[Ifeffit] P K-edge XANES spectrum question

[Mike Massey]

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 <dean_hesterberg at ncsu.edu> 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 <ganga at ksu.edu> 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-environment-chem/
>> http://www.agronomy.k-state.edu/people/faculty/hettiarachchi-ganga/index.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 at ncsu.edu
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