Immobilization of uranium soil with nHAP and composite

Abstract

One of the more concerning issues in the world today is that radioactive uranium contaminates the soil and threatens the organisms. The focus of contaminated soil remediation is to immobilize the uranium in the soil and reduce its leaching. Nano-hydroxyapatite (nHAP) and nano-hydroxyapatite/nano-zero-valent iron mixture (nHAP/nZVI) are used as immobilizer to remediate uranium-contaminated soil. The leaching characteristics and morphological changes of uranium before and after immobilization were studied by using Toxicity Characteristic Leaching Procedure (TCLP) and Tessier stepwise chemical extraction method. The results show that the leaching concentration of uranium in the soil was 0.005 mg/L when nHAP was added alone, and the leaching rate was 9.14%. The leaching concentration of uranium in the soil was only 0.004 mg/L when adding nHAP/nZVI, and the leaching rate was reduced to 8.57%. U (VI) not only reacts with nHAP to form a stable complex but also is reduced by nZVI to insoluble U (IV) when nHAP/nZVI is added. As a result, both nHAP/nZVI and nHAP can effectively immobilize uranium in the soil, and nHAP/nZVI can better promote the immobilization of the uranium in the soil.