Elimination of 4‐chlorophenol in aqueous solution by the Novel Pd/MIL‐101(Cr)‐Hydrogen‐Accelerated catalytic fenton system

Excessive consumption of Fe (II) and massive generation of sludge containing Fe (III) from classic Fenton process remains a major obstacle for its poor recycling of Fe (III) to Fe (II). Therefore, the MHACF-MIL-101(Cr) system, by introducing H-2, Pd-0 and MIL-101(Cr) into Fenton reaction system, was developed at normal temperature and pressure. In this system, the reduction of Fe-III back to Fe-II by solid catalyst Pd/MIL-101(Cr) for the storage and activation of H-2, was accelerated significantly by above 10-fold and 5-fold controlled with the H-2-MIL-101(Cr) system and H-2-Pd-0 system, respectively. However, the concentration of Fe (II) generated by the reduction of Fe (III) could not be detected with the only input of H-2 and without the addition of MOFs material. In addition, the apparent consumption of Fe (II) in MHACF-MIL-101(Cr) system was half of that in classical Fenton system, while more Fe (II) might be reused infinitely in fact. Accordingly, only trace amount of Fe (II) vs H2O2 concentration was needed and hydroxyl radicals through the detection of para-hydroxybenzoic acid (p-HBA) as the oxidative product of benzoic acid (BA) by center dot OH could be continuously generated for the effective degradation of 4-chlorophenol(4-CP). The effects of initial pH, concentration of 4-CP, dosage of Fe2+, H2O2 and Pd/MIL-101(Cr) catalyst, Pd content and H-2 flow were investigated, combined with systematic controlled experiments. Moreover, the robustness and morphology change of Pd/MIL-101(Cr) were thoroughly analyzed. This study enables better understanding of the H-2-mediated Fenton reaction enhanced by Pd/MIL-101(Cr) and thus, will shed new light on how to accelerate Fe (III)/Fe (II) redox cycle and develop more efficient Fenton system.