scholarly journals Mg-Fe Layered Double Hydroxides Enhance Surfactin Production in Bacterial Cells

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 355 ◽  
Author(s):  
Pei-Hsin Chang ◽  
Si-Yu Li ◽  
Tzong-Yuan Juang ◽  
Yung-Chuan Liu
Keyword(s):  
Layered Double Hydroxides ◽  
Time Course ◽  
Effective Means ◽  
Scale Up ◽  
Molar Ratio ◽  
Bacterial Cells ◽  
High Productivity ◽  
Potential Applications ◽  
Surfactin Production ◽  
Double Hydroxides

In this study, four additives—montmorillonite, activated carbon, and the layered double hydroxides (LDHs), Mg2Fe–LDH and Mg2Al–LDH—were tested for their ability to promote surfactin production in a Bacillus subtilis ATCC 21332 culture. Among these tested materials, the addition of 4 g/L of the Mg-Fe LDH, which featured an Mg/Fe molar ratio of 2:1, produced the highest surfactin yield of 5280 mg/L. During the time course of B. subtilis cultivation with the added LDH, two phases of cell growth were evident: Growth and decay. In the growth phase, the cells grew slowly and secreted a high amount of surfactin; in the decay phase, the cells degraded rapidly. The production in the presence of the Mg2Fe–LDH had three characteristics: (i) High surfactin production at low biomass, indicating a high specific surfactin yield of 3.19 g/g DCW; (ii) rapid surfactin production within 24 h, inferring remarkably high productivity (4660 mg/L/d); and (iii) a lower carbon source flux to biomass, suggesting an efficient carbon flux to surfactin, giving a high carbon yield of 52.8%. The addition of Mg2Fe–LDH is an effective means of enhancing surfactin production, with many potential applications and future industrial scale-up.

Nanohybrid Enzymes - Layered Double Hydroxides: Potential Applications

2006 ◽  
Vol 2 (3) ◽  
pp. 283-294 ◽  
Author(s):  
Claude Forano ◽  
Stephanie Vial ◽  
Christine Mousty
Keyword(s):  
Layered Double Hydroxides ◽  
Potential Applications ◽  
Double Hydroxides

scholarly journals Lysine-Functionalized Layered Double Hydroxides For The Antibiotics’ Efficient Removal: Controllable Fabrication Via BBD Model And Removing Mechanism

2021 ◽  
Author(s):  
Yuying Hu ◽  
Susu Liu ◽  
Min Qiu ◽  
Xiaohuan Zheng ◽  
Xiaoming Peng ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Adsorption Mechanism ◽  
Electrostatic Attraction ◽  
Adsorption Behavior ◽  
Molar Ratio ◽  
Order Kinetic ◽  
Efficient Removal ◽  
Adsorption Processes ◽  
Controllable Fabrication ◽  
Double Hydroxides

Abstract Ly @ FeZn layered double hydroxides (LDHs) controllable fabrication based on Box-Behnken Design (BBD) model was fabricated, and presented stable and efficient removal performance for Ciprofloxacin (CIP), Norfloxacin (NOR) and Ofloxacin (OFL) removal. It should be noted that Ly @ FeZn had different adsorption behavior towards CIP, NOR and OFL. Furthermore, the Ly @ FeZn was characterized by SEM, XRD, FT-IR and XPS. Results revealed the optimized fabrication condition (temperature of 60 °C, Fe / Zn molar ratio of 0.5 and the lysine dosage of 5.8 mmol) for the removing efficient. The highest adsorption capacity of CIP, NOR and OFL were 193.83, 190.20 and 62.12 mg/g, respectively. Adsorption kinetics of both CIP and NOR were well simulated with the pseudo-first-order kinetic model, while that of OFL was well-described by the pseudo-second-order. Moreover, the adsorption thermodynamics of CIP and NOR on Ly @ FeZn indicated that the adsorption processes were exothermal, feasible and spontaneous. It was worth noting that the adsorption mechanism of Ly @ FeZn for CIP and NOR were the synergistic reaction of electrostatic attraction, chemical bonding and flocculation. On the other side, the adsorption behavior of OFL was relatively low, and the adsorption mechanism was only electrostatic attraction.

