Construction of ZIF/CS and ZIF/CS-derivatives with high-efficiency adsorption for dyes/antibiotics and strong microwave absorption performance

Abstract

Bimetallic Zn/Co-ZIF was in situ loaded onto the surface of chitosan (CS) to form ZIF/CS composites with high-efficiency adsorption of antibiotics (tetracycline (TC)) and dyes (Congo Red (CR), Malachite Green (MG)). The particle size and surface roughness of Zn/Co-ZIF can be effectively adjusted by changing the mass ratio of Zn and Co in ZIF, which helps to regulate the adsorption active sites on the surface of the composites. Meanwhile, the introduction of CS changes the pore structure of the composites, making the molecules of TC, CR and MG easily enter into the pores of ZIF/CS. When the mass ratio of Zn to Co is 1:1, the ZIF/CS composite has the optimal adsorption performance with the ultra-high adsorption capacity qm of 781.3, 1644.2 and 3243.6 mg g−1 for TC, CR and MG, respectively. Impressively, the ZIF/CS-derivative (ZC3–700) from sample ZC3 after calcination at 700 °C under N2 atmosphere owns a good conductive network, which results in its superior microwave absorption performance. Herein, at 30 wt% filler loading, the effective absorption bandwidth and RLmin of ZC3–700 reach 5.28 GHz at 1.90 mm and −68.92 dB at 1.83 mm, respectively. Analyses on microwave absorption mechanism point out the synergistic effect of conduction loss, dipolar polarization and interfacial polarization and magnetic loss on the attenuation of electromagnetic wave. Therefore, ZIF/CS composites and ZIF/CS-derivatives exhibit superior performance on the removal of water pollutants and the absorption of electromagnetic wave, which essentially reveals a multifunctional application of the ZIF/CS composites in the field of environmental protect.