Presence Of Lanthanum Research Articles

Potentization of the Toxic Effect of Copper in the Presence of Lanthanum in Bioassays for Daphnia magna Straus (Cladocera, Crustacea)

Potentization of the Toxic Effect of Copper in the Presence of Lanthanum in Bioassays for Daphnia magna Straus (Cladocera, Crustacea)

Effect of Lanthanum Doping on Properties of ZnS Thin Films for Water Splitting

A chemical bath deposition technique was used to create the transparent, finely adherent ZnS and Lanthanum doped ZnS thin films on a glass substrate. The films were obtained in a water bath with reaction solutions containing Zinc, Lanthanum precursors, and trisodium citrate as a complexing agent. The amorphous nature of the films was confirmed by an X-ray diffractometer and the porosity of the films was checked by field emission scanning electron microscope. The presence of Lanthanum in ZnS films was confirmed by EDS. To find the band gap UV-Visible spectroscopy analysis was carried out. The impurity phase and the Raman modes were recognized by Raman spectroscopy. Further studies on the water splitting and photocatalytic degradation of organic dyes using La-ZnS nanomaterials are underway in our laboratory.

Meso-Meso and β-Meso Imine-Bridged Thien-2-yl Porphyrin Dyads: Synthesis, Spectral and Electrochemical Investigations

Imine-bridged meso-meso and β-meso unsymmetrical thien-2-yl porphyrin dyads were synthesized by condensation of meso- and β-formyl derivatives of 5,10,15,20-tetrakis(3-methylthien-2-yl)porphyrinato nickel (II), Ni3MeThP with 5-(5-Aminothien-2-yl)-10,15,20-triphenylporphyrinato nickel(II), Ni5AThPP in the presence of lanthanum(III)triflate catalyst in toluene at 120 °C for 8 h. The structural, photophysical, and redox properties were investigated by 1H NMR, UV/Vis spectral, and electrochemical analysis. The near coplanarity of the linker thien-2-yl group with the central porphyrin π-system, which can influence the electron delocalization of these molecules, is explained using electronic spectroscopy and cyclic voltammetry. The stronger electronic interaction between the two porphyrin units and the increased nonplanarity of the macrocycle brought about by the β-meso imine bridging is indicated by the larger shift of redox potentials in the dyad-2 as compared to the dyad-1 system. The results of the present investigation reveal that the two distinct porphyrin units in dyads interact via their near planar thien-2-yl linker.

In English

Today, the antiviral activity of oxide nanomaterials can be used in the fight against the viral disease COVID-19. It is thought that Ag nanoparticles may bind to the surface glycoprotein of the virus and interfere with the virus’s interaction with epithelial cells, and inhibit virus reproduction by releasing silver ions in the cell. The viruses’ inhibition with RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) genomes by oxide nanocomposites action was presented. In this research, the surface structure of doped CeO2 (La2O3) was studied by nitrogen adsorption-desorption based on BET method. The silver atom’s existence in CeO2 - Ag0 can facilitate the transport of more holes to the surface and can enhance the optical, antivirus activity. The primary particle size of pure cerium dioxide is 7 nm, for CeO2 - Ag composite at 2 and 4 wt. % of silver is 6.5 and 6.9 nm; for La2O3 - Ag 27 and 35 nm, respectively. Cell viability was assessed using an MTT (3-(4,5-Dimethylthiazol 2-yl)-2,5-diphenyltetrazolium bromide) assay after NPs (nanoparticles) exposure, since only viable cells have functional mitochondrial dehydrogenase enzymes that can reduce MTT to formazan. Nanoparticles were non-toxic for BHK-21(Syrian hamster kidney), Hep-2 (Human larynx carcinoma), and MDCK (Canine kidney) cells in concentrations of 10 and 100 μg/ml, while cell viability was within 76÷100 %. La2O3 and CeO2, which contained 4 wt. % of Ag at a concentration of 1000 μg/ml had a lower toxic effect: for BHK-21 cells 68 and 76 % of viable cells, respectively; for Hep-2 - 40 and 36 %, for MDCK - 42 and 48 %; La2O3 and CeO2 with 2 and 5 wt. % of Ag at a concentration of 1000 µg/ml were highly toxic. The level of ВНК-21, Нер-2, and MDCK cells viability was in a range of 7 to 37 %. It has been stated that oxides of cerium and lanthanum have a pronounced virucidal action against the Herpes simplex virus and Influenza A virus by completely inhibiting the development of its cytopathic action. The lanthanum and cerium oxides with 2 and 5 wt. % of silver inhibited the development of the virus’s CPE by more than 5.0 log10 compared to the virus control. The results show that lanthanum and cerium oxides with 2 and 5 wt. % silver have a high virucidal effect against herpes simplex virus type 1. A 1.0÷4.0 log10 reduction in the infectious titer of the Herpes virus synthesized “de novo” in the presence of lanthanum and cerium oxide nanocomposites has been shown.

