Al-Doped magnetite encapsulated in mesoporous carbon: a long-lasting Fenton catalyst for CWPO of phenol in a fixed-bed reactor under mild conditions. Issue 22 (20th October 2021)

• Record Type: Journal Article
• Authors: Thirumoorthy, K.; Gokulakrishnan, B.; Satishkumar, G.; Landau, M. V.; Man, M. Wong Chi; Oliviero, E.
• Is Part Of: Catalysis science & technology. Volume 11:Issue 22(2021)
• Page Start: 7368
• Page End: 7379
• Publication Date: 2021-10-20
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d1cy01218e
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Al substituted magnetite was identified as a promising heterogeneous Fenton catalyst for CWPO of 200 ppm phenol in a continuous system under mild conditions (pH 5, 40 °C, 0.1 ml min −1, 1.2 S H2 O2 ) for 500 h with 80% TOC conversion, 1 ppm Fe leaching. Abstract : Al-Doped magnetite spinel nanoparticles encapsulated in mesoporous carbon (MC) were identified as a promising heterogeneous Fenton catalyst towards phenol degradation in a continuous system for practical applications. Under the working conditions inside the fixed-bed reactor hercynite in the fabricated 21%γ-Fe2 O3 /28%FeAl2 O4 @MC material reacts with H2 O2 . In this reaction Al ions occupied the vacant octahedral cationic sites in the framework of the γ-Fe2 O3 component converting it to Al substituted magnetite spinel. The Al in the obtained Fe 3+ 0.66 Fe 2+ 0.33 (Fe 2+ 0.33 Fe 3+ 0.33 Al 3+ 0.33 )2 O4 @MC polarizes electrons of iron ions through its Lewis acid properties imparting more positive charge on iron ions (Fe n +( δ +) ). This expedites the rate of the challenging reduction reaction Fe 3+ → Fe 2+ with H2 O2 to produce HOO˙ and reinforces the bonding of iron ions in the spinel improving their activity and stability. Hence, under mild operating conditions (pH 5, 40 °C, 8.6 ml water per ml cat h −1, 0.036 mol H2 O2, 200 ppm phenol) the in situ produced catalyst Fe(Fe0.66 Al0.33 )2 O4 @MC of 35 nm containing 19.9%Fe and 2.4%Al with a surface area of 335 m 2 g −1 exhibited long-lasting high catalytic activity and stability during a 500 h run. 80% TOC conversion and ∼1 ppm of leached Fe in treated water were obtained without a visible change of catalytic performance.