scholarly journals Ethyl Butyrate Synthesis Catalyzed by Lipases A and B from Candida antarctica Immobilized onto Magnetic Nanoparticles. Improvement of Biocatalysts’ Performance under Ultrasonic Irradiation

2019 ◽  
Vol 20 (22) ◽  
pp. 5807 ◽  
Author(s):  
Rodolpho R. C. Monteiro ◽  
Davino M. Andrade Neto ◽  
Pierre B. A. Fechine ◽  
Ada A. S. Lopes ◽  
Luciana R. B. Gonçalves ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Ultrasonic Irradiation ◽  
Candida Antarctica ◽  
Ethyl Butyrate ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Ultrasound Technology ◽  
Magnetic Nanomaterial ◽  
Co Precipitation ◽  
Optimized Conditions

The synthesis of ethyl butyrate catalyzed by lipases A (CALA) or B (CALB) from Candida antarctica immobilized onto magnetic nanoparticles (MNP), CALA-MNP and CALB-MNP, respectively, is hereby reported. MNPs were prepared by co-precipitation, functionalized with 3-aminopropyltriethoxysilane, activated with glutaraldehyde, and then used as support to immobilize either CALA or CALB (immobilization yield: 100 ± 1.2% and 57.6 ± 3.8%; biocatalysts activities: 198.3 ± 2.7 Up-NPB/g and 52.9 ± 1.7 Up-NPB/g for CALA-MNP and CALB-MNP, respectively). X-ray diffraction and Raman spectroscopy analysis indicated the production of a magnetic nanomaterial with a diameter of 13.0 nm, whereas Fourier-transform infrared spectroscopy indicated functionalization, activation and enzyme immobilization. To determine the optimum conditions for the synthesis, a four-variable Central Composite Design (CCD) (biocatalyst content, molar ratio, temperature and time) was performed. Under optimized conditions (1:1, 45 °C and 6 h), it was possible to achieve 99.2 ± 0.3% of conversion for CALA-MNP (10 mg) and 97.5 ± 0.8% for CALB-MNP (12.5 mg), which retained approximately 80% of their activity after 10 consecutive cycles of esterification. Under ultrasonic irradiation, similar conversions were achieved but at 4 h of incubation, demonstrating the efficiency of ultrasound technology in the enzymatic synthesis of esters.

scholarly journals Lipase NS81006 immobilized on Fe3O4 magnetic nanoparticles for biodiesel production

2016 ◽  
Vol 27 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Baskar Thangaraj ◽  
Zhaohua Jia ◽  
Lingmei Dai ◽  
Dehua Liu ◽  
Wei Du
Keyword(s):  
Magnetic Nanoparticles ◽  
Immobilized Lipase ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Fe3o4 Magnetic Nanoparticles ◽  
Time Duration ◽  
Fast Reaction ◽  
Functionalized Magnetic Nanoparticles ◽  
Optimized Conditions ◽  
Free Lipase

Abstract Lipase-catalyzed biodiesel production is being the object of extensive research due to the demerits of chemical based catalytic system. Lipase immobilized on Fe3O4 magnetic nanoparticles has the integrated advantages of traditional immobilized lipase and free lipase for its rather fast reaction rate and easy separation. It has been demonstrated that free lipase NS81006 has potential in catalyzing the alcoholysis of renewable oils for biodiesel preparation. In this study, Fe3O4 magnetic nanoparticles functionalized with organosilane compounds like (3-aminopropyl)triethyloxysilane (APTES) and (3-mercaptopropyl)trimethoxysilane) MPTMS were used as carriers for lipase immobilization. Lipase NS81006 was covalently bound to the organosilane-functionalized magnetic nanoparticles by using glutaraldehyde cross-linking reagent. A biodiesel yield of 89% and 81% could be achieved by lipase immobilized on APTES-Fe3O4 and MPTMS-Fe3O4 magnetic nanoparticles respectively under optimized conditions of oil to methanol molar ratio 1:3 with three step addition of methanol, reaction temperature 45°C and reaction time duration 12 h. The lipases immobilized on magnetic nanoparticles could be recovered easily by external magnetic field for further use.

