Intensified photodegradation of nitrobenzene using ZnO-anchored spinel cobalt ferrite: Environmental application, mechanism, and degradation pathway

• Published in: Journal of water process engineering 2022-10, Vol.49, p.103064, Article 103064
• Main Authors: Ahmadi, Mohammad, Moslemzadeh, Mehrdad, Naderi, Azra, Zehtab Salmasi, Milad, Harati, Motahareh, Rezaei Kalantary, Roshanak, Kakavandi, Babak
• Format: Article
• Language: English
• Subjects: Cobalt ferrite; Heterogeneous photocatalyst; Magnetic ZnO; Nitrobenzene
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2022.103064

Aromatic and cyclic organic compounds such as nitrobenzene (NB) are widely used in various industries and are present in their wastewater. In addition, the photocatalytic process has received considerable attention due to its lower chemical consumption and more efficient degradation of refractory pollutants. In this study, a CoFe2O4-ZnO (CFZ) composite was prepared and evaluated its efficiency in the degradation of NB from aqueous solution under UV light. The optical, structural, and physicochemical properties of catalysts were characterized using PL, UV–vis DRS, XRD, TEM, FESEM-EDS, and VSM techniques and then discussed in detail. It was found that not only does the use of CF facilitate the recovery of pristine ZnO, but it also increases its photocatalytic activity and performance significantly. As compared to single semiconductors, the hybrid CFZ showed the highest efficiency towards NB decontamination, illustrating a strong synergy effect between CF and ZnO. The complete decontamination of NB (30 mg/L) and removal of 85.8 % of TOC were achieved by CFZ/UV system within 60 min reaction time under optimum conditions (pH: 9.0, catalyst dose: 0.4 g/L, and UV light intensity: 4 mW/cm2). CFZ showed excellent stability and reusability test performances with minimal leaching of metal ions. Among the active species, OH radicals played a crucial role in NB degradation. In addition, intermediates during the degradation process were analyzed and identified, and eventually, the possible decomposition pathway of NB was suggested. Furthermore, different possible photocatalytic mechanisms were described to better understand the separation and migration of charge carriers between the semiconductors. As demonstrated in this study, anchoring CF in ZnO can enhance its photocatalytic activity, which could offer promising results in recycling organic contaminants in polluted water. [Display omitted] •S-scheme CFZ heterojunction photocatalyst was prepared and used to degrade NB.•A strong synergy effect was observed between ZnO and CF in coupling with UV towards NB elimination.•100 and 85.8 % efficiencies were attained in the removal of NB and TOC, respectively.•CFZ exhibited good recyclability and stability during five consecutive NB photoreduction cycles.•The degradation rate constant of CFZ/UV was 48, 18.5, 16.6, and 10.5 times greater than UV, CFZ, CF/UV, and ZnO/UV systems, respectively.