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Photocatalytic activity of NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by Eu(III) and Tb(III) for decomposition of Malachite Green

  • M. P. Tsvetkov EMAIL logo , I. R. Ivanova , E. P. Valcheva , J. Ts. Zaharieva and M. M. Milanova
Published/Copyright: December 18, 2019
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Open Chemistry
From the journal Open Chemistry Volume 17 Issue 1

Abstract

The mixed metal oxides NiFe2O4 and Zn0.5Ni0.5Fe2O4 with a spinel-like structure, pure and modified with the lanthanide ions Eu(III) and Tb(III), were prepared by a sol-gel process in which propylene oxide was used as a gelling agent and then tested as photocatalysts. The photocatalytic activity was studied under polychromic visible light irradiation (halogen lamp) for the decomposition of the water pollutant Malachite Green in model solutions which were prepared under laboratory conditions. The modified samples showed a better activity under visible light irradiation than the pure samples. The highest activity under visible light irradiation was observed for Zn0.5Ni0.5Fe2O4 that was modified with 5 wt. % Eu(III) or Tb(III), and which showed the positive effects of the doping ions. Based on the cartographic data for the smooth and equal distribution of Tb(III) on the surface of Zn0.5Ni0.5Fe2O4 particles, the surface processes may have influenced the photocatalytic activity. The energy band gap of the samples was calculated, showing somewhat lower values for the doped samples than the pure ferrites.

Keywords: ferrites; lanthanide ions; photocatalytic activity; rate constants; band gap energy

1 Introduction

Mixed metal oxides with a spinel-like structure can be presented with the formula M’M’’2O4, where M’ represents a divalent metal ion and M’’ represents a trivalent metal ion such as Al, Cr, Fe, etc.; if M’’ is Fe(III) these metal oxides are also called ferrites. They are technologically important systems and have been used in many applications including magnetic recording media for the storage and/or retrieval of information, magnetic fluids, magnetic resonance imaging enhancement, catalysis, magnetically guided drug delivery, sensors, pigments, etc. [1, 2, 3]. Recent investigations focus on their photocatalytic properties to elucidate their application for the degradation of water pollutants, as reviewed in [4]. Of special interest are both their ability to catalyze the photodegradation of water pollutants in visible light and their magnetic properties, which make it easy to separate the catalyst from the purified water after use. It has been found that some properties of these mixed metal oxides with a spinel-like structure can be influenced by modifying the lanthanide ions Ln(III) [5, 6, 7, 8, 9, 10, 11, 12, 13, 14]. We therefore think it is worth investigating what influence some Ln(III) have on the photocatalytic activity of ferrites. There is limited information for the photocatalytic degradation of Malachite Green (MG) by ferrites. In our laboratory mixed metal oxides with a spinel-like structure were synthesized by mechanotreatment, both of the type MFe2O4, where M = Zn, Ni or Co, and of the type M’M’’Fe2O4, where M’=Zn and M’’ = Ni or Co; these samples were tested for the degradation of MG under UV irradiation [15]. Because of NiFe2O4 and Zn0.5Ni0.5Fe2O4 showing especially promising behavior as photocatalysts, they were selected for the modification with lanthanide ions such as Eu(III) or Tb(III). The synthesized and characterized NiFe2O4 and Zn0.5Ni0.5Fe2O4 doped with Eu(III) or Tb(III) are presented in [16]. The X-ray diffraction and Mossbauer spectroscopy proved that the samples were monophasic ferrites. It was shown that Ln(III) ions affected the magnetic properties

of ferrites, however, their influence was indirect and only due to their effect on the average particle size. The results of the investigation on the photocatalytic activity of these samples are discussed in this work.

2 Experimental and methods

The synthesis by the applied sol-gel method and the characterization of the samples NiFe2O4 and Zn0.5Ni0.5Fe2O4 by XRD and Mossbauer and Raman spectroscopy and those samples modified with Ln(III) ions (Ln = Eu or Tb) are presented in detail in [16]. The samples were prepared by mixing the solutions of the nitrates in 96% ethanol, and then stirring the solutions for complete homogenization; propylene oxide was added in a molar ratio of 1:4 to the ethanol, then the solutions were continually stirred until a sol was formed. The sol was dried for 48h at 60oC and annealed for 5h at 550oC. Propylene oxide was used to make hydroxyl groups on the hydrated cations and to induce a polycondensation reaction between the ions of Fe3+, Ni2+ and Zn2+. The gel formation was almost immediate while other gelling agents took much longer to form a gel. In the text below the powdered samples tested as photocatalysts are referred to as NF-Ln1, NF-Ln5 and ZNF-Ln1, ZNF-Ln5 (Ln = Eu or Tb), where NF or ZNF refers to the mixed metal oxides NiFe2O4 or Zn0.5Ni0.5Fe2O4, and the symbol of the Ln(III) ion is followed by its content (1 or 5 wt. %). In total, 10 samples (2 unmodified and 8 modified) were tested as photocatalysts, and the results are discussed below.

For the purpose of the photocatalytic data interpretation, additional characterizations were done by the methods presented in this section.