Preparation and characterization of iron oxide nanoparticles coated with chitosan for removal of Cd(II) and Cr(VI) from aqueous solution

2014 ◽  
Vol 70 (6) ◽  
pp. 1004-1010 ◽  
Author(s):  
Th. I. Shalaby ◽  
N. M. Fikrt ◽  
M. M. Mohamed ◽  
M. F. El Kady
Keyword(s):  
Electron Microscope ◽  
Magnetic Nanoparticles ◽  
Magnetic Nanomaterials ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Toxic Heavy Metals ◽  
Transmission Electron ◽  
Magnetite Fe3o4 ◽  
Co Precipitation

This study investigated the applicability of magnetite Fe3O4 nanoparticles coated with chitosan (CMNs) for the removal of some toxic heavy metals from simulated wastewater. Magnetic nanomaterials were synthesized using the co-precipitation method and characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, and Fourier transformer infrared spectroscopy. The magnetic properties of the prepared magnetic nanoparticles were determined by a vibrating-sample magnetometer. Batch experiments were carried out to determine the adsorption kinetics of Cr(VI) and Cd(II) by magnetic nanoparticles. It is noteworthy that CMNs show a highly efficient adsorption capacity for low concentration Cr(VI) and Cd(II) ions solution, which can reach 98% within 10 min.

Co-Precipitation Synthesis of BiFeO3 Powders

2010 ◽  
Vol 105-106 ◽  
pp. 286-288 ◽  
Author(s):  
Hai Yang Bo ◽  
Guo Qiang Tan ◽  
Hong Yan Miao ◽  
Ao Xia
Keyword(s):  
Calcination Temperature ◽  
Bismuth Ferrite ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Infrared Spectrophotometer ◽  
Lower Temperature ◽  
Co Precipitation

Bismuth ferrite powders were synthesized by a simple citric acid complexing co-precipitation method at much lower temperature of 600°C. The work studies the calcination temperature and molar ratio of Fe and Bi on the structure and morphology. The as-prepared BiFeO3 powder was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope and Fourier transform infrared spectrophotometer. The result shows that the phase pure BiFeO3 powders with cubic morphology were prepared as the calcination temperature was 600°C and molar ratio of Fe and Bi was 1:1. The nanoparticles was uniform with the size of about 200nm.

Fabrication of CoFe/BaFe12O19 Magnetic Nanocomposite Thin Films by Electrodeposition

2013 ◽  
Vol 829 ◽  
pp. 332-336
Author(s):  
Soheila Kharratian Khameneh ◽  
M. Heydarzadeh Sohi ◽  
Abolghasem Ataie ◽  
Saeed Mehrizi
Keyword(s):  
Thin Films ◽  
Barium Hexaferrite ◽  
Average Crystallite Size ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Nanocomposite Thin Films ◽  
Co Precipitation ◽  
Deposited Films ◽  
Dominant Phase

A study of the incorporation of barium hexaferrite nanoparticles into a CoFe matrix by means of electrodeposition over brass substrates has been performed. Barium hexaferrite nanoparticles were prepared by co-precipitation route using solution of iron and barium nitrates with a Fe3+/Ba2+molar ratio of 8, by addition of NaOH with a OH-/NO3- molar ratio of 2. X-ray diffraction (XRD) results indicated that in a sample synthesized from aqueous solution and annealed at 900 °C for 1 hour, BaFe12O19 was the dominant phase. Field emission scanning electron microscopy (FE-SEM) showed plate-like particles of barium hexaferrite by mean diameter of 300 nm and thickness of 45 nm. CoFe-BaFe12O19 nanocomposite thin films were then electrodeposited froma Co-Fe bath containing the barium hexaferrite particles obtained in the first stage of this work. Finally, FE-SEM equipped with energy dispersive spectroscopy (EDS) analyzer and XRD analysis was applied on the deposited films, to confirm presence of the nanoparticles in the film. The average crystallite size of the deposits was around 30 nm. It was also noticed that increasing the concentration of the particles in the electroplating bath, caused a rise in the BaFe12O19 content of the deposits but had no significant effect on the composition of the CoFe matrix.

