Hello I am looking for suggestions as to why I am seeing the following. Any advice is welcome.
Adding 0.25g dose of biochar to 10mM and 20mM concentrations of Ca(NO3)2, then agitating for 24 hours to study NO3- removal by biochar
Controls are biochar + water, no nitrate solution.
Run on IC
Results show increasing nitrates over 24hr but NOT in controls? i.e no NO3- present
Is showing same even in repeat experiments and replicate error very small.
Could anyone please enlighten me as to why NO3- concentration could be increasing in treatments but not controls?
Hi Natalie, what is your biochar made of? What technology was used to produce your biochar? Do you assume that your biochar is free of NO3 - maybe it is not? Just check and use control as blank value to adjust your treatment results. Good luck Nils
I agree with Nils. From your description it is not clear if your biochar is free of nitrates. so try to prove, that biochar is not a source of nitrates.
Best regards Vit
It's weird that the control doesn't show an increase as well, so I'd guess that the char isn't a NO3 source. However, maybe the combination biochar-NO3 or the biochar and the respective cation in your experiment interact or disturb your measurement method. Maybe you could measure it in another way...
Good luck!
This results may found from feedstocks, pyrolysis temperature and duration of time that you used for the production of biochar as biochar properties depending on the above properties. So, The process involves a combination of time, heat and pressure exposure factors that can vary between processors, equipment, and feedstocks. Cheers!!
Thank you all for the replies.
The biochars are made of differing feedstocks:Miscanthus straw pellet, softwood pellet and rice husk
All were made in rotary kiln via slow pyrolysis with peak temp of 700oC. Results show increase for each biochar (regardless of feedstock). Unfortunately, I am limited as to which methods to analyse NO3- with the facilities I have available.
Could anyone suggest another method other than IC at the concentration levels mentioned? Thanks
I hope this method may help you again. Extracting Nitrate by using 1:10 (w/v) with 2 M KCl in 50 mL Falcon tubes in the dark on an end to end shaker at 150 rpm at room temperature. After each step of extraction, Falcon tubes will be centrifuged (4000 g, 10 min) and the supernatant will be decanted into clean measuring cylinders to determine the volume of the decanted extractant. Aliquots will be taken from the measuring cylinders for the quantification of nitrate. Then Nitrite can be quantified by UV-Vis absorption at 550 nm after reaction with N-1-naphtyl-ethylendiamin.
Cheers!!
I am thinking in different angles, It may happen that your biochar may be promoting Ammonifiers microbial population in the sample, resulted more conversion of NO3-N in the treated sample than control. This may be the other possibility to get higher NO3-N value in the treated sample.
Dear Natalie, I think that the procedure for studying the biochar sorption capacity should be as follows:
1. adding 0.25g of biochar to 10mM concentrations of Ca(NO3)2 (a)
2. adding 0.25g of biochar to 20mM concentrations of Ca(NO3)2 (b)
3. control - should be a solution of Ca(NO3)2
a (10mM) to 1.
b (20mM) to 2.
4. agitating for 24 hours to study NO3- removal by biochar (all solutions 1, 2, 3)
Run on IC
Sorption capacity:
1.control a (10mM Ca(NO3)2– (0.25g of biochar +10mM Ca(NO3)2 );
2. control b (20mM Ca(NO3)2 – (0.25g of biochar +20mM Ca(NO3)2;
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