HP1 pH differences from PHREEQC run

[ahmet19]

Hi,

I am trying to simulate uranium transport with surface complexation however HP1 results always end up with very different results from the PHREEQC GUI. I am able to get good results from PHREEQC GUI but I don't know why HP1 results are not the same with PHREEQC GUI results, particularly for pH. Even though I use pH to charge balance the solution, pH and other results deviate from the actual PHREEQC calculation. I think the deviation comes from the abrupt pH change, very low or high, and it changes the aqueous complexes. Can you clarify to me what can be wrong here and how can I modify the HP1 to get decent results?

Thanks,

Ahmet

[diederik]

Hi,

I guess you use surface complexation with -no_edl option. In that case, the solution is not neutral, but has a charge that has to be transported. You need to add an additional 'solute' to be transported, namely Charge,

Diederik