scholarly journals Δ-FeOOH as Support for Immobilization Peroxidase: Optimization via a Chemometric Approach

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 259 ◽  
Author(s):  
Tássia Silva Tavares ◽  
Eduardo Pereira da Rocha ◽  
Francisco Guilherme Esteves Nogueira ◽  
Juliana Arriel Torres ◽  
Maria Cristina Silva ◽  
...  
Keyword(s):  
High Efficiency ◽  
Immobilized Enzyme ◽  
High Surface ◽  
High Surface Area ◽  
Sem Images ◽  
X Ray ◽  
Independent Variables ◽  
Surface Iron ◽  
Chemometric Approach ◽  
Optimized Conditions

Owing to their high surface area, stability, and functional groups on the surface, iron oxide hydroxide nanoparticles have attracted attention as enzymatic support. In this work, a chemometric approach was performed, aiming at the optimization of the horseradish peroxidase (HRP) immobilization process on Δ-FeOOH nanoparticles (NPs). The enzyme/NPs ratio (X1), pH (X2), temperature (X3), and time (X4) were the independent variables analyzed, and immobilized enzyme activity was the response variable (Y). The effects of the factors were studied using a factorial design at two levels (−1 and 1). The biocatalyst obtained was evaluated for the ferulic acid (FA) removal, a pollutant model. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The SEM images indicated changes in material morphology. The independent variables X1 (−0.57), X2 (0.71), and X4 (0.42) presented the significance effects estimate. The variable combinations resulted in two significance effects estimates, X1*X2 (−0.57) and X2*X4 (0.39). The immobilized HRP by optimized conditions (X1 = 1/63 (enzyme/NPs ratio, X2 = pH 8, X4 = 60 °C, and 30 min) showed high efficiency for FA oxidation (82%).

scholarly journals Study of Photodegradation Performance and Ability of Lead Removal of Synthesized Maghemite Nanoparticles Using Ziziphus Jujuba Extract

2021 ◽  
Author(s):  
Abdolhossein Miri ◽  
Atefeh Sadat Sedighi ◽  
Ahmad Najafidoust ◽  
Mehrdad Khatami ◽  
Mina sarani
Keyword(s):  
Heavy Metals ◽  
Methylene Blue ◽  
High Efficiency ◽  
High Surface ◽  
High Surface Area ◽  
Good Alternative ◽  
Lead Removal ◽  
Maghemite Nanoparticles ◽  
X Ray ◽  
Ziziphus Jujuba

Abstract Today, Water pollutants such as heavy metals and dyes are very important dangers to the nature. Metals such as lead, chromium, mercury and arsenic are examples of heavy metals which are toxic to living things, even sometime at the lowest concentrations. For resolve this challenge, Magnetic nanoparticles are attractive compound because of their advantages such as high efficiency, fast recovery capability, high surface area, easy transportation and inexpensive. We presented an easy and eco-friendly route for the synthesis of iron oxide nanoparticles using Ziziphus jujuba extract. In order to determine the physical, chemical and optical properties of the synthesized samples, Fourier-transform infrared (FT-IR), powder X-ray diffraction (PXRD), vibrating sample magnetometer (VSM), field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and Raman analyses were deployed. PXRD results showed that the synthesized nanoparticles have maghemite form of (γ-Fe2O3). FESEM and TEM results demonstrated that the size of these nanoparticles was in range of 20-50 nm, and had spherical shapes. Raman spectrum confirmed the cubic structure of γ-Fe2O3 NPs. Survey of magnetic properties showed that the synthesized maghemite nanoparticles (γ-Fe2O3 NPs) were superparamagnetic. The ability to remove lead from aqueous solution was investigated using these nanoparticles. The results showed that the synthesized nanoparticles were capable of removing 96% of lead at pH = 7 and 1 mg/L loading of nanoparticles. The photocatalytic activity of γ-Fe2O3 NPs was studied on methylene blue (MB) dye; as a result, MB at pH =7 and 1 gr dosage of γ-Fe2O3 had the highest removal percentage (92.8%) during 160 minute using γ-Fe2O3 which calcined at 400 ˚C. The reusability results showed that after four cycles of using the γ-Fe2O3-400, the obtained degradation of methylene blue was about 87.1%. Thus, synthesized γ-Fe2O3 NPs can be a good alternative for removing heavy metals and industrial dyes from contaminated waters.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

scholarly journals Attached β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane to graphene oxide and its application in copper removal

