Fabrication of iron-dipicolinamide catalyst with Fe–N bonds for enhancing non-radical reactive species under alkaline Fenton process

• Published in: Chemosphere (Oxford) 2020-02, Vol.241, p.125005-125005, Article 125005
• Main Authors: Jin, Qianqian, Chen, Qian, Kang, Jing, Shen, Jimin, Guo, Fang, Chen, Zhonglin
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic performance; Chlorophenols - chemistry; Chlorophenols - isolation & purification; Degradation mechanism; H2O2 activation; Hydrogen Peroxide - chemistry; Iron - chemistry; Iron dipicolinamide; Nitrogen - chemistry; Non-radical species; Oxidants - chemistry; Oxidation-Reduction; Water Pollutants - chemistry; Water Pollutants - isolation & purification
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.125005

Iron dipicolinamide (Fedpa), as an efficient Fenton-like catalyst, was fabricated to excite hydrogen peroxide (H2O2) for the removal of 2,4-dichlorophenol (2,4-DCP). The unique structures and the electronic properties of Fedpa were contributed to its excellent catalytic performance in alkaline Fenton process. Fe was chelated with dpa by four Fe–N bonds leaved two labile sites, which reduced the oxidation potential of dpa[FeIII/FeII], dpa[FeV/FeIII] or dpa[FeIV/FeII] to 0.316 V and 1.189 V respectively, and made it easily be bound with H2O2 to initiate the reaction. The results showed that 99.5% removal rate of 2,4-DCP (0.58 mM) was achieved by using 0.027 g/L Fedpa and 5.8 mM H2O2 in 60 min at pH 9.9. The coordination between Fe and dpa enhanced the catalytic efficiency of FeII. The active species generated in Fedpa/H2O2 system contained the iron-oxo species (dpaFeV = O or dpaIV = O), O2− and HO. The iron-oxo species was the main non-radical reactive species for the degradation of 2,4-DCP and some degradation intermediates were detected by GC-QTOF. Furthermore, the influence of factors, such as Fedpa loading, solution pH, temperature and anions (F−, Cl−, SO42−, NO3− and PO43−) on the catalytic performance of Fedpa were also discussed. This process of complexation between Fe and dpa combined with a green oxidant H2O2 presents a new insight for the use of Fenton-like system in the degradation of refractory organics. [Display omitted] •Fedpa with four Fe–N bonds was an efficient Fenton-like catalyst.•The removal rate of 2,4-DCP and TOC were 99.5% and 90%.•Dpa reduced the oxidation potential of Fedpa to improve Fe activity.•Iron-oxo species replaced radical species as the main reactive species.•Degradation intermediates of 2,4-DCP were identified by GC-QTOF.