I am currently working on phosphorus adsorption in biochar amended soils. The biochar amendments were rate from 0 - 20% and P-solution added at 0 - 150 mg P per sample. After fitting the data obtained into Langmuir and Freundlich Isotherms, I got some negative values. I have rerun the experiment and I am still getting very similar results. What could be the source of negative values? Could this meant that desorption took place rather than adsorption? Thank you.
I suggest you will use modern adsorption isotherm, in science there are many isotherms
Dear Augustus Ilori ,
can you share at least some of your experimental results to enable us with their interpretation, please? We also need you to state the biomass used to produce biochar and process conditions (temperature, holding time).
Kind regards, Rob.
Dear Elyor Berdimurodov,
Thank you Sir. Please which modern Isotherms would you suggest?
@ Dr. Robert Thomas Bachmann,
Thank you Sir.
The biochars were made from maize stover and sawdust, pyrolysed at average temperature of 450C for 1hr using TLUD carbonizer. File attached contains the derived Isotherms parameters.
Dear Augustus Ilori
can we see the Langmuir plots for negative control (no biochar) and in sample? Please include R2. I presume you carried out batch sorption experiments? Can you give more details about the experimental settings, please?
Maize stover biochar does contain P (Article Influence of Pyrolysis Temperature on Physico-Chemical Prope...
) so leaching is a possibility.