Preparation of a new green composite based on chitin biochar and ZnFe2O4 for photo-Fenton degradation of Rhodamine B

With the development of the industry and the increase in the world population, there is also a growing concern about the effect that these factors cause on the environment. Among the pollutants from human activities are the synthetic dyes, which can have toxic and carcinogenic characteristics. Rhodamine B is a red dye used mainly in the textile and food industries. One of the main techniques studied to remove these pollutants from wastewater is the Advanced Oxidative Processes (AOPs) with emphasis on the Heterogeneous Photo-Fenton Process, which consists of the combination of an iron-based photocatalyst, an oxidizing agent and UV-Vis radiation. In the present study, zinc ferrite (ZnFe2O4) was synthesized and supported in different masses of chitin biochar (ZnFO1/B1, ZnFO1/B3, and ZnFO3/B1) and then characterized by FE-SEM, EDS, HR-TEM, FT-IR, XRD, UV-Vis Spectra and Zeta potential, which showed that the support of the ferrite on the biochar surface was properly done. The band gap energies of the prepared composites were narrower than the one of the ferrite alone, which increased their photocatalytic activities. The percentages of Rhodamine B removal were 20%, 85%, 100% and 70% for ZnFe2O4, ZnFO1/B3, ZnFO1/B1, and ZnFO3/B1 respectively, during 60 min of heterogeneous photo-Fenton tests carried under visible light. The ZnFO1/B1 composite was also proven to remain efficient during the recycling tests even after eight cycles of photo-Fenton reactions. The ZnFO1/B1 composite also was able to fully degrade solutions of the same dye at concentrations of 10 and 50 mg L−1 under solar light in 20 and 40 min, respectively. The •OH radicals were determined to be the main reactive species involved in the dye degradation. The proposed composite in this work showed to be a promising material for treatment by photo-Fenton of wastewater contaminated by organic pollutants.