2017 ◽  
Vol 75 (10) ◽  
pp. 2403-2411 ◽  
Author(s):  
Zongxue Yu ◽  
Qi Chen ◽  
Liang Lv ◽  
Yang Pan ◽  
Guangyong Zeng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Esterification Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cavity Structure ◽  
Optimum Ph ◽  
Exchange Adsorption ◽  
Langmuir Isotherm Model

The environmental applications of graphene oxide and β-cyclodextrin (β-CD) have attracted great attention since their first discovery. Novel nanocomposites were successfully prepared by using an esterification reaction between β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane grafted graphene oxide (β-CD/GPTMS/GO). The β-CD/GPTMS/GO nanocomposites were used to remove the Cu2+ from aqueous solutions. The characteristics of β-CD/GPTMS/GO were detected by scanning electron microscopy (SEM), Fourier transform infrared, X-ray diffraction (XRD), thermogravimetric analysis (TG) and energy dispersive X-ray (EDX). The dispersibility of graphene oxide was excellent due to the addition of β-CD. The adsorption isotherms data obtained at the optimum pH 7 were fitted by Langmuir isotherm model. The excellent adsorption properties of β-CD/GPTMS/GO for Cu2+ ions could be attributed to the apolar cavity structure of β-CD, the high surface area and abundant functional groups on the surface of GO. The adsorption patterns of β-CD/GPTMS/GO were electrostatic attraction, formation of host-guest inclusion complexes and the ion exchange adsorption. The efficient adsorption of β-CD/GPTMS/GO for Cu2+ ions suggested that these novel nanocomposites may be ideal candidates for removing other cation pollutants from waste water.

Facile Synthesis of Unique Bismuth Vanadate Nano-Knitted Hollow Cage and its Application in Environmental Remediation

2019 ◽  
Vol 74 (3) ◽  
pp. 259-263 ◽  
Author(s):  
M. Shamshi Hassan
Keyword(s):  
Environmental Remediation ◽  
Dye Degradation ◽  
High Surface ◽  
High Surface Area ◽  
Bismuth Vanadate ◽  
Bandgap Energy ◽  
Blue Dye ◽  
X Ray ◽  
Photodegradation Efficiency ◽  
Hollow Nanostructure

AbstractHierarchical bismuth vanadate (BiVO4) nano-knitted hollow cages have been synthesized by simple hydrothermal method and characterized by scanning electron microscopy, x-ray diffraction, energy-dispersive x-ray spectrometer, Fourier transform infrared, UV-Vis, and Raman. The photodegradation efficiency of BiVO4 nanocage for universally used methylene blue dye. The BiVO4 hollow nanostructure demonstrated better photocatalytic competence in dye degradation as compared to the commercial TiO2 powders (P25). The excellent dye degradation can be certified to the high crystallisation of monoclinic BiVO4 and hollow nanostructure, which leads to high surface area and small bandgap energy of 2.44 eV.

scholarly journals Operando SAXS Study of a Pt/C Fuel Cell Catalyst with an X-ray Laboratory Source

2021 ◽  
Author(s):  
Johanna Schröder ◽  
Jonathan Quinson ◽  
Jacob J. K. Kirkensgaard ◽  
Matthias Arenz
Keyword(s):  
Fuel Cell ◽  
Background Subtraction ◽  
Stress Test ◽  
High Surface ◽  
High Surface Area ◽  
Carbon Support ◽  
Grazing Incidence ◽  
Saxs Data ◽  
X Ray ◽  
Fuel Cell Catalysts

