Conversion of lanthanum and cerium recovered from hazardous waste polishing powders to hazardous ammonia decomposition catalysts

Bing-Sheng Yu; Jun-Lun Jiang; Chu-Chun Yang

doi:10.1016/j.jhazmat.2019.120773

Conversion of lanthanum and cerium recovered from hazardous waste polishing powders to hazardous ammonia decomposition catalysts

J Hazard Mater. 2019 Nov 5:379:120773. doi: 10.1016/j.jhazmat.2019.120773. Epub 2019 Jun 13.

Authors

Bing-Sheng Yu¹, Jun-Lun Jiang², Chu-Chun Yang²

Affiliations

¹ Institute of Mineral Resources Engineering, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Road, Taipei, Taiwan. Electronic address: bing@ntut.edu.tw.
² Institute of Mineral Resources Engineering, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Road, Taipei, Taiwan.

PMID: 31271939
DOI: 10.1016/j.jhazmat.2019.120773

Abstract

The polishing process in high-tech industries produces a large amount of waste polishing slurry, which is harmful to the environment, and the solid powders in the slurry contain a lot of La and Ce, which have been widely used as catalyst materials. The aim of this study was to convert this hazardous material into hazardous material decomposition catalyst. A novel and simple approach was successfully developed for the recovery of La and Ce from hazardous waste polishing powders to synthesize a composite metal oxide catalyst for decomposition of harmful ammonia. Here, La and Ce were leached from waste polishing powder by using nitric acid, and the Ce, La, and total REE recovery rates were approximately 100%, 83.3%, and 96.4%, respectively. The elemental concentrations of leached acidic solution was analyzed, after which stoichiometry was performed to replenish elements with insufficient mole numbers. Finally, the catalyst material was prepared using the glycine-nitrate combustion process. The catalyst prepared from the recovered polishing powders achieved a 100% ammonia conversion rate at the relatively low temperature of 250 °C. The proposed environmentally friendly method does not require complex purification and separation procedures and can be used for the synthesis of catalysts for decomposing other harmful pollutants.

Keywords: Glycine-Nitrate combustion process (GNP); Hazardous substance decomposition catalyst; Rare earth elements recycling; Waste polishing powders.