Sustainable magnetically recoverable Iridium-coated Fe3O4 nanoparticles for enhanced catalytic reduction of organic pollutants in water

Abstract

In the present study, modi ed Fe 3 O 4 nanoparticles were fabricated by surface coating with tryptophan and Iridium by coprecipitation method to afford Fe 3 O 4 @trp@Ir magnetic nanoparticles. As-prepared Fe 3 O 4 @trp@Ir nanoparticles are environmentally benign e cient catalysts for reducing organic pollutants such as 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), and 1-bromo-4-nitrobenzene (1-B-4-NB). The key parameters that affect the catalytic activity like temperature, catalyst loading, and the concentration of reducing agent NaBH 4 were optimized. The obtained results proved that Fe 3 O 4 @trp@Ir is an e cient catalyst for reducing nitroaromatics at ambient temperature with a minimal catalyst loading of 0.0025%. The complete conversion of 4-nitrophenol to 4-aminophenol took only 20 seconds with a minimal catalyst loading of 0.0025% and a rate constant of 0.0522 s − 1 . The high catalytic activity factor (1.040 s − 1 mg − 1 ) and high turnover frequency (9 min − 1 ) obtained for Fe 3 O 4 @trp@Ir nanocatalyst highlight the possible synergistic effect of the two metals (Fe and Ir). The visible-light photocatalytic degradation of 4-NP was also investigated in the presence of Fe 3 O 4 @trp@Ir. The photocatalytic degradation of 4-NP by Fe 3 O 4 @trp@Ir is completed in 20 min with 95.15% e ciency, and the rate of photodegradation of 4-NP (0.1507 min − 1 ) is about twice the degradation rate of 4-NP in the dark (0.0755 min − 1 ). The catalyst was recycled and reused for ve cycles without signi cant reduction in the conversion e ciency of the catalyst.