SuFEx modification of silk fibroin silicon aerogel and its adsorption behavior and antibacterial performance

A silk fibroin silicon-based composite aerogel (SSA) has been modified via a SuFEx reaction for application in the adsorption of anionic pollutants and antimicrobials in water. The tyrosine fragment in the silk fibroin was modified by a high yielding SuFEx click reaction. A quaternary ammonium salt functionality was introduced into the silk fibroin protein and the modified silk fibroin protein was crosslinked with tetraethyl orthosilicate. The aerogel was then prepared by freeze-drying. The aerogel obtained has biocompatibility and biodegradability properties. Four types of dyes (Methyl orange, Rhodamine B, Methylene blue and Acid red) were applied as targets and the saturated adsorption amounts were calculated. The adsorption behavior of the dyes towards SSA was studied by fitting Langmuir and Freundlich adsorption models. A pseudo-first order kinetic model and a pseudo-second order kinetic model were used to study the kinetics of the adsorption process. After 6 cycles, the removal rate of methyl orange by SSA remained at 81.25%. The adsorption capacity and anti-interference ability of SSA on some other polluting anions such as PO₄^3- and CrO₄^2- were also measured and the efficiency adsorption reached up to 70.94% and 77.91%, respectively. The antibacterial effect of SSA was evaluated with Escherichia coli and Staphylococcus aureus as representative examples.