Heterogeneous photo-Fenton decolorization of Orange II over Al-pillared Fe-smectite: Response surface approach, degradation pathway, and toxicity evaluation

• Published in: Journal of hazardous materials 2015-04, Vol.287, p.32-41
• Main Authors: Li, Huiyuan, Li, Yanli, Xiang, Luojing, Huang, Qianqian, Qiu, Juanjuan, Zhang, Hui, Sivaiah, Matte Venkata, Baron, Fabien, Barrault, Joel, Petit, Sabine, Valange, Sabine
• Format: Article
• Language: English
• Subjects: Al-pillared Fe-smectite; Aluminum Oxide - chemistry; Animals; Azo Compounds - chemistry; Azo Compounds - radiation effects; Azo Compounds - toxicity; Benzenesulfonates - chemistry; Benzenesulfonates - radiation effects; Benzenesulfonates - toxicity; Catalysis; Catalysts; Chemical Sciences; Daphnia; Daphnia magna; Decoloring; Degradation; Degradation pathway; Heterogeneous photo-Fenton; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Iron - chemistry; Mass spectrometry; Orange II; Oxidation-Reduction; Response surface methodology; Response surfaces; Silicates - chemical synthesis; Toxicity; Toxicity Tests; Ultraviolet Rays; X-Ray Diffraction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.01.023

•Al-pillared Fe-smectite was synthesized and used as the photo-Fenton catalyst.•Response surface methodology was used to study the effects of reaction parameters.•The main intermediate products were identified by GC–MS technique.•A possible degradation pathway of Orange II was proposed.•All the generated products of Orange II were less toxic than the original dye. A ferric smectite clay material was synthesized and further intercalated with Al2O3 pillars for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the photo-Fenton decolorization of azo dye Orange II. UV irradiation was found to enhance the activity of the catalyst in the heterogeneous photo-Fenton process. Catalyst loading of 0.5g/L and hydrogen peroxide concentration of 13.5mM yielded a remarkable color removal, accompanied by excellent catalyst stability. The decolorization of Orange II followed the pseudo-first-order kinetics for initial dye concentrations from 20 to 160mg/L. The central composite design (CCD) based on the response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely initial pH, catalyst loading and hydrogen peroxide concentration, on the decolorization efficiency. The RSM model was derived and the response surface plots were developed based on the results. Moreover, the main intermediate products were separated and identified using gas chromatography–mass spectrometry (GC–MS) and a possible degradation pathway was proposed accordingly. The acute toxicity experiments illustrated that the Daphniamagna immobilization rate continuously decreased during 150min reaction, indicating that the effluent was suitable for sequential biological treatment.