scholarly journals Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K2HPO4

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 183 ◽  
Author(s):  
Roger Borges ◽  
Fernando Wypych ◽  
Elodie Petit ◽  
Claude Forano ◽  
Vanessa Prevot
Keyword(s):  
Layered Double Hydroxides ◽  
Slow Release ◽  
Mechanochemical Activation ◽  
Molar Ratio ◽  
X Ray ◽  
Dipotassium Hydrogen Phosphate ◽  
Before And After ◽  
Noticeable Improvement ◽  
Slow Release Fertilizers ◽  
Double Hydroxides

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

scholarly journals Curcumin Incorporation into Zn3Al Layered Double Hydroxides—Preparation, Characterization and Curcumin Release

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 244 ◽  
Author(s):  
Octavian D. Pavel ◽  
Ariana Şerban ◽  
Rodica Zăvoianu ◽  
Elena Bacalum ◽  
Ruxandra Bîrjega
Keyword(s):  
Layered Double Hydroxides ◽  
Curcuma Longa ◽  
Nano Particles ◽  
Molar Ratio ◽  
Attenuated Total Reflectance ◽  
Buffer Solutions ◽  
Ph Values ◽  
Main Crystalline Phase ◽  
Ph Increase ◽  
Double Hydroxides

Curcumin (CR) is a natural antioxidant compound extracted from Curcuma longa (turmeric). Until now, researches related to the incorporation of CR into layered double hydroxides (LDHs) were focused only on hybrid structures based on a MgxAl-LDH matrix. Our studies were extended towards the incorporation of CR in another type of LDH-matrix (Zn3Al-LDH) which could have an even more prolific effect on the antioxidant activity due to the presence of Zn. Four CR-modified Zn3Al-LDH solids were synthesized, e.g., PZn3Al-CR(Aq), PZn3Al-CR(Et), RZn3Al-CR(Aq) and RZn3Al-CR(Et) (molar ratio CR/Al = 1/10, where P and R stand for the preparation method (P = precipitation, R = reconstruction), while (Aq) and (Et) indicate the type of CR solution, aqueous or ethanolic, respectively). The samples were characterized by XRD, Attenuated Total Reflectance Fourier Transformed IR (ATR-FTIR) and diffuse reflectance (DR)-UV–Vis techniques and the CR-release was investigated in buffer solutions at different pH values (1, 2, 5, 7 and 8). XRD results indicated a layered structure for PZn3Al-CR(Aq), PZn3Al-CR(Et), RZn3Al-CR(Aq) impurified with ZnO, while RZn3Al-CR(Et) contained ZnO nano-particles as the main crystalline phase. For all samples, CR-release revealed a decreasing tendency towards the pH increase, and higher values were obtained for RZn3Al-CR(Et) and PZn3Al-CR(Et) (e.g., 45% and 25%, respectively at pH 1).

scholarly journals Gas-Phase Hydrogenation of Furfural to Furfuryl Alcohol over Cu-ZnO-Al2O3 Catalysts Prepared from Layered Double Hydroxides

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 486
Author(s):  
Guillermo R. Bertolini ◽  
Carmen P. Jiménez-Gómez ◽  
Juan Antonio Cecilia ◽  
Pedro Maireles-Torres
Keyword(s):  
Gas Phase ◽  
Aging Time ◽  
Layered Double Hydroxides ◽  
Furfuryl Alcohol ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray ◽  
General Chemical ◽  
Co Precipitation ◽  
Double Hydroxides