Small angle X-ray scattering (SAXS) is a powerful technique to investigate the degradation of catalyst materials. Ideally such investigations are performed <i>operando</i>, i.e., during a catalytic reaction. An example of <i>operando </i>measurements is to observe the degradation of fuel cell catalysts during an accelerated stress test (AST). Fuel cell catalysts consist of Pt or Pt alloy nanoparticles (NPs) supported on a high surface area carbon. A key challenge of operando SAXS measurements is a proper background subtraction of the carbon support to extract the information of the size distribution of the Pt NPs as a function of the AST treatment. Typically, such operando studies require the use of synchrotron facilities. The background measurement can then be performed by anomalous SAXS (aSAXS) or in a grazing incidence con-figuration. In this work we present a proof-of-concept study demonstrating the use of a laboratory X-ray diffractometer for <i>operando </i>SAXS. Data acquisition of <i>operando </i>SAXS with a laboratory X-ray diffractometer is desirable due to the general challenging and limited accessibility of synchrotron facilities. They become even more crucial under the ongoing and foreseen restrictions related to the COVID-19 pandemic. Although, it is not the aim to completely replace synchrotron-based studies, it is shown that the background subtraction can be achieved by a simple experimental consideration in the setup that can ultimately facilitate <i>operando </i>SAXS measurements at a synchrotron facility. <br>

scholarly journals Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

2014 ◽  
Vol 11 (5) ◽  
pp. 6815-6844
Author(s):  
S. C. Löhr ◽  
M. J. Kennedy
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
X Ray ◽  
Oceanic Anoxic Event ◽  
Carbon Burial ◽  
Anoxic Events ◽  
Mineral Surface Area

Abstract. Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE2 at Demerara Rise was controlled by co-occurrence of anoxic bottom-water, sufficient productivity to saturate available mineral surfaces and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (R2=0.92) occurs across a range of TOC values from 9–33%. X-ray diffraction data indicates intercalation of OC in smectite interlayers while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE2 at Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO2.

scholarly journals Promoting Li/MgO Catalyst with Molybdenum Oxide for Oxidative Conversion of n-Hexane

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 354 ◽  
Author(s):  
Cassia Boyadjian ◽  
Leon Lefferts
Keyword(s):  
Raman Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Deep Oxidation ◽  
Oxidative Conversion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anionic Species ◽  
Dehydrogenation Reactions ◽  
Lithium Molybdate

In this work, molybdena-promoted Li/MgO is studied as a catalyst for the oxidative conversion of n-hexane. The structure of the catalysts is investigated with X-ray Diffraction (XRD) and Raman spectroscopy. The MoO3/Li/MgO catalyst contains three types of molybdena-containing species, the presence of which depend on molybdena loading. At low Mo/Li ratios (i) isolated dispersed [MoO4]2− anionic species are observed. At high Mo/Li ratios, the formation of crystalline lithium molybdate phases such as (ii) monomeric Li2MoO4 and tentatively (iii) polymeric Li2Mo4O13 are concluded. The presence of these lithium molybdates diminishes the formation of Li2CO3 in the catalyst. Subsequently, the catalyst maintains high surface area and stability with time-on-stream during oxidative conversion. Molybdena loading as low as 0.5 wt % is sufficient to induce these improvements, maintaining the non-redox characteristics of the catalyst, whereas higher loadings enhance deep oxidation and oxidative dehydrogenation reactions. Promoting a Li/MgO catalyst with 0.5 wt % MoO3 is thus efficient for selective conversion of n-hexane to alkenes, giving alkene yield up to 24% as well as good stability.

scholarly journals Amorphous Mo5O14-Type/Carbon Nanocomposite with Enhanced Electrochemical Capability for Lithium-Ion Batteries

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 8 ◽  
Author(s):  
Ahmed M. Hashem ◽  
Ashraf E. Abdel-Ghany ◽  
Rasha S. El-Tawil ◽  
Sylvio Indris ◽  
Helmut Ehrenberg ◽  
...  
Keyword(s):  
Oxygen Deficiency ◽  
High Surface ◽  
High Surface Area ◽  
Lithium Ion ◽  
Carbon Matrix ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Thermal Gravimetry ◽  
Type C ◽  
Carbon Nanocomposite

