Applied Energy, Vol.201, 20-33, 2017
Fabrication of microencapsulated phase change materials with TiO2/Fe3O4 hybrid shell as thermoregulatory enzyme carriers: A novel design of applied energy microsystem for bioapplications
This article reported the design and fabrication of a novel applied energy microsystem based on magnetic microencapsulated phase change materials (PCMs) as thermoregulatory enzyme carriers for bioapplications. The PCM-containing microcapsules used as enzyme carriers were first synthesized through the Pickering emulsion templating self-assembly of Fe3O4 nanoparticles onto an n-eicosane core, followed by interfacial polycondensation of titania precursors to form a crystalline TiO2/Fe3O4 hybrid shell. The chemical compositions and crystalline structures of the hybrid shell were examined by energy-dispersive X-ray spectroscopy, X-ray photoelectron (XPS) spectroscopy and X-ray powder diffraction. The microcapsules were found to present a regular spherical morphology with a prefect core-shell structure on the basis of transmission and scanning electronic microscopic observations. Thermal analysis indicated that the microencapsulated n-eicosane not only revealed reliable phase-change performance with a thermal energy-storage efficiency of 53.56% but also exhibited a good thermoregulatory capability. Most of all, Candida rugosa lipase (CRL) was immobilized onto these microcapsules by covalent bonds, and such covalent bonding immobilization was further testified by Fourier-transform infrared spectroscopy and XPS spectroscopy. The separability of the CRL-immobilized microcapsules was determined by magnetic characterization along with a visible magnetic separation experiment. The effect of temperature on biocatalytic activity, storage stability, thermal stability and reusability of free and immobilized CRL were investigated. Compared to conventional TiO2 carriers, the immobilized CRL on the microcapsules designed by this study exhibited a higher biocatalytic activity, longer storage stability, higher thermal stability and better reusability due to the thermoregulatory effectiveness of n-eicosane core. This study may open up a novel direction for the development and applications of microencapsulated PCMs in biotechnological and bioengineering areas. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords:Thermoregulatory enzyme carriers;Magnetic microcapsules;Phase change materials;TiO2/Fe3O4 hybrid shell;Biocatalytic activity;Reusability