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Jeonghwan Hwang

How can i make the sorption isotherm?

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Hi, My name is Jeonghwan Hwang.

I am studying about sorption isotherm, and i want to make a sorption isotherm using GWB.

However, i cannot find how to make isotherm in any tutorial or workshop material.

Can i make the sorption isotherm?

I attached a sample which was resulted by PHREEQC.

I wonder if I can make a figure like this.

Thank you for kind reading.

 

Sincerely,

 

Jeonghwan Hwang

Sorption isotherm of PHREEQC.JPG

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Hello Jeonghwan,

To simulate sorption in GWB, prepare a surface dataset for the ion of interest. You can refer to section 2.5 for more information on the various sorption models in GWB Essentials Users Guide and section 9.2 for more information on how to edit or create new surface datasets. Using React, you can set up a simulation to titrated the ion of interest into a system and observe the mass of ion sorbed based on the sorption model (Kd, Freundlich, Langmuir) of your choice. Note that for the Kd and Freundlich approach, you would need to completely specify mineral mass, including both equilibrium and kinetic minerals as well as any inert volume. You can do so by setting a low concentration of the ion in interest in the basis pane and then in the Reactants pane, select ‘add’ --> ‘Simple’  --> ‘Aqueous’--> name of species. Enter the total quantity you want to titrate in through the simulation and run the simulation. Plot the amount of ions in solution vs. the total concentration of ions sorbed from your simulation. Note that mass of ions sorbed per unit of solid mass is not a unit you can select in Gtplot. To convert to mass of ions sorbed per mass of soil, I would recommend copying the total sorbed mass from each simulation and divide by the total mass of soil in excel or a similar program. You can then replot your results in the desired units

Hope this helps.

Best Regards,

Jia

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