Monitoring of copper phytofiltration performance by x-ray analytical techniques

V.M. SBARATO; J.J. LEANI; E. MÜLLER; R.D. PEREZ; D.A. RIEGO

Congreso; 2nd Groundwater Remediation using Nano/biotechnology with focus on the Contaminated Resources in Brazil; 2021

Brazilian Center for Research in Energy and Materials (CNPEM)

In this work, micro-XRF was considered as a possible technique for monitoring the rate of incorporation of Cu into aquatic plants of a laboratory-scale phytofiltration system. This system employed Salvinia Biloba Raddi under controlled conditions of light and nutrients. This aquatic plant is being considered as an efficient hiperaccumulator of Cu and is widely spread in South American lakes and rivers. A set of 30 plants was exposed at 40 ppm w/w of Cu for 6 days. The analytical procedure was based on the periodic in vivo quantitative analysis of Cu at selected points in the plants using micro-XRF. For the measurements, a dedicated spectrometer for micro-XRF analysis that focalize Mo X-ray tube emission with a capillary optic was employed. The accuracy in elemental quantification was effectively improved with the assistance of the Monte Carlo XMI-MSIM simulation code [1]. The precise results demonstrated that the proposed methodology is able to provide an efficient indicator of the moment since the plants become saturated. This indicator is essential for deciding when plants should be harvested and replaced to improve the metal removal capacity of the phytofiltration system. The knowledge of the chemical state of copper is highly valuable to decide the final destiny of harvested plants. This work presents an application of Energy-Dispersive Inelastic X-ray scattering (EDIXS) using a conventional x-ray tube as the source, for chemical state discrimination of copper in the harvested plants [2]. Several EDIXS spectra of five samples were acquired using an incident beam with energy below the Cu-K edge. EDIXS peaks were then studied by principal component analysis in order to properly discriminate the fine structure of each spectrum. The results showed that copper in roots and leaves had different chemical valence supporting that EDIXS could be a way to differentiate between bioadsorption and bioaccumulation.