Operational Stability, Regenerability, and Thermodynamics Studies on Biogenic Silica/Magnetite/Graphene Oxide Nanocomposite-Activated <i>Candida rugosa</i> Lipase
Inorganic biopolymer-based nanocomposites are useful for stabilizing lipases for enhanced catalytic performance and easy separation. Herein, we report the operational stability, regenerability, and thermodynamics studies of the ternary biogenic silica/magnetite/graphene oxide nanocomposite (SiO<s...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/377502cf64c748a1abf277731881b3c7 |
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| Sumario: | Inorganic biopolymer-based nanocomposites are useful for stabilizing lipases for enhanced catalytic performance and easy separation. Herein, we report the operational stability, regenerability, and thermodynamics studies of the ternary biogenic silica/magnetite/graphene oxide nanocomposite (SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO) as a support for <i>Candida rugosa</i> lipase (CRL). The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field-electron scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), and nitrogen adsorption/desorption data on the support and biocatalyst corroborated their successful fabrication. XPS revealed the Fe<sub>3</sub>O<sub>4</sub> adopted Fe<sup>2+</sup> and Fe<sup>3+</sup> oxidation states, while XRD data of GO yielded a peak at 2θ = 11.67°, with the SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO revealing a high surface area (≈261 m<sup>2</sup>/g). The fourier transform infrared (FTIR) spectra affirmed the successful fabricated supports and catalyst. The half-life and thermodynamic parameters of the superparamagnetic immobilized CRL (CRL/SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO) improved over the free CRL. The microwave-regenerated CRL/SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO (≈82%) exhibited higher catalytic activity than ultrasonic-regenerated (≈71%) ones. Lower activation (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>E</mi><mi>a</mi></msub><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> and higher deactivation energies (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>E</mi><mi>d</mi></msub><mo stretchy="false">)</mo></mrow></semantics></math></inline-formula> were also noted for the CRL/SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO (13.87 kJ/mol, 32.32 kJ/mol) than free CRL (15.26 kJ/mol, 27.60 kJ/mol). A peak at 4.28 min in the gas chromatograph-flame ionization detection (GC-FID) chromatogram of the purified ethyl valerate supported the unique six types of 14 hydrogen atoms of the ester (CAS: 539-82-2) in the proton nuclear magnetic resonance (<sup>1</sup>H-NMR) data. The results collectively demonstrated the suitability of SiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub>/GO in stabilizing CRL for improved operational stability and thermodynamics and permitted biocatalyst regenerability. |
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