Highly effective bromate reduction by liquid phase catalytic hydrogenation over Pd catalysts supported on core-shell structured magnetites: Impact of shell properties

Minghui Li; Xiaomei Zhou; Jingya Sun; Heyun Fu; Xiaolei Qu; Zhaoyi Xu; Shourong Zheng

doi:10.1016/j.scitotenv.2019.01.392

Highly effective bromate reduction by liquid phase catalytic hydrogenation over Pd catalysts supported on core-shell structured magnetites: Impact of shell properties

Sci Total Environ. 2019 May 1:663:673-685. doi: 10.1016/j.scitotenv.2019.01.392. Epub 2019 Jan 31.

Authors

Minghui Li¹, Xiaomei Zhou¹, Jingya Sun¹, Heyun Fu¹, Xiaolei Qu¹, Zhaoyi Xu¹, Shourong Zheng²

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023, PR China.
² State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023, PR China. Electronic address: srzheng@nju.edu.cn.

PMID: 30731413
DOI: 10.1016/j.scitotenv.2019.01.392

Abstract

Liquid phase catalytic reduction of bromate with supported noble metals as the catalysts is a promising method to remove bromate in water. Magnetic supports provide a feasible way to recover catalysts whose surface properties also strongly influence the catalytic efficiency. In this study, Pd nanoparticles supported on core-shell structured magnetites with varied shells (e.g., carbon, SiO₂, polypyrrole, polyaniline, polydopamine and chitosan) were prepared and catalytic reduction of bromate on the catalysts was investigated. The results showed that in comparison with other catalysts Pd/(Fe₃O₄@polyaniline) exhibited a higher catalytic efficiency due to its higher point of zero charge and surface hydrophilicity. In parallel, bromate reduction on Pd/(Fe₃O₄@polyaniline) followed the Langmuir-Hinshelwood model, confirming the crucial role of bromate adsorption. At pH 5.6 and a catalyst dosage of 0.05 g/L, 0.4 mM bromate could be completely reduced into bromide within 120 min. Furthermore, the magnetic catalysts could be effectively separated and recovered under an external magnetic field within 3 min. The results of catalyst reuse showed that after five consecutive catalytic reduction cycles Pd/(Fe₃O₄@polyaniline) retained 87% of its fresh catalyst activity. The present findings indicate that Pd/(Fe₃O₄@polyaniline) with polyaniline as the shell is a highly active, stable and recyclable catalyst for liquid phase catalytic hydrogenation of pollutants in water.

Keywords: Bromate reduction; Core-shell structure; Liquid phase catalytic hydrogenation; Magnetic catalysts.