Specific surface area, SSA, was determined using nitrogen at 77K by the Brunauer–Emmett–Teller (BET) method.

UV-Vis absorption spectra were recorded in the range 200-900 nm using an Evolution 300 UV-Vis spectrometer (Thermo Scientific).

TEM, transmission electron microscopy, investigations were performed on a JEOL 2100 transmission electron microscope.

Band gap energy calculations. The optical properties (absorption and optical band gap energy) of the samples were studied using UV-Vis spectroscopy. In all cases, broad absorption was observed in the 300–900 nm range of the spectra. The UV–Vis data were analyzed to determine the relationship between the optical band gap, absorption coefficient and energy (hν) of the incident photon for near edge optical absorption in semiconductors. The band gap energy was calculated from the measured curves according to Tauc’s equation [17] αhν = A(hν − Eg)n, where A is a constant independent of hν, Eg is the semiconductor band gap and n depends on the type of transition. In addition, the well-known approach to determine the semiconductor band gap energy from the intersection of linear fits of (αhν)1/n versus hv on the x-axis was used, n being 1/2 and 2 for direct and indirect band gap, respectively.

The photocatalytic tests were performed in a slurry (1 g catalyst L-1), using a 10-5 M aqueous solution of Malachite Green oxalate (MG), (Chroma GmbH) as a model pollutant. The equipment and the procedure used were the same ones as for the photocatalytic measurements published in [15, 15, 18, 19, 20]. After a 60-min ‘‘dark’’ period (to establish the equilibrium of the sorption process), the system was illuminated by a halogen lamp (Kanlux S.А., J-300W 118 MM, correlated color temperature 2710 K, 300 W, polychromatic, 300 - 800 nm, maximum at 600 nm), situated at 20 cm distance above the slurry, under continuous magnetically stirring (400 min-1) and bubbling with air (45 L h-1). The initial pH of the solutions was between 5.8 and 5.9. Periodically, a 5 mL aliquot was taken from the solution and filtered through a 0.20 μm Minisart filter. The dye concentration was determined spectrophotometrically by the band at 620 nm. The data obtained were plotted in coordinates (C/C0)/t and -ln(C/ C0)/t (where C0 is the concentration after the ‘‘dark’’ period, and C is the concentration after t min irradiation), and apparent rate constants of the degradation process were determined assuming first-order kinetics. The sorption capacity was calculated as the ratio (C00–C0)/C00, where C00 is the starting solution concentration (before the ‘‘dark’’ period). The MG degradation at moment t is determined by the formula: degradation, % = (Ао – Аt)/Ао х 100, where Ао is the initial absorption of the MG solution at t = 0 min, and Аt is the absorption at t min. The duration of visible irradiation was 150 min. The experiments were repeated in triplicate.

The pH value of the solution was found to be 5.8 in the beginning and 6.5 at the end of the test. The measurements of the ion concentrations in the filtrates made by atomic absorption spectroscopy showed a very low value for Zn(II), namely 3.10-6 g/L, while Ni(II) and Fe(II) ions were not detected, obviously due to their concentrations under the detection limit of the applied method. These data show the stability of the catalysts in the pH interval 5.8-6.5 of the photocatalytic test.

Ethical approval: The conducted research is not related to either human or animal use.

3 Results and discussion

3.1 Characterization of the samples

3.1.1 Average crystallite size and specific surface area (SSA)

The modified samples showed well-crystallized particles with size in the range of 9-18 nm (Table 1). The average crystallite size for the NF-Ln samples was observed to decrease with increasing Ln(III) content, while the size of the ZNF-Ln crystallites also decreased but to a lesser extent (Table 1). The low value for SSA for the pure NF and ZNF samples correlated well with their larger crystallite size of 18 nm (Table 1). The average crystallite size determined from XRD data (using Scherrer equation, about 15 nm, Table 1) and the evaluated particle size (between 15-20 nm) from the TEM micrographs can be seen in Figure 1 aligned well. TEM micrographs for ZNF-Eu1 (Figure 1, a) and for ZNF-Tb5 (Figure 1, b) are examples shown below. As the particles were closely packed, a particle size distribution analysis could not be made from these images.

Figure 1 TEM micrographs of ZNF-Eu1 (a) and ZNF-Tb5 (b).
Figure 1

TEM micrographs of ZNF-Eu1 (a) and ZNF-Tb5 (b).

Table 1

Specific surface area (SSA) and average crystallite size of the samples.

SampleSSA, m2/gAverage crystallite size, nm [16]*SampleSSA, m2/gAverage crystallite size, nm [16]*
NF3618ZNF3218
NF-Eu14214ZNF-Eu14216
NF-Tb1569ZNF-Tb14215
NF-Eu57913ZNF-Eu55016
NF-Tb5779ZNF-Tb55015

  1. *Values determined by the Scherrer equation; rounded up [16].

The undoped samples NF and ZNF have fairly close values for their specific surface area (SSA), 36 and 32 m2/g, respectively and are the lowest among the investigated samples (Table 1).