Several layered double hydroxides (LDHs) with general chemical composition (Cu,Zn)1−xAlx(OH)2(CO3)x/2·mH2O have been synthesized by the co-precipitation method, maintaining a (M2+/M3+) molar ratio of 3, and varying the Cu2+/Zn2+ molar ratio between 0.2 and 6.0. After calcination and reduction steps, Cu/ZnO/Al2O3 catalysts were synthesized. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 thermoprogrammed reduction (H2-TPR), N2 adsorption-desorption at −196 °C, N2O titration, X-ray photoelectron miscroscopy (XPS), NH3-thermoprogramed desorption (NH3-TPD) and CO2- thermoprogrammed desorption (CO2-TPD). The characterization data revealed that these catalysts are mainly meso-and macroporous, where Cu, ZnO and Al2O3 are well dispersed. The catalytic results show that these catalysts are active in the gas-phase hydrogenation of furfural, being highly selective to furfuryl alcohol (FOL) and reaching the highest FOL yield for the catalyst with a Cu2+/Zn2+ molar ratio of 1. In an additional study, the influence of the aging time on the synthesis of the LDHs was also evaluated. The catalytic data revealed that the use of shorter aging time in the formation of the LDH has a beneficial effect on the catalytic behavior, since more disordered structures with a higher amount of available Cu sites is obtained, leading to a higher yield towards FOL (71% after 5 h of time-on-stream at 210 °C).

Adsorption Property of MgAl-NO3 Layered Double Hydroxides to Methyl Orange

2013 ◽  
Vol 750-752 ◽  
pp. 1738-1741
Author(s):  
Jian Hui Yan ◽  
Lu Hong Zhang ◽  
You Gen Tang ◽  
Li Zhang
Keyword(s):  
Methyl Orange ◽  
Adsorption Capacity ◽  
Hydrothermal Method ◽  
Layered Double Hydroxides ◽  
Adsorption Property ◽  
Molar Ratio ◽  
Adsorption Performance ◽  
Ft Ir ◽  
Double Hydroxides

MgAl-NO3 LDHs were prepared by hydrothermal method. The as-prepared samples were characterized by SEM, XRD and FT-IR. The adsorption performance of MgAl-NO3 LDHs to methyl orange (MO) was studied. The effects of Mg/Al molar ratio on the adsorption performance of MgAl-NO3 LDHs were investigated. The results showed that the highest adsorption capacity of 499.98mg/g was obtained when the Mg/Al molar ratio was at 2.5:1.

Effect of Doped Iron on Fluoride Sorption by Calcined MgAlFe-CO3 Layered Double Hydroxides

2013 ◽  
Vol 681 ◽  
pp. 21-25
Author(s):  
Yu Bing Pu ◽  
Jia Rui Wang ◽  
Hong Zheng ◽  
Peng Cai ◽  
Si Yuan Wu
Keyword(s):  
Layered Double Hydroxides ◽  
Synthetic Wastewater ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Fluoride Removal ◽  
Maximum Sorption Capacity ◽  
Fluoride Adsorption ◽  
Maximum Sorption ◽  
Co Precipitation ◽  
Double Hydroxides

A series of MgAlFe-CO3 layered double hydroxides (LDHs) were successfully prepared by co-precipitation method. With synthetic wastewater, the effect of doped iron on fluoride sorption by calcined MgAlFe-CO3 layered double hydroxides (CLDH) under different pH and contact time conditions was investigated. The sorption isotherm data were fitted well to Langmuir isotherm at 25 °C. The maximum sorption capacity of fluoride on CLDH increases first and then decreases with the increase of Fe/Al molar ratio and attains maximum of 71.94 mg/g when Fe/Al molar ratio is 1:2, although doped iron is unfavorable to the regeneration of original layered structure for CLDH after fluoride adsorption. No aluminium in the solution after fluoride adsorption was detected when Fe/Al molar ratio is equal to or larger than 1:2. The results indicate that CLDH with proper Fe/Al molar ratio is a promising candidate as an adsorbent material for fluoride removal from aqueous solutions.