An amorphous MomO3m−1/carbon nanocomposite (m ≈ 5) is fabricated from a citrate–gel precursor heated at moderate temperature (500 °C) in inert (argon) atmosphere. The as-prepared Mo5O14-type/C material is compared to α-MoO3 synthesized from the same precursor in air. The morphology and microstructure of the as-prepared samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman scattering (RS) spectroscopy. Thermal gravimetry and elemental analysis indicate the presence of 25.8 ± 0.2% of carbon in the composite. The SEM images show that Mo5O14 is immersed inside a honeycomb-like carbon matrix providing high surface area. The RS spectrum of Mo5O14/C demonstrates an oxygen deficiency in the molybdenum oxide and the presence of a partially graphitized carbon. Outstanding improvement in electrochemical performance is obtained for the Mo5O14 encapsulated by carbon in comparison with the carbon-free MoO3.

scholarly journals Enhanced Photocatalytic Activity of Titania by Co-Doping with Mo and W

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 631 ◽  
Author(s):  
Osmín Avilés-García ◽  
Jaime Espino-Valencia ◽  
Rubí Romero-Romero ◽  
José Rico-Cerda ◽  
Manuel Arroyo-Albiter ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Absorption Capacity ◽  
Radiation Absorption ◽  
Experimental Conditions ◽  
X Ray ◽  
Assembly Method ◽  
Co Doped

Various W and Mo co-doped titanium dioxide (TiO2) materials were obtained through the EISA (Evaporation-Induced Self-Assembly) method and then tested as photocatalysts in the degradation of 4-chlorophenol. The synthesized materials were characterized by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy (RS), N2 physisorption, UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results showed that the W-Mo-TiO2 catalysts have a high surface area of about 191 m2/g, and the presence of an anatase crystalline phase. The co-doped materials exhibited smaller crystallite sizes than those with one dopant, since the crystallinity is inhibited by the presence of both species. In addition, tungsten and molybdenum dopants are distributed and are incorporated into the anatase structure of TiO2, due to changes in red parameters and lattice expansion. Under our experimental conditions, the co-doped TiO2 catalyst presented 46% more 4-chlorophenol degradation than Degussa P25. The incorporation of two dopant cations in titania improved its photocatalytic performance, which was attributed to a cooperative effect by decreasing the recombination of photogenerated charges, high radiation absorption capacity, high surface areas, and low crystallinity. When TiO2 is co-doped with the same amount of both cations (1 wt.%), the highest degradation and mineralization (97% and 74%, respectively) is achieved. Quinones were the main intermediates in the 4-chlorophenol oxidation by W-Mo-TiO2 and 1,2,4-benzenetriol was incompletely degraded.

Hydrothermal Synthesis and Characterization of Phosphor Doped Tetragonal Zirconia Nanocrystallites

2011 ◽  
Vol 197-198 ◽  
pp. 846-852
Author(s):  
Jian Jun Yin ◽  
Tao Wang ◽  
Wei Jing Xing
Keyword(s):  
Photoelectron Spectroscopy ◽  
Raw Materials ◽  
High Surface ◽  
High Surface Area ◽  
Tetragonal Zirconia ◽  
Zirconium Oxychloride ◽  
Dihydrogen Phosphate ◽  
Hydrothermal Conditions ◽  
Hydrothermal Temperature ◽  
X Ray

Using zirconium oxychloride hydrate ( ZrOCl2•8H2O) and ammonia water (NH3•H2O) as raw materials, and ammonium dihydrogen phosphate (NH4H2PO4) as additives, tetragonal zirconia (t-ZrO2) with size range of 8–12 nm were prepared by coprecipitation method under hydrothermal conditions. The influence factors on phase transformation and the particle size such as phosphor loading, hydrothermal temperature and calcination temperature were studied by X-ray diffraction (XRD), Fourier transform Roman spectra (FT-Roman), the Brunauer-Emmett-Teller (BET) method and X-ray photoelectron spectroscopy (XPS) techniques etc. Research results show that a small amount of phosphor has been incorporated into the framework of ZrO2 crystals, producing a certain amount of oxygen vacancies. Phosphor can effectively restrain crystal particles growth and improve the thermal stability of metastable t-ZrO2. The phosphor doped t-ZrO2 had a high surface area (244.2 m2/g). In contrast to the pure ZrO2 particles readily aggregating, the phosphor species deposited on the framework of ZrO2 crystals prevented the agglomeration of the primary particles during calcinations.

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