Biosensors Based on Graphene Oxide Functionalized with Benzothiadiazole-Derived Ligands for the Detection of Cholesterol.

In this work, imidazole- or imidazolium-based benzothiadiazole ligands functionalized on graphene oxide combined with cholesterol oxidase constitute efficient, robust, and easy-to-handle materials with high biosensing activity for the detection of cholesterol by colorimetric methods. The presence of lanthanum(III) supported on graphene oxide as a possible coordinating site for the benzothiadiazole ligands was also evaluated, and its bioactivity was compared to that of the analogous material without the rare-earth metal. Our results demonstrated that graphene oxide functionalized with 4,7-bis-(imidazol-1-yl)-2,1,3-benzothiadiazole exhibited the best performance for the quantification of total cholesterol with a sensitivity of 0.0649 (with lanthanum) and 0.0618 au dL mg-1 (without lanthanum). In addition, these materials presented a better percentage of immobilization (>90%), recovered activity, resistance to storage, and detection range than materials containing 4,7-[1-carboxymethyl-(imidazol-3-ium)]-2,1,3-benzothiadiazole chloride. Therefore, the combination of GO-BTD (Im/Ac)/ChOx (with or without lanthanum) affords efficient biosensors for the colorimetric detection of cholesterol.

Lanpepsy is a novel lanthanide-binding protein involved in the lanthanide response of the obligate methylotroph Methylobacillus flagellatus

Lanthanides were recently discovered as metals required in the active site of certain methanol dehydrogenases. Since then, the characterization of the lanthanome, that is, proteins involved in sensing, uptake, and utilization of lanthanides, has become an active field of research. Initial exploration of the response to lanthanides in methylotrophs has revealed that the lanthanome is not conserved and that multiple mechanisms for lanthanide utilization must exist. Here, we investigated the lanthanome in the obligate model methylotroph Methylobacillus flagellatus. We used a proteomic approach to analyze differentially regulated proteins in the presence of lanthanum. While multiple known proteins showed induction upon growth in the presence of lanthanum (Xox proteins, TonB-dependent receptor), we also identified several novel proteins not previously associated with lanthanide utilization. Among these was Mfla_0908, a periplasmic 19 kDa protein without functional annotation. The protein comprises two characteristic PepSY domains, which is why we termed the protein lanpepsy (LanP). Based on bioinformatic analysis, we speculated that LanP could be involved in lanthanide binding. Using dye competition assays, quantification of protein-bound lanthanides by inductively coupled plasma mass spectrometry, as well as isothermal titration calorimetry, we demonstrated the presence of multiple lanthanide binding sites that showed selectivity over the chemically similar calcium ion. LanP thus represents the first member of the PepSY family that binds lanthanides. Although the physiological role of LanP is still unclear, its identification is of interest for applications toward the sustainable purification and separation of rare-earth elements.

