published Online: 23 Jun 2017
Page range: 1 - 5

Abstract

Abstract

In recent years, interest in the presence of chemical and biological pollutants (drugs, pesticides, heavy metals etc.) in sewage water has been permanently increasing and, at the same time, significant effort to eliminate them has been shown. The aim of this work was to investigate the influence of ferrates activity on the decomposition of the drug diclofenac (DCF), which is commonly present in sewage water. The main task is to follow the effect of potassium ferrate dosage on DCF degradation and to evaluate the most effective ferrates concentration in solution. Subsequently, real samples of waste water containing a significant amount of various micro‑pollutants were treated by the same amount of ferrates as laboratory samples. High-performance liquid chromatography (HPLC) was used for the sample analysis. Ferrates removal effectiveness was determined by comparing the chromatographic peak areas of residual DCF in the treated samples. Removal efficiency of diclofenac is proportional to the concentration of potassium ferrate in the treated solutions.

Keywords

  • potassium ferrate
  • diclofenac
  • sewage water
Open Access

Molecular orbital analysis of selected organic p-type and n-type conducting small molecules

Published Online: 23 Jun 2017
Page range: 6 - 16

Abstract

Abstract

In this article, the selected series of commercially available p-type and n-type semiconducting small molecules are systematically studied by density functional theory using the B3LYP hybrid functional and 6-311G(2d,p) basis set. The optimal geometries of each molecule in the electronic neutral and corresponding charged states are calculated. The evaluated energies of frontier molecular orbitals and electronic band gaps are mutually compared together with adiabatic electronic intramolecular reorganization energies. The chemical accuracy of the evaluated theoretical quantities is estimated from the comparison with available experimental data.

Keywords

  • Aromatic structure
  • chemical structure
  • electron structure
  • molecular orbital
  • reorganization energy
Open Access

A new catalyst for aldol condensation reactions

Published Online: 23 Jun 2017
Page range: 17 - 20

Abstract

Abstract

A new manganese complex was synthesised incorporating 1,2-diaminobenzene linked ketopinic acid scaffold, and successfully utilised as catalyst in the aldol condensation reactions of benzaldehyde with various aliphatic ketones to obtain products with excellent yield of >99 %.

Keywords

  • Lewis acid
  • manganese
  • 1,2-diaminobenzene
  • catalysis
  • aldol condensation
Open Access

Electrochemical and analytical performance of boron-doped diamond electrode for determination of ascorbic acid

Published Online: 23 Jun 2017
Page range: 21 - 28

Abstract

Abstract

The electrochemical behavior and determination of ascorbic acid (AA) was investigated at a bare boron-doped diamond (BDD) electrode using cyclic and differential pulse voltammetry. The influence of pH of supporting electrolyte and scan rate on the current response of analyte was examined to select the suitable experimental conditions. It was found that AA provided one well-shaped irreversible and diffusioncontrolled oxidation peak at +0.87 V vs. Ag/AgCl in Britton-Robinson buffer pH 4.0. Applying differential pulse voltammetry, the peak current of AA was linearly proportional to its concentration from 5 × 10-6 to 2 × 10-4 mol L-1 (R2 = 0.999), with the limit of detection of 1.1 × 10-6 mol L-1 and the good repeatability (relative standard deviation of 2.3 %). The developed electroanalytical protocol was successfully applied to determine the content of AA in commercial pharmaceutical preparations, based on the standard additions method, with the obtained recovery of 122 %. The accomplished analytical performance indicates that BDD electrodes are promising electrochemical sensors for pharmaceutical analysis.

Keywords

  • ascorbic acid
  • boron-doped diamond
  • differential pulse voltammetry
  • limit of detection
  • pharmaceutical analysis
Open Access

Composition of fatty acids and tocopherols in peels, seeds and leaves of Sea buckthorn

Published Online: 23 Jun 2017
Page range: 29 - 34

Abstract

Abstract

Peels, seeds and leaves of the Sea buckthorn were extracted by methanol and chloroform and characterized in terms of the fatty acids (FA) and tocopherol composition. All morphological parts of Sea buckthorn contained these biologically active compounds useful in medicine, pharmacology, human nutrition and cosmetics. The highest amount of α-tocopherol was found in peels (1103 mg kg-1). The lowest content of α-tocopherol was found in leaves (659 mg kg-1). Delta-tocopherol was found in higher amount in peels 1757 mg kg-1. Seeds contained 95 mg kg-1 of delta-tocopherols. Gamma-tocopherol was found in seeds (459 mg kg-1), peels (188 mg kg-1) and in leaves (587 mg kg-1). β-tocopherol was present only in seeds (171 mg kg-1). Unsaturated fatty acids were dominant in all morphological parts of Sea buckthorn. The highest amounts of unsaturated fatty acids (92 rel. %) were determined in seeds. Dominant fatty acids of seeds were linoleic acid (37 %), α-linolenic acid (30 %) and vaccenic acid (20 %). Leaves were rich in α-linolenic acid (51 %). Dominant fatty acids of peels were oleic acid (16 %), palmitic acid (33 %) and palmitoleic acid (29 %).