The values for SSA for the modified samples NF-Ln and ZNF-Ln (Table 1) were found to be higher compared to the pure undoped NF and ZNF samples, as they increased with an increasing amount of dopant. It is known [21] that La2О3 is one of the best additives for inhibiting the sintering of high surface area gamma-Al2O3, which also has a spinel-like structure. The dopant is believed to decrease the rate of surface diffusion, which delays sintering and a loss of surface area. The effect of the dopant increased with the amount of Ln2O3 [21]. The research conducted for this paper showed similar trends: the values for SSA for the doped samples were higher than those for the unmodified samples; and those samples containing 5 wt. % of dopant showed higher SSA than those containing 1 wt. %, both for the NF-Ln and ZNF-Ln samples. The nature of the dopant (Eu or Tb) appears to be insignificant, with only NF-Tb1 showing a higher SSA than NF-Eu1.

3.1.2 Data from the energy dispersive X-ray microanalysis

The ТЕМ micrographs of the obtained samples were used to make an energy dispersive X-ray microanalysis in several points which were pointed out using digits on the micrographs (Figures 2 a, b, c). The content (wt. %) of Eu(III) in ZNF-Eu1, 1.0 ± 0.1, as well as of Tb(III) in ZNF-Tb1, 4.0 ± 0.6, and in ZNF-Tb5, 7.8 ±1.4 was determined. The value obtained for Eu(III) was very close to the experimental stoichiometric value (1 wt. %). Eu(III) appear to be distributed equally on the particles’ surface, as shown by the elemental mapping (Figure 3). The higher value for Tb(III) both in ZNF-Tb1 and in ZNF-Tb5 suggests Tb(III) enrichment of the surface; the distribution appears to be homogeneous (Figure 4).

Figure 2 ТЕМ – micrographs for ZNF-Eu1, scale bar 500 nm (а), ZNF-Tb1, scale bar 500 nm (b), and ZNF-Tb5 scale bar 100 nm (c); based on them an energy dispersive X-ray microanalysis was made.
Figure 2

ТЕМ – micrographs for ZNF-Eu1, scale bar 500 nm (а), ZNF-Tb1, scale bar 500 nm (b), and ZNF-Tb5 scale bar 100 nm (c); based on them an energy dispersive X-ray microanalysis was made.

Figure 3 Elemental mapping of the sample ZNF-Eu1 (a). The equal distribution of Eu(III) on the surface is shown (b) and for comparison, the distribution of Fe(III) (c).
Figure 3

Elemental mapping of the sample ZNF-Eu1 (a). The equal distribution of Eu(III) on the surface is shown (b) and for comparison, the distribution of Fe(III) (c).

Figure 4 Elemental mapping of the sample ZNF-Tb5 (a). The equal distribution of Tb(III) on the surface is shown (b) and for comparison, the distribution of Fe(III) (c).
Figure 4

Elemental mapping of the sample ZNF-Tb5 (a). The equal distribution of Tb(III) on the surface is shown (b) and for comparison, the distribution of Fe(III) (c).

3.1.3 Energy of the band gap, Eg

The absorbance in the UV/Vis range (450–700 nm, spectra not included here) showed a clear maximum at around 400 nm. Based on these data, the band gap energy, Eg, was determined after plotting α/E, where α is the absorption coefficient. The energy of the band gap of the samples characterized is in the range 1.57 – 1.61 eV (785 – 767 nm); a value of 1.57 eV (785 nm) was calculated for the pure NF and ZNF. These data are somewhat lower than those published in the literature for pure ferrites (1.9 eV for ZnFe2O4 [22, 23] and 2.19 eV for NiFe2O4 [24]), quite likely due to the difference in the synthetic procedure applied. The values calculated for Eu(III) doped (1.57-1.60 eV) as well as for Tb(III) doped (1.58 – 1.61 eV) NF-Ln and ZNF-Ln are close, and apparently do not correlate to the amount of Ln(III) added. Considering the synthetic procedure, it can be expected that the Ln(III) are present as oxides in the samples. In our former work, based on XRD and Mossbauer spectroscopy data, we deduced that Ln3+ most likely formed a second phase; however, due to their low amount, it was not directly observed in the diffractograms [16]. In the literature the calculated and experimental band gaps for the respective oxides show values in the range of 2.25 – 4.4 eV for Eu2O3 (i.e. 550 – 280 nm) and 3.7 - 4.4 eV for Tb2O3 (i.e. 334 – 280 nm) [25]. These values are higher than those calculated for our samples where the Eg values for the doped NF-Ln and ZNF-Ln approximate the value of the pure NF and ZNF.

3.2 Photocatalytic activity of the samples

The results for the photodegradation of Malachite Green (MG) under visible light irradiation in the presence of the synthesized photocatalysts are shown in Figure 5, where the C/C0 dependence on the irradiation time is presented.

Figure 5 Degradation curves (C/C0 dependence on the irradiation time) under visible light irradiation for pure and doped NF (a) and ZNF samples (b).
Figure 5

Degradation curves (C/C0 dependence on the irradiation time) under visible light irradiation for pure and doped NF (a) and ZNF samples (b).