Potentiation of the toxic action of copper in the presence of lanthanum in bioassays for Daphnia magna Straus (Cladocera, Crustacea)

The available data on the combined action of rare earth elements and heavy metals are contradictory. Therefore, the goal of the presented work is relevant – to determine the effects of solutions of copper, lanthanum salts and their equimolar mixtures under controlled conditions for Daphnia magna Straus. It has been established that the death of D. magna over 50% in solutions containing Cu2+ is observed at a calculated concentration of 0.05 mg/L (0.0008 mmol/L), and a similar effect of solutions with La3+ occurs at a dose of 50 mg/L (0.36 mmol/L). The potentiation of the lethal effect of copper in the presence of lanthanum is shown. E.g., in solutions of mixtures of Cu and La salts, where the sum of metals is equimolar to non-lethal concentrations of Cu2+ (0.00016 and 0.0008 mmol/L), 100% death of D. magna is observed after 96 and 24 hours, respectively. Further, the potentiation effect was confirmed in bioassays evaluating the locomotor activity of D. magna. Solutions containing a mixture of “Cu2+ and La3+” (1:1) inhibit the motor activity of daphnia similarly to equimolar solutions containing only Cu2+. Thus, despite the significant difference between the effective lethal and non-lethal concentrations of Cu2+ and La3+ (by 1,000), it was found that under the combined action of equimolar doses of the metals, an increase in the toxicity of copper in the presence of lanthanum is observed.

PHOTOCATALYTIC ACTIVITY OF MESOPOROUS TiO2 (ANATAS) IN THE REACTION OF HYDROGEN RELEASE FROM AQUEOUS-ETHANOLIC MIXTURE

Samples of mesoporous nanocrystalline titanium dioxide (anatase with a crystallite size of about 10 nm) were obtained by a modified sol-gel method in the presence of a template of dibenzo-18-crown-6 and small additives of surfactant (dodecylmethylethylammonium bromide) or ions of lanthanum (III) in butyl alcohol in combination with hydrothermal treatment at 175 °C for 24 hours followed by calcination in air at 500 °C for 4 hours. The photocatalytic activity of the obtained TiO2 samples was investigated in a model reaction of the photocatalytic release of H2 from an aqueous-ethanol mixture. It was found that in all cases the use of hydrothermal treatment significantly increases the photoactivity of the obtained sample, which in some cases is more than 3-4 times higher than the corresponding characteristic for commercial photocatalyst Evonik P25. The key effect of hydrothermal treatment on the increase of photoactivity of the samples is probably the consequence of a drastic increase in the treated samples of pore volume and diameter, as well as a decrease in the size of anatase crystallites. These changes (along with a significant increase in the specific surface area) are greater for samples obtained in the presence of La3+ ions. It is shown that samples of TiO2 microspheres obtained at the same concentrations of reagents in the reaction mixture show slightly higher photocatalytic activity than the corresponding lanthanum-stabilized samples of mesoporous TiO2 powders (micrometer-scale particles are not formed in the presence of lanthanum (III) ions). However, with an increasing concentration of reagents in the reaction mixture, the photocatalytic activity has the sample containing lanthanum. Probably, this can be explained by the high textural characteristics of the TiO2 sample in combination with the peculiarities of its morphology - the formation of secondary nanoparticles of agglomerated formations and the influence of La3+ ions. It is worth noting that the photocatalytic activity of TiO2 samples prepared in the presence of La3+ ions reduces as their specific surface area decreases.

Use of rare earth element (REE)-contaminated acidic water as Euglena gracilis growth stimulator: A strategy for bioremediation and simultaneous increase in biodiesel productivity

