Nitrilotriacetic acid modified magnetic Prussian blue for efficient removal of cadmium from wastewater

Novel and environmentally-friendly magnetic adsorbent (Fe3O4@PB@NTA) was prepared for the removal of cadmium (Cd2+) from wastewater. The magnetic Prussian blue (Fe3O4@PB) was synthesized by hydrochloric acid etching method, so that Prussian blue was grown on the surface of Fe3O4. Then, nitrilotriacetic acid (NTA) was used as a chelating agent for surface modification of Fe3O4@PB. The successful loading of NTA was confirmed by structural characterizations such as FTIR, TGA, BET, etc. The adsorption isotherm model analysis was consistent with the Langmuir model, and the maximum adsorption capacity of Fe3O4@PB@NTA for Cd2+ was 310.56 mg/g. Fe3O4@PB@NTA has excellent regeneration and reusable performance, the removal rate of Cd2+ still reached by 93.12% after 5 times of regeneration. According to FTIR and XPS analysis, partial-C equivalent to N of Prussian blue might be hydrolyzed to the amide groups. The adsorption mechanism involved the formation of N-Cd coordination bonds by sharing electron pairs due to the presence of O=C-NH and-C equivalent to N on the Fe3O4@PB@NTA, and the C=O provided by nitrilotriacetic acid could combine with Cd to form the O-Cd complex compound, the electrostatic attraction between COO- and Cd2+ also existed. Therefore, Fe3O4@PB@NTA is a promising adsorbent for the treatment of cadmium-containing wastewater.

Automated summary

A novel and environmentally-friendly magnetic adsorbent (Fe3O4@PB@NTA) was developed for the removal of cadmium from wastewater. The adsorbent showed excellent adsorption capacity and regeneration performance, and the adsorption mechanism was found to involve the formation of coordination bonds and electrostatic attraction.