The data for the rate constants of the photocatalytic process along with the sorption of the photocatalysts are summarized in Table 2 and are illustrated additionally in histograms in Figure S1 (Supplementary material).

Table 2

Photocatalytic activity of NF and ZNF, pure and modified with Eu(III) and Tb(III) ions, under irradiation with visible light.

SampleRate constant
n.10-3 min-1to SSA, n.10-4 min-1. g. m-2Degradation after 150 min, %Sorption, %
NF3.43±0.420.95±0.13862.40
NF-Eu13.30±0.060.79±0.013764.11
NF-Tb13.40±0.380.61±0.073858.86
NF-Eu53.50±0.450.44±0.053863.15
NF-Tb54.10±0.380.53±0.054366.53
ZNF5.47±0.381.71±0.125258.30
ZNF-Eu15.0±0.21.19±0.044865.63
ZNF-Tb13.80±0.230.90±0.054063.32
ZNF-Eu56.0±0.61.20±0.126074.91
ZNF-Tb56.77±0.201.35±0.046476.75

The degradation rate constants are divided by the SSA (rate constant/SSA) (an approach applied by us in [20]) and the ‘‘normalized’’ values (min-1 g. m-2) are shown in Table 2. They can be compared with the ‘‘normalized’’ value for the well-known photocatalyst TiO2 Degussa P25, 2.2 x 10-4 min-1 g. m-2, [20] (data obtained for TiO2 Degussa P-25 decomposing Malachite Green with UV light irradiation, rate constant 11.6 x 10-3 min-1, with specific surface area 52 m2/g [20].) Figure 5 shows that after about 80 minutes of irradiation with visible light, a very similar degradation of the dye MG for the different catalysts is achieved. The photocatalysts show differences in their activity in the interval of 80-150 minutes. It is assumed that some deactivation of the catalyst surface took place, which could be proved after a second catalytic cycle test.

Based on the data in Table 2, some tendencies are mentioned in the discussion below.

3.2.1 Pure vs. doped ferrites and the content of the modifying ions

Comparing the pure undoped samples, ZNF appears to have a higher activity than NF, which must be due to the beneficial effects of adding Zn(II). Doping NF with Ln(III) does not seem to have a significant effect: the rate constants are the same within experimental error, except for that of NF-Tb5, which is slightly higher. The tendency for increasing the rate constants of the photocatalysts in the presence of modifying agents is more obvious for the ZNF-Ln modified samples. The samples containing 1 wt. % Ln are somewhat less active than the unmodified ZNF, especially for the Tb-doped sample, while the samples containing 5 wt. % Ln are more active than the unmodified sample, also especially for the Tb-doped sample. The most active samples are ZNF-Tb5 and ZNF-Eu5 with rate constants of (6.77±0.20) x10-3 min-1 and (6.0±0.6) x10-3 min-1, respectively. They have neither the highest SSA nor the smallest average crystallite size. This fact confirms the statement [26, 27] that the characteristics and peculiarities of the surface structure can be responsible for the differences in the catalytic action, but the process of photodegradation is determined by additional factors. The size of the particles and crystallites may also affect the activity of the photocatalysts by influencing the processes of recombination of the electron-hole pairs, e-/h+.

The increased activity of the modified ZNF with 5 wt. % Ln(III) under visible light irradiation corresponds to the element mapping data for homogeneous distribution of Tb on the surface of ZNF-Tb5 particles and to the enrichment with Tb. In this case there appears to be an influence of the surface processes on the activity.

3.2.2 The influence of the specific surface area and average crystallite size

It can be expected that the specific surface area is important for the photocatalytic process. The samples ZNF-Tb5 and ZNF-Eu5 demonstrate lower SSA compared with the values for NF-Tb5 and NF-Eu5 (50, and 77 and 79 m2/g, respectively) (Table 1). At the same time the higher SSA for NF-Tb5 and NF-Eu5 do not result in higher rate constants. The decrease of the average crystallite size is observed to a different extent for the modified NF-Ln and ZNF-Ln (Table 1). The rate constants of both NF-Ln and ZNF-Ln change in a similar way i.e. they show higher values in comparison with the pure samples. Data published for photocatalytic MG degradation by ferrites is rather limited. Additionally, the comparison is difficult because the photocatalysts tested are synthesized by different synthetic procedures [15, 18, 19].

3.2.3 The band gap energy as a factor in the photocatalytic process

According to [4], to absorb visible light energy, a photocatalyst with a maximum band gap of about 3.1 eV is required. It is known that spinel ferrites have a band gap of approximately 2.0 eV, so they should be capable of photocatalytic conversion of visible light energy to generate electron/hole pairs that in turn produce reactive oxygen species through redox processes for the degradation of pollutants [4]. The data for Eg obtained for our samples (see 3.1.3.) show that they may be applied for photodegradation under visible light, which is proved by the results in Table 2.