Keywords

  • Sea buckthorn
  • extraction
  • fatty acid
  • tocopherol
  • antioxidants
Open Access

Acidic and alkaline bimolecular hydrolysis of substituted formanilides. Computational analysis and modelling of substitution effects

Published Online: 23 Jun 2017
Page range: 35 - 40

Abstract

Abstract

In this article, the study of 67 compounds representing various para-, meta- and ortho- substituted formanilides is presented. These molecules and the products of their acidic and alkaline hydrolysis were studied using DFT quantum chemical methods in order to calculate the reaction enthalpies. These enthalpies are correlated with the hydrolysis rate constants, kH, published for the acid-catalysed acyl cleavage bimolecular (AAC2) mechanism and the modified base-catalysed acyl cleavage bimolecular (BAC2) mechanism. The found linear dependences can be used for the prediction of rate constants of non-synthesised formanilide derivatives.

Keywords

  • Substituent Effect
  • Chemical Kinetics
  • Model Compound
  • Thermodynamic
  • Trans Isomer
  • Cis Isomer
Open Access

MSPD as sample preparation method for determination of selected pesticide residues in apples

Published Online: 23 Jun 2017
Page range: 41 - 46

Abstract

Abstract

A method for extraction and fast gas chromatographic (GC) determination of twenty pesticide residues of different volatility and polarity at ultratrace concentration level in apples is presented. Apples as representatives of non-fatty food were chosen as a matrix; they are also a common raw material for baby food production. Under fast GC conditions employing a mass spectrometric detector (MSD), several parameters of the MSPD procedure were optimised. Samples were homogenised with sorbent Florisil, pesticides were eluted with the optimised volume of etylacetate. After solvent evaporation to dryness, reconstitution of the rest to toluene follow and the final extract was injected. Recoveries obtained at three selected concentration levels were determined. The optimised procedure led to recoveries ≥ 90 % for the majority of the studied pesticides and the limits of quantification (LOQs) < 5 μg.kg-1. Repeatability of gas chromatography-mass spectrometry (GC-MS) measurements of the matrix matched standards, expressed as the relative standard deviation (RSD [%]), was in most cases acceptable for ultratrace concentration levels of pesticide residues.

Keywords

  • Fast GC
  • GC-MS
  • MSPD
Open Access

A new method for macrolide antibiotics determination in wastewater from three different wastewater treatment plants

Published Online: 23 Jun 2017
Page range: 47 - 53

Abstract

Abstract

An effective and practical method for the determination of macrolide antibiotics azithromycin, clarithromycin, erythromycin and roxithromycin in wastewater samples has been developed. The analytical method combines solid phase extraction followed by a chromatographic separation by hydrophilic interaction liquid chromatography (HILIC) coupled with an ion trap mass spectrometer utilizing the electrospray ionization technique. Detection of positively charged ions was performed in full scan mode from 500 to 900 m/z. The method detection limits and method quantification limits obtained were in the range of 2.03-7.59 ng L-1 and 6.08-23.84 ng L-1, respectively. Recoveries of solid phase extraction were obtained using SupelTM-Select HLB cartridges ranging from 85.76 % to 92.54 %. All target antibiotics were detected in 100 % of the collected raw influent samples with concentrations varying from 15 ng L-1 to 1849 ng L-1. Azithromycin, clarithromycin and erythromycin were also detected in 100 % of the treated water samples and roxithromycin was present in 96 % of the samples. The highest determined concentration in the treated water samples was 1404 ng L-1 of azithromycin. Based on the determined macrolide concentrations, removal efficiencies of individual wastewater treatment plants were calculated to range from 13 % to 100 %.

Keywords

  • high-performance liquid chromatography (HPLC)
  • macrolide antibiotics
  • mass spectrometry (MS)
  • solid phase extraction (SPE)
  • wastewater
Open Access

Preliminary evaluation of resorcinol-formaldehyde carbon gels for water pollutants removal

Published Online: 23 Jun 2017
Page range: 54 - 60

Abstract

Abstract

The present work was aimed to evaluate the suitability of resorcinol-formaldehyde carbon gels as adsorbent for water pollutants removal. The carbon gels were characterized using N2 adsorption-desorption isotherm for specific surface area, and Fourier transform infrared (FTIR) for surface functional groups. Methylene blue and cesium were employed as model water pollutants. Results show that the un-oxidized carbon gel, despite its lower specific surface area (333 m2/g) displayed a 118 mg/g removal of methylene blue, that is higher than 35 mg/g by the oxidized carbon gel (418 m2/g). The evaluation of adsorption kinetics revealed a lower pseudo-first order rate constant of 0.088 h-1 for 10 mg/L methylene blue adsorption. A positive effect of surface oxidation was demonstrated for cesium adsorption. On molar basis, however, the oxidized carbon gel exhibits a selective removal towards methylene blue compared to cesium. Carbon gel is a promising candidate for water pollutants removal, and further treatment needs to be sought to boost its performance.

