Copper(II)-Silk Fibroin Complex Fibers as Air-Purifying Materials for Removing Ammonia

Abstract

To remove ammonia, traditional activated carbon is not as effective as expected. In this paper, a new alternative method of removing ammonia with metal-silk fibroin complex fibers through a coordination displacement reaction is proposed and studied. Electron spin resonance spectra (ESR) and atomic absorption spectrometry show that the Cu(O)₄ complex with low copper(II) content is formed when silk fibroin is soaked in cupric aqueous solution under acid condition, while the structure of the Cu(N)₄ complex with high copper(II) content is formed in a cuprammonia solution. Experimental results further show that the Cu(O)₄ complex is more effective than the Cu(N)₄ complex in term of ammonia adsorption. It is highly desirable to prepare a deodorizing material that has both high copper(II) content and a Cu(O)₄ complex structure. Based on our study, a novel deodorizing fiber is prepared as follows: silk fibroin fibers are first treated with tannic acid (TA), then dipped into the cuprammonia solution to obtain the Cu(O)₄ complex containing 8.5% (wt%) copper(II). Such fibers show high deodorizing performance and can be regenerated by heating.

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