3.2.4 Comparing the influence of Eu(III) and Tb(III)

Considering the role of Eu(III) and Tb(III), the content of Ln(III) in the ferrite (1 or 5 wt. %) and the type of ferrite modified (NF or ZNF) have to be taken into account. Based on the role of Ln(III) on the photocatalytic activity of semiconductors such as TiO2 [28], it can be expected that both Eu(III) and Tb(III) adsorbed as oxides on the surface of the spinel favor the separation of the charge carriers, and by that they suppress the recombination of electron/hole pairs and increase the activity of the doped photocatalysts. The powder XRD analysis of the samples [16] showed single-phase ferrites. No additional peaks corresponding to Ln(III) oxides were observed, which would be the case if we indeed had composite material (especially for the samples containing 5 wt % of Eu and Tb). This suggests that the Tb and Eu ions dissolve into the ferrite matrix and are with all likelihood present in the interlayer space of the ferrite. Their influence can be connected with the smaller crystallites size of 10-15 nm (Table 1), which is in agreement with the statement [29] that an average crystallite size of 20 nm is optimal for a high quantum yield. The values for the energy of the band gap Eg are very close to the doped samples NF-Ln and ZNF-Ln; a difference of 0.03 eV is not expected to be significant. The data from Table 2 show that the Tb(III) doped samples have higher rate constants than Eu(III). The only deviation from this trend is ZNF-Tb1, showing lower activity than ZNF-Eu1. Actually, the rate constant of ZNF-Tb1 under visible light has the lowest value among the ZNF-Ln doped samples. The SSA of Tb(III) doped samples is equal or slightly larger than the values of the Eu(III) doped samples. In this case, the SSA as a factor in influencing the photocatalytic activity, acts in synergy with the smaller radius of Tb(III). Generally, the influence of Ln(III) on the photocatalytic activity of ferrites needs further elucidation. The role is likely to be similar on the influence of Ln(III) on the reactivity of TiO2 (investigated photocatalyst, active only under UV light when not modified) i.e. the complexation capability of Ln(III) gives a chance for better adsorption of the pollutants on the surface of the photocatalyst [30]. Considering the smaller radius of Tb(III), it has a better complexation ability than Eu(III), which may be a factor for the better activity of ZNF-Tb5 over ZNF-Eu5.

Taking into account that (i) Ln(III) ions do not enter the lattice cell [16, 31], but quite likely remain on the surface and (ii) the data from the energy dispersive X-ray microanalysis show that they are equally spread on the surface and (iii) the surface is enriched in Tb (III), it is likely that surface processes are essential for the catalytic activity of the ferrites modified with Ln(III). Tb(III) is a unique lanthanoid that has been reported to form mixed valence compounds with a nonstoichiometric structure [32], so there might be a process where Tb(III) disturbs the e-/h+ recombination by its variable oxidation state Tb(III) - Tb(IV).

3.2.5 Comparing NF vs ZNF

Under visible light irradiation, the pure ZNF shows a higher rate constant than the pure NF (Table 2). At the same time, the pure photocatalysts NF and ZNF have close values both for the average crystallite size and for the specific surface area (36 and 32 m2 g-1 respectively, Table 1), equal values for the energy of the band gap according to our calculations (1.57 eV) as well as close values according the literature data (2.19 and 1.9 eV [22, 23, 24]). This means that these factors are not the only ones responsible for the difference in the photocatalytical activity of NF and ZNF.

Among the modified samples, NF-Ln samples generally have lower activity than ZNF-Ln modified samples; among all the samples tested the lowest rate constant was found for NF-Eu1, i.e. 3.3 x 10-3 min-1. The rate constants for ZNF-Ln5 are almost twice as large as those for NF-Ln5. ZNF doped with 5 wt. % Ln(III) shows the highest photocatalytic activity.

4 Conclusions

The decomposition of Malachite Green in model solutions under visible light irradiation in the presence of NiFe2O4 and Zn0.5Ni0.5Fe2O4, pure and modified with Eu(III) and Tb(III), was investigated. It was found that more than 60 % of the dye was decomposed after 150 min under visible light irradiation. The most active photocatalyst among the investigated samples was the three-component mixed metal oxide Zn0.5Ni0.5Fe2O4, modified with 5 wt. % Ln(III), showing a high activity under visible light while the two components ferrite NiFe2O4 shows lower activity. The rate constants under visible light irradiation of the tested catalysts was found to increase in the order of ZNF < ZNF-Eu5 < ZNF-Tb5. The positive influence of Tb(III) and Eu(III) on the photocatalytic activity at visible light irradiation is demonstrated.

The large number of factors influencing the process of decomposition of MG makes it difficult to distinguish and elucidate the role of each of them separately. Considering the lower energy of visible light and the availability of sunlight, the results are rather promising because the activation under visible light means lower cost for the photocatalytic cleaning and simple construction of the testing equipment. It is crucial for the application of the prepared catalysts that they are not hazardous; indeed no dissolution of catalyst metals was detected under the conditions of the photocatalytic test.

Acknowledgements

The support of the operational program “Science and Education for Smart Growth” by Project BG05M2OP001-2.009-0028 is acknowledged.

  1. Conflict of interest: Authors declare no conflict of interest.

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Received: 2018-11-29
Accepted: 2019-05-29
Published Online: 2019-12-18

© 2019 M. P. Tsvetkov et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 Public License.

