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PHREEQC



Hi,

I'm new to PHREEQC (usually use Geochemist's Workbench but our PC has died)
and could use some help formulating an aqueous speciation problem...

I am trying to produce pH and species concentration data (to eventually
construct a speciation diagram) for Cu++ in pure water and Cu++ in 0.1 M
NaNO3.  I require both calculations to be performed with the suppression of
CuO (s)  and Cu(OH)2 (s) and then would like to repeat the calculations with
the suppression of just CuO (s) (so letting Cu(OH)2 (s) precipitate).

I have amended the llnl database to include the following aqueous species

Cu+2 + H2O = CuOH+ + H+
    log_k    -8.2
Cu+2 + 2 H2O = Cu(OH)2 + 2 H+
    log_k     -17.5
2Cu+2 + 2 H2O = Cu2(OH)2+2 + 2 H+
    log_k    -10.59
Cu+2 + 3 H2O = Cu(OH)3- + 3 H+
    log_k    -27.8
Cu+2 + 4 H2O = Cu(OH)4-2 + 4 H+
    log_k    -39.6

and solids

Cu(OH)2(s)
        Cu(OH)2 + 2H+ = Cu+2 + 2H2O
        log_k = 9.12

and i have removed Cu+ (and all references to it).

I have successfully produced two speciation output files in pure water (see
attached) - at pH 6 and 8 - to illustrate the increasing extent of
Cu(OH)2(s) precipitation with pH (seen as a change in the SI for Cu(OH)2
(s))....do i now assume that the Cu++ deficit (ie: the difference between
the total Cu++ in the system and the total Cu++ aqueous species as listed in
the output file) is the mol/L of precipitate?

So in summary!  Could you help me produce

a) speciation of Cu++ in pure water; CuO(s) and Cu(OH)2(s) suppressed
b) speciation of Cu++ in 0.1 M NaNO3; CuO(s) and Cu(OH)2(s) suppressed
c) speciation of Cu++ in pure water; CuO(s) suppressed - so eventual
speciation diagram actually showing the fraction of Cu(OH)2(s) present with
pH
d) speciation of Cu++ in 0.1 M NaNO3; CuO(s) suppressed - so eventual
speciation diagram actually showing the fraction of Cu(OH)2(s) present with
pH

Thank you in advance for your help

Caroline Peacock

*****************************************
Caroline L. Peacock
Environmental Geochemistry
Department of Earth Sciences
University of Bristol
Wills Memorial Building, Queens Road,
Clifton, Bristol, BS8 IRJ, UK.

Tel: +44 117 9545246
Fax: +44 117 9253385

http://mineral.gly.bris.ac.uk/
*****************************************



   Input file: CuS1
  Output file: CuS1pH6s.out
Database file: cocosolid.dat

------------------
Reading data base.
------------------

	LLNL_AQUEOUS_MODEL_PARAMETERS
	SOLUTION_MASTER_SPECIES
	SOLUTION_SPECIES
	PHASES
	EXCHANGE_MASTER_SPECIES
	EXCHANGE_SPECIES
	SURFACE_MASTER_SPECIES
	SURFACE_SPECIES
	RATES
	END
------------------------------------
Reading input data for simulation 1.
------------------------------------

	TITLE Speciating Copper in water
	SOLUTION 1
	        units   ppm
	        pH      6.00
	        temp    25.0
	        Cu		25.00
	SAVE SOLUTION 1
	END
-----
TITLE
-----

 Speciating Copper in water

-------------------------------------------
Beginning of initial solution calculations.
-------------------------------------------

Initial solution 1.	

-----------------------------Solution composition------------------------------

	Elements           Molality       Moles

	Cu                3.934e-04   3.934e-04

----------------------------Description of solution----------------------------

                                       pH  =   6.000    
                                       pe  =   4.000    
                        Activity of water  =   1.000
                           Ionic strength  =   7.550e-04
                       Mass of water (kg)  =   1.000e+00
                 Total alkalinity (eq/kg)  =   2.262e-05
                    Total carbon (mol/kg)  =   0.000e+00
                       Total CO2 (mol/kg)  =   0.000e+00
                      Temperature (deg C)  =  25.000
                  Electrical balance (eq)  =   7.642e-04
 Percent error, 100*(Cat-|An|)/(Cat+|An|)  = 100.00
                               Iterations  =   4
                                  Total H  = 1.110507e+02
                                  Total O  = 5.552535e+01

----------------------------Distribution of species----------------------------

	                                           Log       Log         Log 
	Species            Molality    Activity  Molality  Activity     Gamma

	H+                1.030e-06   1.000e-06    -5.987    -6.000    -0.013
	OH-               9.941e-09   9.635e-09    -8.003    -8.016    -0.014
	H2O               5.553e+01   1.000e+00    -0.000    -0.000     0.000
Cu(2)            3.934e-04
	Cu+2              3.698e-04   3.271e-04    -3.432    -3.485    -0.053
	CuOH+             1.741e-05   1.687e-05    -4.759    -4.773    -0.014
	Cu2(OH)2+2        3.114e-06   2.750e-06    -5.507    -5.561    -0.054
	Cu(OH)2           1.034e-09   1.034e-09    -8.985    -8.985     0.000
	Cu(OH)3-          5.348e-14   5.184e-14   -13.272   -13.285    -0.014
	CuO2-2            1.316e-19   1.161e-19   -18.881   -18.935    -0.054
	Cu(OH)4-2         9.304e-20   8.216e-20   -19.031   -19.085    -0.054
H(0)             1.587e-23
	H2                7.934e-24   7.935e-24   -23.101   -23.100     0.000
O(0)             0.000e+00
	O2                0.000e+00   0.000e+00   -45.995   -45.995     0.000

------------------------------Saturation indices-------------------------------

	Phase               SI log IAP  log KT

	Cu                0.02  -11.49  -11.50  Cu
	Cu(g)           -52.14  -11.49   40.66  Cu
	Cu(OH)2(s)       -0.61    8.51    9.12  Cu(OH)2
	H2(g)           -20.00  -20.00   -0.00  H2
	H2O(g)           -1.59   -0.00    1.59  H2O
	Ice              -0.14   -0.00    0.14  H2O
	O2(g)           -43.10   40.00   83.10  O2

------------------
End of simulation.
------------------

------------------------------------
Reading input data for simulation 2.
------------------------------------

-----------
End of run.
-----------

   Input file: CuS1
  Output file: CuS1pH8s.out
Database file: cocosolid.dat

------------------
Reading data base.
------------------

	LLNL_AQUEOUS_MODEL_PARAMETERS
	SOLUTION_MASTER_SPECIES
	SOLUTION_SPECIES
	PHASES
	EXCHANGE_MASTER_SPECIES
	EXCHANGE_SPECIES
	SURFACE_MASTER_SPECIES
	SURFACE_SPECIES
	RATES
	END
------------------------------------
Reading input data for simulation 1.
------------------------------------

	TITLE Speciating Copper in water
	SOLUTION 1
		temp    25.0