Abstract
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 N2 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 m2·g−1, 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 Cu2+ adsorption test, respectively. The adsorption isotherm of both CV and Cu2+ 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 Cu2+ on the SF:SS composites.
Highlights
There are large numbers of heavy metals, dyes, organic solvents, gasoline oil, salts, hydrocarbons, and other toxic chemical substances associated with industrial waste
Various 3-D porous structures of silk fibroin/soursop seed (SF:SS) biocomposite adadsorbent were successfully prepared by the freeze-drying method using a natural crosssorbent were successfully prepared by the freeze-drying method using a natural crosslinker of phytic acids available in the SS powder
The characterization results show that the linker of phytic acids available in the SS powder
Summary
There are large numbers of heavy metals, dyes, organic solvents, gasoline oil, salts, hydrocarbons, and other toxic chemical substances associated with industrial waste. These contaminants have significant potential to either directly or indirectly pollute surface water. Among various available wastewater treatments, adsorption is considered the most promising method to remove dyes and heavy metals [1]. Over the years, activated carbon has been the most utilized adsorbent throughout the world. Activated carbon suffers from several drawbacks, including high cost, complex separation process, and difficulty of regeneration, which restrict its usefulness in water treatment [2]. In recent years, increasing attention has been
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