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  7. Phytic Acid Extracted from Rice Bran as a Growth Promoter for Euglena gracilis
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https://doi.org/10.1515/chem-2019-0116
Keywords for this article
ferrites; lanthanide ions; photocatalytic activity; rate constants; band gap energy
Creative Commons
BY 4.0

Articles in the same Issue

  1. Regular Articles
  2. Research on correlation of compositions with oestrogenic activity of Cistanche based on LC/Q-TOF-MS/MS technology
  3. Efficacy of Pyrus elaeagnifolia subsp. elaeagnifolia in acetic acid–induced colitis model
  4. Anti-inflammatory and antinociceptive features of Bryonia alba L.: As a possible alternative in treating rheumatism
  5. High efficiency liposome fusion induced by reducing undesired membrane peptides interaction
  6. Prediction of the Blood-Brain Barrier Permeability Using RP-18 Thin Layer Chromatography
  7. Phytic Acid Extracted from Rice Bran as a Growth Promoter for Euglena gracilis
  8. Development of a validated spectrofluorimetric method for assay of sotalol hydrochloride in tablets and human plasma: application for stability-indicating studies
  9. Topological Indices of Hyaluronic Acid-Paclitaxel Conjugates’ Molecular Structure in Cancer Treatment
  10. Thermodynamic properties of the bubble growth process in a pool boiling of water-ethanol mixture two-component system
  11. Critical Roles of the PI3K-Akt-mTOR Signaling Pathway in Apoptosis and Autophagy of Astrocytes Induced by Methamphetamine
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  13. Specific, highly sensitive and simple spectrofluorimetric method for quantification of daclatasvir in HCV human plasma patients and in tablets dosage form
  14. Chromium-modified cobalt molybdenum nitrides as catalysts for ammonia synthesis
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  24. Effects of Azadirachta Indica Leaf Extract, Capping Agents, on the Synthesis of Pure And Cu Doped ZnO-Nanoparticles: A Green Approach and Microbial Activity
  25. Aqueous Micro-hydration of Na+(H2O)n=1-7 Clusters: DFT Study
  26. A proposed image-based detection of methamidophos pesticide using peroxyoxalate chemiluminescence system
  27. Phytochemical screening and estrogenic activity of total glycosides of Cistanche deserticola
  28. Biological evaluation of a series of benzothiazole derivatives as mosquitocidal agents
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  30. Dynamic Changes in MMP1 and TIMP1 in the Antifibrotic Process of Dahuang Zhechong Pill in Rats with Liver Fibrosis
  31. The Optimization and Production of Ginkgolide B Lipid Microemulsion
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  59. Biodiesel Production by Lipids From Indonesian strain of Microalgae Chlorella vulgaris
  60. Miscibility studies of polystyrene/polyvinyl chloride blend in presence of organoclay
  61. Antibacterial Activities of Transition Metal complexes of Mesocyclic Amidine 1,4-diazacycloheptane (DACH)
  62. Novel 1,8-Naphthyridine Derivatives: Design, Synthesis and in vitro screening of their cytotoxic activity against MCF7 cell line
  63. Investigation of Stress Corrosion Cracking Behaviour of Mg-Al-Zn Alloys in Different pH Environments by SSRT Method
  64. Various Combinations of Flame Retardants for Poly (vinyl chloride)
  65. Phenolic compounds and biological activities of rye (Secale cereale L.) grains
  66. Oxidative degradation of gentamicin present in water by an electro-Fenton process and biodegradability improvement
  67. Optimizing Suitable Conditions for the Removal of Ammonium Nitrogen by a Microbe Isolated from Chicken Manure
  68. Anti-inflammatory, antipyretic, analgesic, and antioxidant activities of Haloxylon salicornicum aqueous fraction
  69. The anti-corrosion behaviour of Satureja montana L. extract on iron in NaCl solution
  70. Interleukin-4, hemopexin, and lipoprotein-associated phospholipase A2 are significantly increased in patients with unstable carotid plaque
  71. A comparative study of the crystal structures of 2-(4-(2-(4-(3-chlorophenyl)pipera -zinyl)ethyl) benzyl)isoindoline-1,3-dione by synchrotron radiation X-ray powder diffraction and single-crystal X-ray diffraction
  72. Conceptual DFT as a Novel Chemoinformatics Tool for Studying the Chemical Reactivity Properties of the Amatoxin Family of Fungal Peptides
  73. Occurrence of Aflatoxin M1 in Milk-based Mithae samples from Pakistan
  74. Kinetics of Iron Removal From Ti-Extraction Blast Furnace Slag by Chlorination Calcination
  75. Increasing the activity of DNAzyme based on the telomeric sequence: 2’-OMe-RNA and LNA modifications
  76. Exploring the optoelectronic properties of a chromene-appended pyrimidone derivative for photovoltaic applications
  77. Effect of He Qi San on DNA Methylation in Type 2 Diabetes Mellitus Patients with Phlegm-blood Stasis Syndrome