Rare earth elements (REEs) have emerged as contaminants in water systems because their use and disposal are on the rise in many industries. To achieve environmentally benign treatment of REE-contaminated acidic water, we examined a strategy that uses Euglena gracilis for the bioremediation of REEs and simultaneous biodiesel production from used biomass. The presence of lanthanum (La3+) in the medium (0–100 µM) stimulated the growth of E. gracilis. The removal efficiency of La3+ was 99.9%, indicating that bioremediation using E. gracilis is feasible. The La3+ treatment accelerated the endocytic activity of E. gracilis and enabled cells to take up more nutrients (glucose and macro/micro elements). Also, La3+ increased the paramylon yield of E. gracilis, with the fatty acid methyl ester (FAME) yield below 3 wt% in both the control and La3+-treated cells. To increase the FAME yield and productivity, wax ester fermentation was conducted under anaerobic conditions. After wax ester fermentation, the FAME yield and productivity of the La3+-treated sample were 9.49 wt% and 78.76 g/L/day, 1.4- and 1.6-fold higher than the yield and productivity of the control sample. Moreover, the series of La treatment and wax ester fermentation enhanced the quality of biodiesel by increasing its saturated fatty acid (SFA) content. We confirmed that other REE species (cerium, neodymium, and a mixture) also stimulated the growth and biodiesel production of E. gracilis. Taken together, our E. gracilis-based bioremediation of REE-contaminated water provides high removal efficiency and a chance to simultaneously improve biodiesel productivity and quality.

Arsenic(V) removal on the lanthanum-modified ion exchanger with quaternary ammonium groups based on iron oxide

In this study, the commercially available iron oxide sorbent with quaternary ammonium groups was modified with lanthanum(III) ions for removing arsenate(V) from water. Several analyses, such as SEM, N2 adsorption–desorption method, FTIR and XPS, were employed to characterize the ion exchanger and explore the adsorption of As(V) ions on Ferrix A33E-La(III) (in the abbreviated form A33E-La(III)). The experimental results revealed much better sorption properties of A33E-La(III) than those of unmodified A33E. After the modification, the maximum sorption capacity of the ion exchanger increased by 55% and the percentage removal at various initial As(V) concentrations was higher. According to the results, the As(V) removal was spontaneous and of the exothermic chemisorption type which proceeded due to the formation of monodentate and bidentate inner-sphere complexes as well as lanthanum arsenate by precipitation. Even after 3 cycles of adsorption–desorption A33E-La(III) could be used for arsenic(V) removal with almost the same initial efficiency. It was found that the presence of lanthanum on the surface of the ion exchanger plays a great role in the adsorption of As(V) from the contaminated water due to changing the mechanism of the process.

Comprehensive Comparative Genomics and Phenotyping of Methylobacterium Species.

The pink-pigmented facultative methylotrophs (PPFMs), a major bacterial group found in the plant phyllosphere, comprise two genera: Methylobacterium and Methylorubrum. They have been separated into three major clades: A, B (Methylorubrum), and C. Within these genera, however, some species lack either pigmentation or methylotrophy, which raises the question of what actually defines the PPFMs. The present study employed a comprehensive comparative genomics approach to reveal the phylogenetic relationship among the PPFMs and to explain the genotypic differences that confer their different phenotypes. We newly sequenced the genomes of 29 relevant-type strains to complete a dataset for almost all validly published species in the genera. Through comparative analysis, we revealed that methylotrophy, nitrate utilization, and anoxygenic photosynthesis are hallmarks differentiating the PPFMs from the other Methylobacteriaceae. The Methylobacterium species in clade A, including the type species Methylobacterium organophilum, were phylogenetically classified into six subclades, each possessing relatively high genomic homology and shared phenotypic characteristics. One of these subclades is phylogenetically close to Methylorubrum species; this finding led us to reunite the two genera into a single genus Methylobacterium. Clade C, meanwhile, is composed of phylogenetically distinct species that share relatively higher percent G+C content and larger genome sizes, including larger numbers of secondary metabolite clusters. Most species of clade C and some of clade A have the glutathione-dependent pathway for formaldehyde oxidation in addition to the H4MPT pathway. Some species cannot utilize methanol due to their lack of MxaF-type methanol dehydrogenase (MDH), but most harbor an XoxF-type MDH that enables growth on methanol in the presence of lanthanum. The genomes of PPFMs encode between two and seven (average 3.7) genes for pyrroloquinoline quinone-dependent alcohol dehydrogenases, and their phylogeny is distinctly correlated with their genomic phylogeny. All PPFMs were capable of synthesizing auxin and did not induce any immune response in rice cells. Other phenotypes including sugar utilization, antibiotic resistance, and antifungal activity correlated with their phylogenetic relationship. This study provides the first inclusive genotypic insight into the phylogeny and phenotypes of PPFMs.

