Modified Chitosan\nNanofiber Membrane Fabrication for\nRemoval of Pb<sup>2+</sup> from Coptidis rhizoma Decoction

Heavy metals in medicine are easily introduced during\nproduction\nand processing, and heavy metals pose a risk to human health. To realize\nthe separation of heavy metals from medicine and provide a new method\nfor removing heavy metals, in this study, ethylenediaminetetraacetic\nacid (EDTA) was used to modify chitosan, and the ethylenediaminetetraacetic\nacid-modified chitosan (CS-EDTA) fiber membrane was prepared through\nelectrospinning to remove lead ions from Coptidis rhizoma decoction. The effects of spinning speed (0.1 mL/h), modification\nmethod (2 g Na<sub>2</sub>EDTA, 0.1 g EDC, 0.2 g NHS), and pH (pH\n= 5) on the adsorption capacity were studied. The results showed that\nthe adsorption of Pb<sup>2+</sup> on the CS-EDTA membrane was pseudo-second-order\nkinetics model (<i>R</i><sup>2</sup> > 0.999) and the\nLangmuir\nmodel (<i>R</i><sup>2</sup> > 0.978). The <i>kinetic</i> maximum adsorption capacity of the CS-EDTA membrane was 116.2 mg·g<sup>–1</sup>. The Pb<sup>2+</sup> content in C.\nrhizoma decoction after adsorption meets the limit\nrequirements for heavy metals specified in the traditional Chinese\nmedicine standard (Pb<sup>2+</sup> ≤ 5 mg·kg<sup>–1</sup>). The chemical composition of the decoction of C.\nrhizoma did not change significantly after the removal\nof Pb<sup>2+</sup>. The membrane has antibacterial properties against\nGram-negative bacteria.