Removal of Cd2+ from Aqueous Solution Using MgAlCO3 -Layered Double Hydroxide

2011 ◽  
Vol 8 (2) ◽  
pp. 13 ◽  
Author(s):  
Nurul Izza Taib ◽  
Norzuyanti Mohd Aris
Keyword(s):  
Contact Time ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Initial Concentration ◽  
Adsorbent Dosage ◽  
Freundlich Isotherms ◽  
Exothermic Process ◽  
Temperature And Pressure ◽  
Co Precipitation ◽  
Double Hydroxide

Anion clay hydrotalcite MgAlCO3 with a Mg/Al molar ratio of 3:1 was synthesized by co-precipitation at room temperature and pressure. The physicochemical properties were evaluated using Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA). The efficacy of anion clay hydrotalcite in the removal of Cd2+ from aqueous solutions was investigated with respect to contact time, initial concentration, pH, adsorbent dosage and temperature. The Cd2+ removal increased with the increased in contact time, adsorbent dosage, pH and initial concentration. Adsorption decreases with increasing initial concentration and temperature, for which the latter is indicative of an exothermic process. The equilibrium adsorption capacity of MgAlCO3 was evaluated using linear Langmuir and Freundlich isotherms with respect to the separation factor, RL .

Preparation of Nickel and Manganese Dioxide by Co-Precipitation and its Electrochemical Capacitive Properties

2015 ◽  
Vol 814 ◽  
pp. 86-90
Author(s):  
Qian Qian Li ◽  
Run Hua Fan ◽  
Yu Jun Bai ◽  
Chuan Bing Cheng ◽  
Gui Fang Liu ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Manganese Oxides ◽  
Electrochemical Impedance ◽  
Spherical Particles ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Capacitive Properties ◽  
Co Precipitation ◽  
Redox Capacitance

The precursor nickel and manganese carbonates were synthesized by co-precipitation with sodium carbonate as precipitant, and then nickel and manganese oxides were gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical characterization was performed using cyclic voltammetry (CV), galvanostatic charge–discharge tests (GCD) and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result showed that the products were the mixture of nickel and manganese oxides and solid solution. nanoparticles and spherical particles were gained by controlling the molar ratio of nickel and manganese. All of the samples exhibited typical Faradic redox capacitance. The specific capacitance was different with the change of nickel and manganese molar ratio. The specific capacitance (Cs) reached 130F/g at 1A/g when the ratio was 2:1.

scholarly journals Synthesis and characterization of iron oxide magnetic nanoparticles

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 73-77 ◽  
Author(s):  
Zbigniew Surowiec ◽  
Mieczysław Budzyński ◽  
Katarzyna Durak ◽  
Grzegorz Czernel
Keyword(s):  
Magnetic Nanoparticles ◽  
Ammonia Concentration ◽  
Blocking Temperature ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Iron Oxide Magnetic Nanoparticles ◽  
Means Of Transmission ◽  
Co Precipitation

Abstract Small particles of magnetite, i.e. 7.5, 13.4 and 14.1 nm in diameter, were obtained by the method of co-precipitation. The crystal structure and size distributions were determined by means of transmission electron microscopy and X-ray diffraction. The magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy within the temperature range from 3 K to room temperature (RT). The Mössbauer study of magnetic nanoparticles reveals relaxation behaviour related to the existence of the superparamagnetic phase. The blocking temperature depends on the sizes of the nanoparticles and the ammonia concentration.

scholarly journals Influence of Cr/Zr Ratio on Activity of Cr–Zr Oxide Catalysts in Non-Oxidative Propane Dehydrogenation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1435
Author(s):  
Alexander Zubkov ◽  
Tatiana Bugrova ◽  
Mikhail Salaev ◽  
Grigory Mamontov
Keyword(s):  
Oxide Catalysts ◽  
Propane Dehydrogenation ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Mixed Oxide Catalysts ◽  
Uv Visible ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Adsorption Desorption

