Destruction of 4-chlorophenol by the hydrogen-accelerated catalytic Fenton system enhanced by Pd/NH₂-MIL-101(Cr)

4-chlorophenol (4-CP) could be rapidly mineralized by using Fenton reaction. However, massive iron sludge will be generated because of the excessive consumption of iron salt and poor recycling of Fe^III back to Fe^II. In this paper, by introducing hydrogen gas and solid catalyst Pd/NH₂-MIL-101(Cr) to classic Fenton reactor, the novel system named MHACF-NH₂-MIL-101(Cr) was constructed. Much less Fe^II was needed in this system because the hydrogen could significantly accelerate the regeneration of Fe^II. The catalyst improved the utilization of H₂. The degradation reaction of 4-CP could be driven by using only trace amount of Fe^II. It could be rapidly degraded by the hydroxyl radical detected by the 4-Hydroxy-benzoicacid which is the oxidative product of benzoic acid and hydroxyl radical. The effects of dosage of ferrous salt, H₂O₂ and catalyst, H₂ flow, Pd content, and initial pH of and concentration of 4-CP aqueous solution were investigated. The robustness and morphology changes of this catalytic material were also systematically analysed. By clarifying the role of this solid MOFs material in this hydrogen-mediated Fenton reaction system, it will provide a new direction for the research and development of advanced oxidation processes with high efficiency and low sludge generation in future.