SYNTHESIS, SPECTRAL CHARACTERIZATION AND ANTIFUNGAL STUDIES ON LANTHANUM (III) AND PRASEODYMIUM (III) COMPLEXES WITH N2O2DIAZADIOXAMACROCYCLES

A novel series of N2O2diazadioxamacrocyclic complexes of type [Ln(mac)Cl3] has been synthesized via the condensation reactions of a 3-(phenyl/substituted phenyl)-4-amino-5-hydrazino-1,2,4-triazoles with salicylaldehyde and 1,4-dibromobutane in the presence of lanthanum(III) chloride and praseodymium(III) chloride in ethanol. All the newly synthesized compounds were characterized by elemental analysis, electronic absorption, IR, 1HNMR. The particle size of the complexes have been calculated from XRD spectral using Debye-Scherrer formula and these are found to be in 29-31 nm range. In order to evaluate the biological activity of Schiff bases and to assess the role of Ln(III) and Pr(III) metal on biological activity, the hydrazine triazole Schiff bases and their lanthanide complexes have been studies for in vitro antifungal activity against Fusariumoxysporum, CurvularialunataandColletotrichumfalcatum.

Modeling and Box-Behnken design optimization of photocatalytic parameters for efficient removal of dye by lanthanum-doped mesoporous TiO2

In the present study, the Box-Behnken design in the response surface methodology (RSM) was availed to investigate the modelization and optimization of Methyl Orange (MO) mineralization parameters. The process was carried out in the presence of lanthanum (La) doped mesoporous titanium dioxide (TiO2) by a simple impregnation method using various La doping amounts (0.5, 1.5 and 3 wt%). The physico-chemical characteristics of each catalysts are studied under several approaches. The effects of the wavelength of irradiation light, catalysts weight and MO concentration on the yield of MO mineralization were investigated. Based on ANOVA analysis, the results show that the response of MO mineralization (R) in photocatalytic process was significantly affected by a positive individual effect of wavelength and catalyst weight. However, the individual effect of MO concentration has an antagonist impact through the whole process. The optimum conditions were achieved for the light irradiation wavelength of 310 nm, catalyst weight of 80 mg, and MO concentration of 20 ppm, which allowed reaching 99.89 % of mineralization. Overall, the adjusted coefficient of determination (R2) value of 0.9956 indicated that the used model was quite suitable and the selected RSM was successful in optimizing the mineralization conditions of MO.

Comparison of the Crystalline Structure and Magnetic Properties in Coprecipitated CoFe<sub>2</sub>O<sub>4</sub> and CoLa<sub>0.1</sub>Fe<sub>1.9</sub>O<sub>4</sub>

Comparison of the crystalline structure and magnetic properties in CoFe2O4 and CoLa0.1Fe1.9O4 nanoparticles have been studied. The obtained samples are characterized by using X-Ray Diffractometer (XRD), Fourier Transform InfraRed (FTIR) and Vibrating Sample Magnetometer (VSM). The XRD results show that the crystallite size of the samples are 24.539 nm and 28.772 nm for the CoFe2O4 and CoLa0.1Fe1.9O4 nano particles, respectively. Furthermore, the crystalline strain is 0.00460 and lightly decreases to 0.00392 with the presence of lanthanum. The different of the atomic radius for both Fe3+ (1.26 Å) and La3+ (1.87 Å) should attribute to the change of the crystalline strain. FTIR results show that the absorption peak of the CoFe2O4 occur at k = 591.21/cm and the CoLa0.1Fe1.9O4 is 594.10/cm. This indicate that the lanthanum cation successfully substitutes to the original bonding-structure of the CoFe2O4. VSM results show that the HC are 1.02 kOe and 0.705 kOe for the samples without and with La3+ cations. Moreover, the MS is equal 69.625 emu/g and decrease of 55.70 emu/g with the present of the La3+ cations. Finally, the strains-induce-magnetism should contribute to the changes of the MS that associated with changes in crystalline strains at the previous discussion.

