Time and Nanoparticle Concentration Affect the Extractability of Cu from CuO NP-Amended Soil

• Published in: Environmental science & technology Vol. 51; no. 4; pp. 2226 - 2234
• Main Authors: Gao, Xiaoyu, Spielman-Sun, Eleanor, Rodrigues, Sónia M, Casman, Elizabeth A, Lowry, Gregory V
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 21-02-2017
• Subjects: Copper; Copper - chemistry; Dissolution; Kinetics; Nanoparticles; Soil - chemistry; Soils; Time
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.6b04705

We assess the effect of CuO nanoparticle (NP) concentration and soil aging time on the extractability of Cu from a standard sandy soil (Lufa 2.1). The soil was dosed with CuO NPs or Cu­(NO3)­2 at 10 mg/kg or 100 mg/kg of total added Cu, and then extracted using either 0.01 M CaCl2 or 0.005 M diethylenetriaminepentaacetic acid (DTPA) (pH 7.6) extraction fluid at selected times over 31 days. For the high dose of CuO NPs, the amount of DTPA-extractable Cu in soil increased from 3 wt % immediately after mixing to 38 wt % after 31 days. In contrast, the extractability of Cu­(NO3)2 was highest initially, decreasing with time. The increase in extractability was attributed to dissolution of CuO NPs in the soil. This was confirmed with synchrotron X-ray absorption near edge structure measurements. The CuO NP dissolution kinetics were modeled by a first-order dissolution model. Our findings indicate that dissolution, concentration, and aging time are important factors that influence Cu extractability in CuO NP-amended soil and suggest that a time-dependent series of extractions could be developed as a functional assay to determine the dissolution rate constant.