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Modelling batch reactor experiments with adsorption


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Hi, I am trying to model some batch reactor experiments. Set up using kinetics scripts for the reactions but also want to include adsorption. The problem is how to set up so that there is an initial adsorbed composition that is in equilibrium with the local groundwater. In the experiments we take the sediments collected from core and add some contaminated water and monitor the reaction progress to provide data for history matching using the model. This then helps get what reactions are happening and rates. There are adsorption sites present and they are occupied so have an impact on the water composition as they desorb and new adsorption composition establishes during the batch run. I am not sure how to set this up using React. I can run it in PHREEQC since you are able to assign a adsorption composition using SURFACE. Any ideas would be great!

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Hello Dirk,

You can set up sorption reactions by loading in a surface dataset. The dataset holds information needed to perform sorption reactions in your system. Depending on the sorption model you choose, your surface data will consist of slightly different parameters. Very likely, you would need to edit the surface datasets distributed with The GWB specifically to your system. I would recommend you create a duplicate of a surface dataset distributed with The GWB (e.g. IonEx.sdat or FeOH.sdat) and make changes using TEdit. For more information on sorption in the GWB, please refer to section 2.5 Sorption onto mineral surfaces in the GWB Essentials Guide. The surface data files are distributed in a subfolder named ‘Gtdata’ where you installed the software on your computer. 

It sounds like the ‘flush model’ feature might be what you need to model your experiment. When you enable a flush model, React displaces fluid from the equilibrium system with unreacted fluid. At the start of a simulation, React will equilibrate the fluid composition in your basis pane before any reactions take place. I would recommend you setup the model with the local groundwater composition in the basis pane and then enter the contaminated fluid composition in the Reactant pane. For more information on flush model, please refer to section 3.3 Flush model of the GWB Reaction Modeling User Guide. 

Hope this helps,
Jia Wang

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