Endocytosis in microcystis aeruginosa accelerates the synthesis of microcystins in the presence of lanthanum(III)

Microcystis aeruginosa bloom releases microcystins (MCs) into global aquatic environment, which other living organisms can ingest the released MCs. The toxic effects of MCs on organisms are amplified through the food chain, threatening human and animal health. Lanthanum(III) [La(III)], a pollutant in aquatic environments worldwide, has been confirmed to stimulate MC synthesis in M. aeruginosa. However, the involved cellular mechanism remains unclear. Here, using interdisciplinary approaches, it was first observed that La(III) activated the clathrin-mediated endocytosis in M. aeruginosa. This allowed the algal cells to rapidly absorb macro-elements (C, N and P) and micro-elements (K, Ca and Mg) through the clathrin-mediated endocytosis. These in turn stimulated chlorophyll production, photosynthesis, the growth of the algal cells, and the increases in the productions of MC-LW, MC-LR and MC-YR in M. aeruginosa. These results provide valuable insights for understanding the involved cellular mechanism on MC synthesis and managing MC pollution, which is important to protect global food chain and the ecosystem.

Crystal Structure and Lattice Parameter Investigation of La3+ Substituted CeO2 in LaxCe1-xO2-X/2 Synthesized by Solid-State Method

Lanthanum (La) doped Ceria (CeO2) has attracted considerable interest as a candidate material for thermal barrier coating (TBC) because of its low thermal conductivity and potential capability to be operated above 1250°C. In this study, La2Ce2O7 powder was synthesized through the ball mill method. The crystal structure of La3+ substituted CeO2 solid solution was investigated by X-ray diffraction in LaxCe1-xO2-x/2 (0<x< 0.5). The fluorite structure of CeO2 did not change although La3+ was the largest trivalent rare-earth ion. The lattice parameter changed from 5.41 to 5.59A by increasing La content. Changes in the lattice parameters of LaxCe1-xO2-x/2 that were compared with the theoretical values measured by XRD were obtained based on the oxygen vacancy model. The theoretical lattice parameters were larger than the lattice parameters calculated from the X-ray diffraction pattern. Moreover, the Williamson–Hall equation was used to measure the crystallite size and strain in the LaxCe1-xO2-x/2 lattice as a function of the lanthanum content. The results showed that the presence of lanthanum in the structure reduced the crystallite size.

Preparation of Azido Polycarbonates via Bulk Polymerization of Halogenated Diols

AbstractAzido polymers find use as energetic binders in a variety of composite explosive and propellant applications, but few azido polyesters have previously been reported: a method is introduced for the preparation of two azido polycarbonates, poly(2,2’‐bisazidomethyl‐1,3‐propyl carbonate) and poly(3‐azido‐1,2‐propyl carbonate), possible binder candidates for energetics applications. The preparation method for these polymers involves a two‐step synthesis starting from the bulk polymerization of the commercially sourced diols with diphenyl carbonate in the presence of lanthanum (III) acetylacetonate as a neutral catalyst, and subsequent azidation in cyclohexanone. The physical and thermal characteristics of each are reported, indicating properties similar to other azido‐polymers. The thermal and mechanical properties of cured azido polyester resin mixtures are the subject of ongoing research.

