کاتالیزور فنتون مانند کاربردی و قابل بازیافت
Abstract
Graphical abstract
1. Introduction
2. Materials and methods
3. Results and discussion
4. Conclusions
Acknowledgements
Appendix A. Supplementary data
References
Abstract
A thin disc-shaped Fenton-like catalyst sized 28.59*1.39 mm in diameter and thickness was produced by ball milling a hemi-dried silica xerogel with iron (III) acetylacetonate, followed by mold pressing and calcination. The developed compact catalyst facilitated its application and recovery. The whole fabrication process was free of wastewater emission. Plasticizers or binders indispensable for shaping commercial powders into compact green bodies were not necessary in the present method. The bulky catalyst was mesoporous and had a large surface area of 580 m2 /g, providing access to the activation of H2O2 by the active iron sites inside the sample. It removed 100% of methylene blue (MB) in solution with a total TOC reduction by 92.13% mainly via the Fenton degradation. No washing, chemical elution of the adsorbed dye before the next application was applied. After five cycles, ca.93% of the removal efficiency was maintained. The TOC reduction increased from the 1st to 3rd cycle and ca.88% of the initial capacity was kept after the 5th cycle, while the iron leaching was only 0.021% of the applied catalyst. The excellent performance of the bulky catalyst was due to its large surface area, uniformly distributed and chemically bonded iron species. The present work provides a scalable and green way to produce Fenton-like catalysts for environmental application.
Introduction
Dyes are used in industries including textile, leather manufacturing and printing, etc., leading to the formation of wastewaters containing dye molecules. Most synthetic dyes are difficult to degrade and have detrimental environment effects (Holkar et al., 2016). Using Fenton (-like) catalysts is an effective way to remove the dyes from wastewaters via degradation. It mainly utilizes iron-containing catalysts reacting with H2O2 to form free radicals as oxidants for the degradation of organic pollutants to carbon dioxide and water or to small molecules (Zhang et al., 2016; Li et al., 2019). Many different types of Fenton-like catalysts have been developed and applied in wastewater treatment (Nidheesh, 2015). Ironcontaining silica-based porous composites are among the developed Fenton-like catalysts which exhibited good dye removal performance. They were mostly prepared via hydrothermal reaction (Meng et al., 2016), sol-gel method (Chae et al., 2016) or impregnation (Ursachi et al., 2012; Rostamizadeh et al., 2018). These methods face a great challenge due to the emission of wastewater during the production of catalysts. Some of the Fenton-like catalysts have been proved efficient in removing methylene blue (MB), a commonly used dye in industries, from wastewaters (Zhang et al., 2016; Chai et al., 2016; Li et al., 2017; Mohamed et al., 2017; Li et al., 2018; Li et al., 2018; Li et al., 2018; He et al., 2018; Hu et al., 2019). However, with few exceptions (Li et al., 2018; Shi et al., 2019), most of such catalysts so far are in powder form, which makes their dispersion in wastewater and the recovery after the application a difficult work. In addition, the collection of used catalysts via filtration or centrifugation which are normally used in labs is actually not applicable at industrial scale, because of the small dosage of powders added in wastewaters.