Acceleration of FeIII/FeII cycle enhanced by Pd/MOF-808(Zr) composite in hydrogen promotion Fenton system for sulfamethazine elimination

Under normal temperature and pressure, a novel improved Fenton system that was named MHACF-MOF-808(Zr) was constructed after the introduction of Pd/MOF-808(Zr) and H 2 to solve the inherent problem of the production of iron sludge in the classic Fenton system. Only trace amount of Fe II was required during the whole reaction because Fe III could be rapidly reduced by the active hydrogen derived from the adsorption and activation of H 2 on the surface of Pd/MOF-808(Zr) composite. The concentration of Fe II could be maintained more than 10 μM. The removal of target pollutant sulfamethazine in this system was mainly relied on the degradation of ·OH verified by both of the direct detection and indirect inhibition (using methanol). By using the calculation of Laplacian bond order, the degradation pathway of sulfamethazine followed by the cleavage of N  S bond. This prediction was verified by the detection of intermediate products. Only 21% sulfamethazine could be degraded after 3-h reaction in the classic Fenton reaction system, while it could be thoroughly degraded in 1.5 h in the MHACF-MOF-808(Zr) system. The influence of main parameters on the degradation effect of sulfamethazine, such as initial pH, the flow of H 2 , dosage of Pd/MOF-808(Zr), concentration of sulfamethazine, ferrous, and hydrogen peroxide, were systematically studied. Based on the relative stability of Pd/MOF-808(Zr) confirmed by the morphological characterization, sulfamethazine could be efficiently degraded in the MHACF-MOF-808(Zr) system.