Keywords

  • Adsorption
  • carbon gel
  • cesium
  • methylene blue
  • surface oxidation
Open Access

Sequential determination of 99Tc and 126Sn in radioactive concentrate

Published Online: 23 Jun 2017
Page range: 61 - 64

Abstract

Abstract

This paper describes a new sequential method using anion exchange resin, which is commercially available from Eichrom Technologies, Inc., for the determination of 99Tc and 126Sn in nuclear waste samples. For the determination of non-actinide radionuclides in radioactive wastes, several methods have been recently introduced. This method is suitable for the separation of radionuclides 99Tc and 126Sn from acidic solutions. Samples after digestion were directly loaded in 2 mol·dm-3 HCl acid on a cation exchange resin and then on an anion exchange. They were eluted with HNO3. After elution, the eluted fractions were measured either by gamma spectrometry on an HPGe detector or liquid scintillation counter with high chemical recoveries for a short period of time. Activity concentrations of 126Sn were below minimum detectable activity (MDA) for each experiment. A new radioanalytical method for the sequential determination of 99Tc and 126Sn in radioactive concentrates has been developed and successfully applied. The main advantage of the method was the time required for the separation of radionuclides, which was only five hours, and single column separation for the determination of these radionuclides, which makes the method very effective and cheap.

Keywords

  • anion exchange
  • radioactive concentrate
  • sequential determination
  • Sn-126 separation
  • Tc-99 separation
Open Access

Study of surface-enhanced infrared absorption spectroscopy (SEIRAS) of black inkjet prints using silver colloid

Published Online: 23 Jun 2017
Page range: 65 - 69

Abstract

Abstract

Only black inkjet prints were studied with regard to forensic examination of documents. We analysed twenty-one inkjet prints using surface-enhanced infrared absorption spectroscopy (SEIRAS). The present paper deals with micro-destructive document analysis based on silver nanoparticles (AgNPs) use to obtain surface enhanced ATR-FTIR (attenuated total reflection - Fourier transform infrared) spectra directly from the document. For this experiment, AgNPs in colloid form was applied. AgNPs for SEIRAS analyses were synthesised and afterwards analysed by scanning electron microscopy (SEM). The purpose of the enhancement of colloids was to improve the resolution of the absorption signal of the analysed samples from noise. In the experiment, the obtained ink ATR-FTIR spectra, with and without silver treatment, were significantly affected by the paper base.

Keywords

  • SEIRAS
  • SEM
  • inkjet prints
  • silver colloid
Open Access

Alternative processes of nitrogen removal from wastewater — startup of nitritation reactor

Published Online: 23 Jun 2017
Page range: 70 - 73

Abstract

Abstract

Efficient nitritation was tested in SBR with the aim to accumulate nitrites and to minimize nitrates production in reject wastewater with 500 mg L-1 (NH4++ NH3)-N and with different molar ratios of HCO3-: (NH4++ NH3)-N (1.1-2.1). More than 80 % efficiency of nitritation and permanent inhibition of NOB were achieved at the ratios of 1.71.9 and at the loading of 0.16-0.6 kg (NH4++ NH3)-N m-3 d-1. Under these conditions, the outflow pH was in the range of 5.9-6.5, outflow c (NO2- + HNO2)-N increased up to 400 mg L-1 and c (NO3-)-N dropped below 50 mg L-1. Undissociated HNO2 was confirmed as the main inhibitor of NOB.

Keywords

  • AOB
  • nitritation
  • NOB inhibition
  • sequencing batch reactor
  • sludge reject water
Open Access

Crystal and electronic structure, N–H⋯N and C–H⋯O interactions in novel spiro-[chroman-chromene]-carboxylate

Published Online: 23 Jun 2017
Page range: 74 - 78

Abstract

Abstract

We report here the structure of new spiro-derivative, namely methyl (2R,4R)-4-(5-methylthiazol- 2-ylamino)spiro[chroman-2,2’-chromene]-3’-carboxylate, C23H20N2O4S, which crystallizes as racemate in the space group P-1. In this compound, the chromanone moiety consists of a benzene ring fused with a sixmembered heterocyclic ring which adopts a distorted half-chair conformation. The molecules are linked by a combination of N–H⋯N hydrogen bonds and weak C–H⋯O, C-H⋯S, C-H⋯π, inter- and intramolecular interactions resulting in a two-dimensional network in the crystal structure.

Keywords

  • carboxylates
  • crystal structure
  • spiro chroman-chromene
  • hydrogen bonding

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