Hierarchically 3-D Porous Structure of Silk Fibroin-Based Biocomposite Adsorbent for Water Pollutant Removal

This study explored the tunability of a 3-D porous network in a freeze-dried silk fibroin/soursop seed (SF:SS) polymer composite bioadsorbent. Morphological, physical, electronic, and thermal properties were assessed using scanning electron microscopy, the BET N<sub>2</sub> adsorption-de...

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Autores principales: Lusi Ernawati, Ruri Agung Wahyuono, Abdul Halim, Roslan Noorain, Widiyastuti Widiyastuti, Rizna Triana Dewi, Toshiharu Enomae
Formato: article
Lenguaje:EN
Publicado: MDPI AG 2021
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Acceso en línea:https://doaj.org/article/e3b5dda55e954b3c813b24bd8b47b64c
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Sumario:This study explored the tunability of a 3-D porous network in a freeze-dried silk fibroin/soursop seed (SF:SS) polymer composite bioadsorbent. Morphological, physical, electronic, and thermal properties were assessed using scanning electron microscopy, the BET N<sub>2</sub> adsorption-desorption test, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). A control mechanism of pore opening–closing by tuning the SS fraction in SF:SS composite was found. The porous formation is apparently due to the amount of phytic acid as a natural cross-linker in SS. The result reveals that a large pore radius is formed using only 20% wt of SS in the composite, i.e., SF:SS (4:1), and the fibrous network closes the pore when the SS fraction increases up to 50%, i.e., SF:SS (1:1). The SF:SS (4:1) with the best physical and thermal properties shows an average pore diameter of 39.19 nm, specific surface area of 19.47 m<sup>2</sup>·g<sup>−1</sup>, and thermal stability up to ~450 °C. The removal of the organic molecule and the heavy metal was assessed using crystal violet (CV) dye and the Cu<sup>2+</sup> adsorption test, respectively. The adsorption isotherm of both CV and Cu<sup>2+</sup> on SF:SS (4:1) follows the Freundlich model, and the adsorption kinetic of CV follows the pseudo-first-order model. The adsorption test indicates that physisorption dominates the adsorption of either CV or Cu<sup>2+</sup> on the SF:SS composites.