Two series of chromium–zirconium mixed oxide catalysts with different Cr/Zr molar ratio are prepared by co-precipitation method. Porous structure of the catalysts is studied by low-temperature N2 adsorption–desorption. Phase composition and chromium states in the catalysts are characterized by X-ray diffraction (XRD), UV-visible spectroscopy, and temperature-programmed reduction with hydrogen (TPR-H2). The mixed catalysts are tested in non-oxidative dehydrogenation of propane at 550 °C. The catalysts synthesized without ageing of precipitate show higher activity in propane dehydrogenation due to the higher content of reducible Cr+5/+6 species due to its stabilization on the ZrO2 surface.

scholarly journals Removal of Lead from Aqueous Solution by Adsorption using Magnesium Aluminium Hydrogenphosphate Layered Double Hydroxides

2014 ◽  
Vol 8 (1) ◽  
Author(s):  
Zaini Hamzah ◽  
Mohd Najif Ab Rahman ◽  
Yamin Yasin ◽  
Siti Mariam Sumari ◽  
Ahmad Saat
Keyword(s):  
Aqueous Solution ◽  
Layered Double Hydroxide ◽  
Molar Ratio ◽  
Maximum Adsorption Capacity ◽  
Lead Removal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Double Hydroxide ◽  
Double Hydroxides

Layered double hydroxide with molar ratio of 4 (MAN 4) was synthesized by co-precipitation and followed by hydrothermal method. The compound was then later going through ion exchange with K2HPO4 for 48 hours to produce MgAlHPO4 (MAHP 4). The solid produced were characterized using X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). Adsorption of lead solution by MAHP 4 was carried out using batch experiment by mixing the lead solution and the solid of layered double hydroxide. The effects of various parameters such as contact time, pH, adsorbent dosage and initial concentration were investigated. The optimum pH for lead removal was found to be at pH of 5 and the optimum time of lead removal was found at 2 hours. The isotherm data was analysed using Langmuir and the correlation coefficient of 0.998 was obtained. The maximum adsorption capacity, Qo (mg/g) of 500 mg/g was also recorded from the Langmuir isotherm. The remaining lead solution was determined by using EDXRF (Energy Dispersive X-Ray Fluorescence spectrometry) model MiniPal 4 (PAN analytical). The results in this study indicate that MAHP 4 was an interesting adsorbent for removing lead from aqueous solution.

Effect of Gallium Loading on Reducibility and Dispersion of Copper-Based Catalyst

2015 ◽  
Vol 659 ◽  
pp. 211-215
Author(s):  
Parncheewa Udomsap ◽  
Somsak Supasitmongkol
Keyword(s):  
Copper Oxide ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Reduction Peak ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Copper Phase ◽  
Temperature Programmed ◽  
Co Precipitation

The effect of gallium-promoted copper-based catalysts has been investigated in connection with the characteristic of the active copper phase. CuO-ZnO-Ga2O3catalysts with different gallium loadings were prepared using oxalate co-precipitation method. The effects of gallium loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature-programmed reduction (TPR). The dispersion and metal area of copper were also determined by dissociative nitrous (N2O) adsorption technique conducted on a metal dispersion analyzer (BELCAT). The TPR profiles showed that the presence of two different reduction regions in the CuO-ZnO catalysts can be attributed to the reduction of highly dispersed copper oxide species (reduced at 246 °C) and bulk-like CuO (reduced at above 390 °C). By contrast, the only low-temperature reduction peak was presented in the TPR profiles after the Ga2O3loading was higher than 4 wt%. With the same molar ratio (Cu/Zn = 2:1), the reducibility of CuO-ZnO-Ga2O3was found to be more facile than CuO-ZnO due to the lower copper oxide crystallite sizes of gallium-promoted catalysts. Higher Ga2O3loadings resulted in an increase in both copper dispersion and metal surface area of all the catalysts studied in good agreement with the reduction behaviors in the TPR profiles, although all the gallium-promoted catalysts were slightly different for the reducibility.

Sign in / Sign up

Export Citation Format

Share Document