Adsorption of Ink-Jet Inks and Anionic Dyes onto Mg-Al-NO3 Layered Double Hydroxides of Variable Mg:Al Molar Ratio

2010 ◽  
Vol 63 (1) ◽  
pp. 83 ◽  
Author(s):  
Anthony R. Auxilio ◽  
Philip C. Andrews ◽  
Peter C. Junk ◽  
Leone Spiccia
Keyword(s):  
Layered Double Hydroxides ◽  
Molar Ratio ◽  
Anionic Dyes ◽  
Type Curves ◽  
Molar Ratios ◽  
High Affinity ◽  
Ink Jet ◽  
Jet Printing ◽  
Double Hydroxides ◽  
Adsorption Desorption

Layered double hydroxides are materials that show promise as adsorbing media for ink-jet printing. In this work, layered double hydroxides with nitrate as interlayer anions and with variable Mg:Al molar ratios ranging from 2.2 to 8.1 have been synthesized at constant pH by the coprecipitation method and characterized by powder X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, and helium pycnometry techniques. The ability of these materials to adsorb ink-jet inks (BCI-Cyan, BCI-Yellow, and BCI-Magenta) and anionic dyes (CI Acid Blue 9 (AB9), CI Acid Yellow 23 (AY23), and CI Acid Red 37 (AR37)) were investigated. BCI-Yellow was found to have high affinity for material with an Mg:Al molar ratio between 2.2 and 4.0, whereas BCI-Cyan and BCI-Magenta showed a high affinity when the Mg:Al molar ratio was between 4.8 and 5.5. The adsorption isotherms for AB9, AY23, and AR37 on the material with Mg:Al molar ratios 2.2–5.5 exhibited H-type curves, indicating a very strong interaction between the adsorbate and adsorbent. Although there was no clear systematic correlation between the MgsAl molar ratio and the Cm (dye capacity) and Ka (dye affinity), the optimum Mg:Al molar ratio was 4.0, and this material has the potential to be used in Ink-Receptive Layer formulation.

scholarly journals Efficient Thermo-Stability and Smoke-Suppression Properties of La Doping Mg-Al LDHs on PVC Nanocomposites

2021 ◽  
Vol 57 (4) ◽  
pp. 297-308
Author(s):  
Jinjie Zhang ◽  
Bin Xu ◽  
Hengxu Wang ◽  
Fupeng Jin ◽  
Jinfeng Dai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Vinyl Chloride ◽  
Layered Double Hydroxides ◽  
Thermal Aging ◽  
Smoke Suppression ◽  
Molar Ratio ◽  
La Doping ◽  
Poly Vinyl Chloride ◽  
Double Hydroxides

Despite the advantages of the non-flammable, good performance and low price, poly (vinyl chloride) (PVC) still suffer from poor thermal stability, restricting its melting process and applications. Although addition of some heat stabilizers can be used to improve the low thermal stability, so far, they normally compromise the environmental issues and smoke density of PVC during combustion. In this work, a series of La doping Mg-Al layered double hydroxides (LaLDHs) with different molar ratio of La3+ / Al3+ were successfully synthesized by coprecipitation-hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM). The results showed that the as-prepared LaLDHs exhibit plate-like morphology with a lateral size around 100-180 nm. The different as-prepared LaLDHs were introduced into PVC as heat stabilizer to prepare PVC nanocomposites. The thermal stability and smoke suppression of PVC nanocomposites were investigated by TGA, thermal aging, Congo red and smoke density rating test (SDR), respectively. All the results demonstrated that PVC-LaLDHs2 nanocomposites containing 2% LaLDHs2 (the molar ratio of La3+ / Al3+ is 1 / 3) were optimized, which achieved the maximal T50% value of 337.2 oC, minimal SDR value of 45.6%, and prolonged the thermal aging time from less than 10mins to 90mins, respectively thermal stability time from 1242s to 2751s. In addition, the tensile strength and elastic modulus of PVC-LaLDHs2 respectively increased by 84.4% (56.6 MPa) and 75.5% (1019.4 MPa) with little affecting elongation at break of PVC. LDHs (layered double hydroxides); rare earth ions; thermal stability; smoke suppression; poly (vinyl chloride)

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