Barium (Ⅱ)-doped zinc ferrite-reduced graphene oxide nanohybrids for superior adsorption and magnetic properties

A one-step solvothermal method was used to prepare barium (Ⅱ)-doped zinc ferrite/reduced graphene oxide (Ba²⁺-ZF/rGO) magnetic nanohybrid adsorbents. During the solvothermal treatment, Ba²⁺-ZF nanoparticles were formed from Ba²⁺, Fe³⁺ and Zn²⁺ chlorides, which were anchored on the surface of rGO obtained from the reduction of GO with ethylene glycol. TEM and SEM results show that the Ba²⁺-ZF nanoparticles are uniformly distributed on the rGO sheets without any agglomeration. When used as adsorbents, the Ba²⁺-ZF/rGO nanohybrid with an rGO content of 35% possesses excellent adsorption capacities for methylene blue at different initial concentrations and the adsorption kinetics can be well-described by the pseudo-second-order kinetic model. The formation of Fe²⁺ from FeCl₃·6H₂O and the doping of Ba²⁺ into the spinel structure dramatically improve the magnetism of the zinc ferrite, which makes the magnetic separability of the nanohybrid outstanding. The Ba²⁺-ZF/rGO nanohybrid could be used as an efficient, magnetically separable adsorbent for removing organic dyes.