Removal of trace radioactive Cs+ by zirconium titanium phosphate: From bench-scale to pilot-scale

Abstract

Removing trace radioactive 137Cs from aquatic system is still a challenge. Herein, Zirconium Titanium Phosphate (ZTP) was prepared and utilized for Cs removal from seawater. The structure and morphology of ZTP were systematically characterized. ZTP exhibited typical feature of tetravalent metal acid, and the surface was pocked with abundant hydroxyl groups which can reacted with H2O to form exchangeable protons. Bench-scale to pilot-scale adsorption was carried out to assess Cs removal capacity and rate. ZTP showed a good adsorption performance for Cs+ especially at trace concentration (500 ppb) and the removal rate in deionized water and seawater were 98.8 % and 83.9 %, respectively. Radioactive experiments were conducted to test the selective removal of 137Cs+ and the removal rates reached 98.3 %. Slurry-bed adsorption device was designed and used as the pilot-scale equipment. The removal rate was as high as 92.7 % after 12 cycles, indicated that ZTP is one of the promising adsorbents in industrial application. Pyridine adsorption IR spectra indicated that surface of ZTP was riddled with Brønsted and Lewis acid sites, and the protons at the Brønsted acid site exchanged with Cs+. This work will provide reference for the treatment of large-scale Cs-contaminated wastewater.