Copper speciation in aquatic plants by RIXS with x-ray tube excitation

V. SBARATO; JUAN JOSÉ LEANI; HÉCTOR SÁNCHEZ; PEREZ, DANIEL ROBERTO

Brujas

Conferencia; The European Conference on X-Ray Spectrometry (EXRS); 2022

University of Antwerp

Energy-Dispersive Inelastic X-ray Scattering (EDIXS) refers to a spectrometric technique that makes use of the intrinsic properties of atomic processes at core level involving resonant photons [1]. This is the case of Resonant Inelastic X-ray Scattering (RIXS) which, in combination with the experimental advantages of an energy dispersive setup (EDS) and multivariate methods for data analysis allows for obtaining characterization of chemical environments in diverse samples and experimental conditions.This work presents an application of EDIXS using a conventional x-ray tube as source, for chemical state discrimination of metal in environmental samples of phytoremediation. Phytoremediation technology is used for the treatment of polluted streams and wastewaters contaminated with metals. It is relevant to differentiate between the oxidation states of metals in plants to understand the predominant removal mechanisms and make decisions that contribute to its recovery [2]. The preliminary setup employed for this experience was composed by an x-ray tube, a Si(111) crystal monochromator, a couple of slits, a versatile sample holder and a Si-pin diode x-ray detector.The studied samples were aquatic plants exposed at a SO4Cu water solution of high concentration (20 ppm). RIXS spectra of each sample were acquired using an incident beam energy below but close to the Cu-K edge. RIXS peaks were then analyzed by a multivariate method in order to properly discriminate the fine structure of each spectrum. The copper composites present in roots and shoots showed different chemical states. While copper in roots had a well defined chemical state different than SO4Cu, shoots presented a mixture of copper species. It agrees with the idea that roots processes the copper while shoots receive copper species from the roots and also from the SO4Cu water solution by adsorption [2]. The results show that the fine structure of each RIXS peak clearly depends on the studied sample, i.e., the chemical state of copper. This outcome opens the possibility of local structural characterizations of environmental samples by means of EDIXS using a simple energy dispersive setup combined with a conventional x-ray tube.