Copper Speciation in Aquatic Plants by Energy-Dispersive Inelastic X-ray Scattering with X-ray Tube Excitation

V. SBARATO; J. J. LEANI; H. J. SÁNCHEZ; R.D. PÉREZ

Brudge

Conferencia; EXRS 2022; 2022

Energy-Dispersive Inelastic X-ray Scattering (EDIXS) refers to a spectrometric technique thatmakes use of the intrinsic properties of atomic processes at core level involving resonantphotons [1]. This is the case of Resonant Inelastic X-ray Scattering (RIXS) which, incombination with the experimental advantages of an energy dispersive setup (EDS) andmultivariate methods for data analysis allows for obtaining characterization of chemicalenvironments in diverse samples and experimental conditions.This work presents an application of EDIXS using a conventional x-ray tube as source, forchemical state discrimination of metal in environmental samples of phytoremediation.Phytoremediation technology is used for the treatment of polluted streams and wastewaterscontaminated with metals. It is relevant to differentiate between the oxidation states of metalsin plants to understand the predominant removal mechanisms and make decisions thatcontribute to its recovery [2]. The preliminary setup employed for this experience wascomposed by an x-ray tube, a Si(111) crystal monochromator, a couple of slits, a versatilesample holder and a Si-pin diode x-ray detector.The studied samples were aquatic plants exposed at a SO4Cu water solution of highconcentration (20 ppm). RIXS spectra of each sample were acquired using an incident beamenergy below but close to the Cu-K edge. RIXS peaks were then analyzed by a multivariatemethod in order to properly discriminate the fine structure of each spectrum. The coppercomposites present in roots and shoots showed different chemical states. While copper inroots had a well defined chemical state different than SO4Cu, shoots presented a mixture ofcopper species. It agrees with the idea that roots processes the copper while shoots receivecopper species from the roots and also from the SO4Cu water solution by adsorption [2]. Theresults 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 structuralcharacterizations of environmental samples by means of EDIXS using a simple energydispersive setup combined with a conventional x-ray tube.