  78. Cyclodextrin potentiometric sensors based on selective recognition sites for procainamide: Comparative and theoretical study
  79. Greener synthesis of dimethyl carbonate from carbon dioxide and methanol using a tunable ionic liquid catalyst
  80. Nonisothermal Cold Crystallization Kinetics of Poly(lactic acid)/Bacterial Poly(hydroxyoctanoate) (PHO)/Talc
  81. Enhanced adsorption of sulfonamide antibiotics in water by modified biochar derived from bagasse
  82. Study on the Mechanism of Shugan Xiaozhi Fang on Cells with Non-alcoholic Fatty Liver Disease
  83. Comparative Effects of Salt and Alkali Stress on Antioxidant System in Cotton (Gossypium Hirsutum L.) Leaves
  84. Optimization of chromatographic systems for analysis of selected psychotropic drugs and their metabolites in serum and saliva by HPLC in order to monitor therapeutic drugs
  85. Electrocatalytic Properties of Ni-Doped BaFe12O19 for Oxygen Evolution in Alkaline Solution
  86. Study on the removal of high contents of ammonium from piggery wastewater by clinoptilolite and the corresponding mechanisms
  87. Phytochemistry and toxicological assessment of Bryonia dioica roots used in north-African alternative medicine
  88. The essential oil composition of selected Hemerocallis cultivars and their biological activity
  89. Mechanical Properties of Carbon Fiber Reinforced Nanocrystalline Nickel Composite Electroforming Deposit
  90. Anti-c-myc efficacy block EGFL7 induced prolactinoma tumorigenesis
  91. Topical Issue on Applications of Mathematics in Chemistry
  92. Zagreb Connection Number Index of Nanotubes and Regular Hexagonal Lattice
  93. The Sanskruti index of trees and unicyclic graphs
  94. Valency-based molecular descriptors of Bakelite network BNmn
  95. Computing Topological Indices for Para-Line Graphs of Anthracene
  96. Zagreb Polynomials and redefined Zagreb indices of Dendrimers and Polyomino Chains
  97. Topological Descriptor of 2-Dimensional Silicon Carbons and Their Applications
  98. Topological invariants for the line graphs of some classes of graphs
  99. Words for maximal Subgroups of Fi24‘
  100. Generators of Maximal Subgroups of Harada-Norton and some Linear Groups
  101. Special Issue on POKOCHA 2018
  102. Influence of Production Parameters on the Content of Polyphenolic Compounds in Extruded Porridge Enriched with Chokeberry Fruit (Aronia melanocarpa (Michx.) Elliott)
  103. Effects of Supercritical Carbon Dioxide Extraction (SC-CO2) on the content of tiliroside in the extracts from Tilia L. flowers
  104. Impact of xanthan gum addition on phenolic acids composition and selected properties of new gluten-free maize-field bean pasta
  105. Impact of storage temperature and time on Moldavian dragonhead oil – spectroscopic and chemometric analysis
  106. The effect of selected substances on the stability of standard solutions in voltammetric analysis of ascorbic acid in fruit juices
  107. Determination of the content of Pb, Cd, Cu, Zn in dairy products from various regions of Poland
  108. Special Issue on IC3PE 2018 Conference
  109. The Photocatalytic Activity of Zns-TiO2 on a Carbon Fiber Prepared by Chemical Bath Deposition
  110. N-octyl chitosan derivatives as amphiphilic carrier agents for herbicide formulations
  111. Kinetics and Mechanistic Study of Hydrolysis of Adenosine Monophosphate Disodium Salt (AMPNa2) in Acidic and Alkaline Media
  112. Antimalarial Activity of Andrographis Paniculata Ness‘s N-hexane Extract and Its Major Compounds
  113. Special Issue on ABB2018 Conference
  114. Special Issue on ICCESEN 2017
  115. Theoretical Diagnostics of Second and Third-order Hyperpolarizabilities of Several Acid Derivatives
  116. Determination of Gamma Rays Efficiency Against Rhizoctonia solani in Potatoes
  117. Studies On Compatibilization Of Recycled Polyethylene/Thermoplastic Starch Blends By Using Different Compatibilizer
  118. Liquid−Liquid Extraction of Linalool from Methyl Eugenol with 1-Ethyl-3-methylimidazolium Hydrogen Sulfate [EMIM][HSO4] Ionic Liquid
  119. Synthesis of Graphene Oxide Through Ultrasonic Assisted Electrochemical Exfoliation
  120. Special Issue on ISCMP 2018
  121. Synthesis and antiproliferative evaluation of some 1,4-naphthoquinone derivatives against human cervical cancer cells
  122. The influence of the grafted aryl groups on the solvation properties of the graphyne and graphdiyne - a MD study
  123. Electrochemical modification of platinum and glassy carbon surfaces with pyridine layers and their use as complexing agents for copper (II) ions
  124. Effect of Electrospinning Process on Total Antioxidant Activity of Electrospun Nanofibers Containing Grape Seed Extract
  125. Effect Of Thermal Treatment Of Trepel At Temperature Range 800-1200˚C
  126. Topical Issue on Agriculture
  127. The effect of Cladophora glomerata exudates on the amino acid composition of Cladophora fracta and Rhizoclonium sp.
  128. Influence of the Static Magnetic Field and Algal Extract on the Germination of Soybean Seeds
