Catalytic hydrodechlorination and advanced oxidation processes of 2,4-dichlorophenoxyacetic acid over CMK-3 supported catalyst: The bi-functional effect of metal Pd

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 402; p. 126175
• Main Authors: Zhou, Xin, Luo, Haopeng, Chen, Quanyuan, Cao, Xin, Shen, Chensi, Zhou, Juan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2020
• Subjects: 2,4-D; AOPs; Combined HDC-AOPs; HDC; Pd/CMK-3; Pd/CMK-3; 2,4-D; HDC; Combined HDC-AOPs; AOPs
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.126175

The Pd/CMK-3 catalyst reflected a good advanced oxidation ability based on PMS activation in situ after the highly effective catalytic hydrodechlorination of 2,4-D. [Display omitted] •The HDC, AOPs and combined HDC-AOPs of 2,4-D were conducted over Pd/CMK-3.•Active Pd species exhibited distinct effects in the HDC and AOPs.•HDC product could be further degraded in the presence of PMS in situ.•Surface-bound free radicals contributed most to the AOPs of 2,4-D.•Metal Pd was more stable after HDC than that of AOPs. The eliminate of 2,4-dichlorophenoxyacetic acid (2,4-D) was achieved via individual and combination of catalytic hydrodechlorination (HDC) and AOPs involved peroxymonosulfate activation. The CMK-3 supported monometallic Pd catalysts with varied Pd loadings were prepared and applied in the reactions. The results showed that Pd/CMK-3 were highly active and competitive in both the HDC and AOPs of 2,4-D, and the removal efficiencies were 91.6 and 95.2% over Pd3/CMK-3 respectively after reaction for 90 min. The dechlorination of 2,4-D was completed via both the stepwise and concerted pathways while the reactant experienced free radical oxidation processes in the AOPs. For the combined HDC-AOPs reaction, Pd/CMK-3 reflected a good advanced oxidation ability after the effective HDC of 2,4-D. Additionally, the catalysts exhibited higher Pdn+/Pd0 ratios after reactions and metal Pd was more stable after the reductive dechlorination than that of advanced oxidation.