Solubility kinetics PHREEQC

[IliasBouchkira]

Dear all

I am using phreeqc since 2017 but for equilibrium studies only. Today, I need to start some kinetic studies (kinetics of H2 solubility in a solution containing NaCl and Calcite for example).

I would like to know if there are any codes available (on this forum for example) that I can adapt for my case studies.

Many thanks in advance;

Ilias.

[dlparkhurst]

Here is a script from a recent post that considers kinetic dissolution of CO2(g). A target partial pressure of CO2 and a rate constant are defined in the KINETICS definition.

There will be other considerations for H2(g) because it will reduce carbonate to methane if equilibrium redox is established. There are recent posts about H2 storage. Many consider using Hdg(g) (phreeqc.dat and pitzer.dat) as an unreactive version H2(g), possibly using kinetics to convert Hdg to reactive H2. If you search for "Hdg" you will find several threads.

Code: [Select]

RATES
CO2_dissolution
20 k = parm(2) / 86400
30 eq_CO2 = 10^PARM(1)*10^LK_PHASE("CO2(g)")
40 act_CO2 = ACT("CO2")
50 moles = k * (eq_CO2 - act_CO2) * TIME
60 SAVE moles

END
SOLUTION
KINETICS
CO2_dissolution
-formula CO2 1
-parm 0 1 # target log PCO2(g), rate constant 1/day
-time 500000 in 10
USER_GRAPH 1
    -axis_titles            "Time, in days" "LOG P(CO2(g))" ""
    -initial_solutions      false
    -connect_simulations    true
    -plot_concentration_vs  x
  -start
10 GRAPH_X TOTAL_TIME/86400
20 GRAPH_Y SI("CO2(g)")
  -end