Distribution of lanthanum carbonate in the gastric mucosa confirmed by electron microscopy with a magnified endoscopy: a case report and literature review

We describe the case of a 70-year-old man with diabetic nephropathy undergoing hemodialysis. Four years following hemodialysis, he started taking lanthanum carbonate 1500 mg/day and lansoprazole 30 mg/day. Nine years following hemodialysis, he underwent screening esophagogastroduodenoscopy, which demonstrated the presence of the whitish cobblestone-like mucosa in the gastric corpus and multiple reddish depressed lesions with annular whitish mucosa in the antrum. With magnified narrow-band imaging endoscopy, a yellowish–white substance was observed in the villous structure, and subepithelial vessels were observed on the yellowish–white substance. Biopsies were taken from the whitish cobblestone-like mucosa of the upper corpus, a reddish depressed part of the antrum. Histologically, aggregates of cells containing amphophilic fine granular material were found in the mucosal interstitium. These cells stained positive for CD68 and were identified as histiocytes. Since he had been taking lanthanum carbonate for 5 years, we considered the possibility of histiocyte-mediated phagocytosis of lanthanum. Digital mapping via scanning electron microscopy with energy-dispersive X-ray spectrometry showed the presence of lanthanum and phosphorus in the interstitium and cytoplasm of histiocytes. The white, rough mucosa in the gastric body appeared 6 months following the commencement of lanthanum administration and still exists 3 years and 5 months after discontinuation of lanthanum.

Ni/Al2O3-La2O3 catalysts synthesized by a one-step polymerization method applied to the dry reforming of methane: effect of precursor structures of nickel, perovskite and spinel

Ni catalysts supported on alumina with various lanthanum contents were prepared by the one-step polymerization method to form catalytic precursors that allow better dispersion of the active nickel metal and improve the Ni-La interaction in catalysts containing Ni, Al and La. The characterization of the materials was performed by XRD analysis, N2 adsorption–desorption, H2-temperature programmed reduction, CO2 and H2-temperature programmed desorption and scanning electron microscopy. The catalytic tests were conducted over a period of 6 h and with a stoichiometric ratio of CH4:CO2 equal to 1. The addition of lanthanum in the catalysts led to the formation of LaNiO3 and LaAlO3 perovskites, with a significant reduction of the specific surface area. The catalysis without the presence of lanthanum (NiAl) presented higher methane conversion during the catalytic test but the NiAlLa0.5 catalyst showed highest catalytic activity when considered the number of active sites exposed for reaction. In addition, it was observed that the formation of LaNiO3 perovskite reduces the sintering of the active phase, increasing the degree of dispersion of the catalysis and provides better Ni-La interaction in dry reforming of methane.

Sonocatalytic decolorization of methylene blue from aqueous media by La:ZnO/GO nanocomposites

The collaboration of graphene oxide and a rare earth element dopant has a significant effect on the catalytic performance of zinc oxide nanoparticles (ZnO). For this purpose, lanthanum-doped zinc oxide/graphene oxide (La:ZnO/GO) nanocomposites were produced. The La:ZnO/GO composites developed using various quantities of La3+ (3, 6 and 9 at.%) were used for methylene blue (MB) decomposition in the presence of ultrasound. SEM images of nanocomposites showed that the growth pattern of ZnO nanoparticles on the surface of graphene oxide changed, which can be related to lanthanum addition on the structure. In fact, by adding lanthanum, the structure of ZnO nanosheets that were aggregated in the flower form was converted into flower-like nanorods. TEM images clearly displayed La:ZnO/GO nanorods. The presence of lanthanum was confirmed by EDS analysis. La:ZnO(3 at.%)/GO nanocomposite, exhibited the highest sonocatalytic activity (93% after 80 min) and demonstrated good stability in optimized conditions (catalyst dosage 0.1 g, initial dye concentration 10 mg/L and irradiation time 80 min), which was checked out using response surface methodology from Design of Experiment software. After using a radical hydroxyl, superoxide and hole quencher results confirmed that the generated holes in the valence band of ZnO and superoxide radicals are major species for the MB oxidation process. The results demonstrated that the mineralization percentage of MB was approximately 93% of total organic carbon removal under ultrasound.