LAUSR

In this work, two types of magnetic nanocomposites were synthesized via one-step calcinations of hollow Co-based and Zn/Co-based ZIFs, as well as applied as absorbents in the reduction of Rhodamine B (RhB). Calcination of the Co-ZIF (ZIF-67) produced a simple Co-carbon composite (Co@C), while Zn/Co-ZIF (ZIF-67@ZIF-8) produced a Zn/Co-carbon composite (Zn/Co@C). The prepared composites were carefully analyzed by using SEM, TEM-EDS, XRD, SQUID magnetometer, and Nitrogen adsorption/desorption measurements. Zn/Co@C with a high surface area is desirable for adsorbent reactions, Co@C and Zn/Co@C showed the maximum adsorption capacities of 48 mg g-1 and 101.93 mg g-1 toward RhB. The adsorption isotherms of RhB on Zn/Co@C nanocomposite were well fitted with the Langmuir model and the pseudo-second-order model accurately describes the adsorption kinetic process for the adsorption of RhB on the materials. The results show that the composite materials of Zn/Co@C possess higher porosity and magnetic property and exhibit higher adsorption capacity, convenient separation ability, along with good reusability of the adsorbent. The theoretical calculations also clarify that RhB on distorted Co-Zn surface is much more stable than Co(111), in good agreement with the experimental observations.