Re: [Ifeffit] P K-edge XANES spectrum question

I recommend diluting this sample by a lot (20x maybe, or more) and collecting another spectrum. I've had instances of strange features in P spectra that ended up being weird self-absorption type artifacts. I will dig through the spectra I have from similar samples, this one reminds me of a spectrum I saw once, perhaps in a similar system...It would be interesting if we inadvertently got similar results. Thanks for sharing! Mike

On Oct 16, 2020, at 10:22 PM, Dean Hesterberg wrote:

 Hello Ganga,

That is a very interesting spectrum. Given what you said about the system, the lower energy feature at ~ 2146 eV should be Fe(III)-bonded phosphate and the feature at ~2149 eV should be Al(III)-bonded phosphate. Both produce pre-white line absorption peaks, but the Al-bonded phosphate peak is closer to the white line and less distinct in spectra of Al-phosphates like variscite and non-crystalline Al-phosphate, for example (see Khare et al. 2007. Geochimica et Cosmochimica Acta 71:4405, Fig. 5C). A significant proportion of the phosphate in your system apparently precipitated with Al-13 polymer structures in the aluminum chlorohydrate.

Dean

...

On Fri, Oct 16, 2020 at 1:26 AM Ganga Hettiarachchi wrote: All,

Can anyone provide some insight into the pre-edge “features” in this P XANES spectrum?

This is the P XANES spectrum we got for a recovered P-product (rich in Fe and Al) from wastewater using the AnMBR technology. During the coagulation process, our collaborators (environmental engineers) used stock solutions of aluminum chlorohydrate (ACH) and FeCl3.

Thanks very much.

Best regards,

Ganga

--------------------

Ganga M. Hettiarachchi, Ph.D.

Professor of Soil and Environmental Chemistry

Department of Agronomy

2107 Throckmorton Plant Sciences Center

1712 Claflin Road

Kansas State University

Manhattan, KS 66506 USA

785-532-7209 (office)

785-532-6094 (FAX)

http://www.agronomy.k-state.edu/research/soil-and-environment/soil-environme... http://www.agronomy.k-state.edu/people/faculty/hettiarachchi-ganga/index.htm...

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