  129. The use of UV-induced fluorescence for the assessment of homogeneity of granular mixtures
  130. The use of microorganisms as bio-fertilizers in the cultivation of white lupine
  131. Lyophilized apples on flax oil and ethyl esters of flax oil - stability and antioxidant evaluation
  132. Production of phosphorus biofertilizer based on the renewable materials in large laboratory scale
  133. Human health risk assessment of potential toxic elements in paddy soil and rice (Oryza sativa) from Ugbawka fields, Enugu, Nigeria
  134. Recovery of phosphates(V) from wastewaters of different chemical composition
  135. Special Issue on the 4th Green Chemistry 2018
  136. Dead zone for hydrogenation of propylene reaction carried out on commercial catalyst pellets
  137. Improved thermally stable oligoetherols from 6-aminouracil, ethylene carbonate and boric acid
  138. The role of a chemical loop in removal of hazardous contaminants from coke oven wastewater during its treatment
  139. Combating paraben pollution in surface waters with a variety of photocatalyzed systems: Looking for the most efficient technology
  140. Special Issue on Chemistry Today for Tomorrow 2019
  141. Applying Discriminant and Cluster Analyses to Separate Allergenic from Non-allergenic Proteins
  142. Chemometric Expertise Of Clinical Monitoring Data Of Prolactinoma Patients
  143. Chemomertic Risk Assessment of Soil Pollution
  144. New composite sorbent for speciation analysis of soluble chromium in textiles
  145. Photocatalytic activity of NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by Eu(III) and Tb(III) for decomposition of Malachite Green
  146. Photophysical and antibacterial activity of light-activated quaternary eosin Y
  147. Spectral properties and biological activity of La(III) and Nd(III) Monensinates
  148. Special Issue on Monitoring, Risk Assessment and Sustainable Management for the Exposure to Environmental Toxins
  149. Soil organic carbon mineralization in relation to microbial dynamics in subtropical red soils dominated by differently sized aggregates
  150. A potential reusable fluorescent aptasensor based on magnetic nanoparticles for ochratoxin A analysis
  151. Special Issue on 13th JCC 2018
  152. Fluorescence study of 5-nitroisatin Schiff base immobilized on SBA-15 for sensing Fe3+
  153. Thermal and Morphology Properties of Cellulose Nanofiber from TEMPO-oxidized Lower part of Empty Fruit Bunches (LEFB)
  154. Encapsulation of Vitamin C in Sesame Liposomes: Computational and Experimental Studies
  155. A comparative study of the utilization of synthetic foaming agent and aluminum powder as pore-forming agents in lightweight geopolymer synthesis
  156. Synthesis of high surface area mesoporous silica SBA-15 by adjusting hydrothermal treatment time and the amount of polyvinyl alcohol
  157. Review of large-pore mesostructured cellular foam (MCF) silica and its applications
  158. Ion Exchange of Benzoate in Ni-Al-Benzoate Layered Double Hydroxide by Amoxicillin
  159. Synthesis And Characterization Of CoMo/Mordenite Catalyst For Hydrotreatment Of Lignin Compound Models
  160. Production of Biodiesel from Nyamplung (Calophyllum inophyllum L.) using Microwave with CaO Catalyst from Eggshell Waste: Optimization of Transesterification Process Parameters
  161. The Study of the Optical Properties of C60 Fullerene in Different Organic Solvents
  162. Composite Material Consisting of HKUST-1 and Indonesian Activated Natural Zeolite and its Application in CO2 Capture
  163. Topical Issue on Environmental Chemistry
  164. Ionic liquids modified cobalt/ZSM-5 as a highly efficient catalyst for enhancing the selectivity towards KA oil in the aerobic oxidation of cyclohexane
  165. Application of Thermal Resistant Gemini Surfactants in Highly Thixotropic Water-in-oil Drilling Fluid System
  166. Screening Study on Rheological Behavior and Phase Transition Point of Polymer-containing Fluids produced under the Oil Freezing Point Temperature
  167. The Chemical Softening Effect and Mechanism of Low Rank Coal Soaked in Alkaline Solution
  168. The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst
  169. Special Issue on the International conference CosCI 2018
  170. Design of SiO2/TiO2 that Synergistically Increases The Hydrophobicity of Methyltrimethoxysilane Coated Glass
  171. Antidiabetes and Antioxidant agents from Clausena excavata root as medicinal plant of Myanmar
  172. Development of a Gold Immunochromatographic Assay Method Using Candida Biofilm Antigen as a Bioreceptor for Candidiasis in Rats
  173. Special Issue on Applied Biochemistry and Biotechnology 2019
  174. Adsorption of copper ions on Magnolia officinalis residues after solid-phase fermentation with Phanerochaete chrysosporium
  175. Erratum
  176. Erratum to: Sand Dune Characterization For Preparing Metallurgical Grade Silicon
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