Effective photocatalytic degradation of rhodamine B dye by nickel ferrite/(N,S)graphene oxide

Nickel ferrite/(N,S)graphene oxide (NF/(N,S)GO) was synthesized by a facile coprecipitation-hydrothermal route using Ni2+ and Fe3+ mixture in (N,S)GO suspension. This material was used as a photocatalyst for the degradation of rhodamine B (RhB) as a dye model in aquatic environment. It was found that NiFe2O4 nanoparticles with a particle size of 11.5 nm was highly dispersed on (N,S)GO matrix, which was prepared from graphite and thiourea. Visible-light-induced photodegradation of RhB over NF/(N,S)GO has been studied where NF/(N,S)GO presented high photodegradation activity toward RhB compared to both nickel ferrite and (N,S)GO. Furthermore, after three cycles of photodegradation of RhB, the catalyst did not exhibit significant loss of activity (with a drop of around 15% in degradation efficiency compared to fresh catalyst), confirming its stability. The chemical oxygen demand (COD) measurement revealed a gradual decrease of COD from 49.4 mg.L−1 at initial time to 4.8 mg.L−1 after 240 min of light illumination, indicating high degree of mineralization of the degradation process. In addition, kinetic and radical scavenger studies suggest that superoxide ions (·O2−), hydroxyl ions (·OH) were the dominant photooxidants, followed by hole (h+) and electron (e−). The degradation mechanism of RhB over NF/(N,S)GO was also addressed. This study provided a possible treatment approach for organic pollutants in aqueous solution by exploiting visible light source.