Re: [Ifeffit] Ifeffit Digest, Vol 212, Issue 7

Mike made a very good point. Both of the lower-energy features do seem unusually intense relative to the normalized background, at least in comparison to most Fe or Al bonded phosphate species that I've seen. On Fri, Oct 16, 2020 at 1:56 PM Mike Massey wrote:

Hmm fair enough. I'm not necessarily claiming it's not a "real" feature, but I would definitely be cautious of going looking for an interpretation of this one until I was absolutely sure.

To me, 5000 ppm potentially seems a bit high still, but I don't know the detector or setup you're using, or how many replicate spectra you are comfortable with taking. Maybe a 2:1 or 3:1 dilution would at least be worth trying, just from looking at the spectrum it seems like you may have room to go lower.

But I'm also curious to dig through my notes and data so I'll do that as soon as I can, too.

Cheers,

Mike

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On Oct 17, 2020, at 1:29 AM, Ganga Hettiarachchi wrote:

Hello Dean, Thanks for this interpretation; it makes sense. I was (am still) quite surprised by the intense of Al(III) pre-edge feature as we did not detect anything else in our XRD work, except some Fe oxides (the product is X-ray amorphous most likely).

Hello Mike, Thanks. We diluted this sample already to bring P concentration below 5000 mg/kg. We can potentially try further diluting, but when we go below that, sometimes we have a hard time getting a reasonable P spectrum in environmental samples.

Best regards,

Ganga

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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...

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http://www.agronomy.k-state.edu/people/faculty/hettiarachchi-ganga/index.htm...

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-----Original Message----- From: Ifeffit [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On

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Sent: Friday, October 16, 2020 4:53 AM To: ifeffit@millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 212, Issue 7

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Today's Topics:

1. Re: P K-edge XANES spectrum question (Dean Hesterberg) 2. Re: P K-edge XANES spectrum question (Mike Massey)

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Message: 1 Date: Fri, 16 Oct 2020 05:21:58 -0400 From: Dean Hesterberg To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] P K-edge XANES spectrum question Message-ID: Content-Type: text/plain; charset="utf-8"

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

Behalf Of ifeffit-request@millenia.cars.aps.anl.gov 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.

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Dean

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

wrote:

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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-env ironment-chem/

http://www.agronomy.k-state.edu/people/faculty/hettiarachchi-ganga/ind ex.html

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-- DEAN HESTERBERG William Neal Reynolds Distinguished Professor of Soil Chemistry Dept. of Crop and Soil Sciences NC State University

email: dean_hesterberg@ncsu.edu