Analyses planAnalyses planModule 19Module 19
ConductivityConductivity {H{H++} determined using pH electrode } determined using pH electrode Major base cations to be determined Major base cations to be determined
by ICP-AES by ICP-AES Major anions to be determined by ICMajor anions to be determined by IC Total organic carbon Total organic carbon Al fractionationAl fractionation
ConductivityConductivity Master student lab V150 Ecoscan Con5 (Eutech instruments)
conductivity meter. The instrument is calibrated using
1000 and 1433 µS calibration solutions The measurements are done for
quality control purposes in order to compare measured and calculated conductivity
{H{H++} determined using pH } determined using pH electrodeelectrode
Master student lab V160Master student lab V160 Thermo Orion model 720 pH-meter with a Thermo Orion model 720 pH-meter with a
Blueline 11-pH electrode. Blueline 11-pH electrode. The pH-meter is calibrated with The pH-meter is calibrated with
pH = 4.00 and 7.01 buffer solutionspH = 4.00 and 7.01 buffer solutions
Presented by XiePresented by Xie
Major base cations to be Major base cations to be determined by ICP-AESdetermined by ICP-AES
CaCa2+2+, Mg, Mg2+2+, Na, Na++, K, K++
• Method will be demonstrated in Method will be demonstrated in Module 24Module 24
Appropriate calibration solutions are Appropriate calibration solutions are prepared by Xieprepared by Xie
Conducted by Anne-Marie SkramstadConducted by Anne-Marie Skramstad
Major anions to be determined by Major anions to be determined by Ion Chromathograph (IC)Ion Chromathograph (IC)
Analytical Chemistry lab Analytical Chemistry lab Ø109Ø109
Tot-F, ClTot-F, Cl--, NO, NO33--, SO, SO44
2- 2-
PrinciplePrinciple• The sample is injected in a The sample is injected in a
flow of eluentflow of eluent• The analyte ions are The analyte ions are
separated by different degree separated by different degree of binding to the active sites of binding to the active sites on the ion exchange materialon the ion exchange material
• Ions with opposite charge of Ions with opposite charge of the analyte is exchanged with the analyte is exchanged with HH++ or OH or OH--
• The activity of the analyte is The activity of the analyte is and accompanied Hand accompanied H++ or OH or OH-- in in the eluent stream is measured the eluent stream is measured by means of a conductometerby means of a conductometer
Presented by Hege Lynne et alPresented by Hege Lynne et al
Total organic carbonTotal organic carbon Analytical chemistry lab Ø 104Analytical chemistry lab Ø 104 High temperature (680C) High temperature (680C)
catalytic combustion analysis catalytic combustion analysis on a on a Shimadzu TOC-5000A Shimadzu TOC-5000A instrumentinstrument
Principle:Principle: The organic carbon is combusted The organic carbon is combusted
to COto CO22 by high temperature and by high temperature and catalysis. The amount of COcatalysis. The amount of CO22 produced is measured using av IR produced is measured using av IR detectordetector
Presented by Hege Lynne et al.Presented by Hege Lynne et al. Analytes measured may include: Analytes measured may include:
TC, IC, TOC, NPOC, and POC TC, IC, TOC, NPOC, and POC
Al fractionationAl fractionation Master student lab V160Master student lab V160 Method presented as example in Method presented as example in
Lecture 1 (slide 15)Lecture 1 (slide 15) Presented by Xie)Presented by Xie)
Download manual from Download manual from http://folk.uio.no/rvogt/KJM_MEF_4010/http://folk.uio.no/rvogt/KJM_MEF_4010/
QC of dataQC of data
After the analysis the After the analysis the data must be compiled data must be compiled and quality controlled by and quality controlled by ion balance and ion balance and agreement between agreement between measured and calculated measured and calculated conductivityconductivity
For this purpose you may For this purpose you may use the Data compilation use the Data compilation and QC worksheet and QC worksheet available at available at http://folk.uio.no/rvogt/KJhttp://folk.uio.no/rvogt/KJM_MEF_4010/M_MEF_4010/
SpeciesSpeciesin natural freshwaterin natural freshwater
Central equilibriums in natural water samplesCentral equilibriums in natural water samples
KJM MEF 4010KJM MEF 4010Module 19Module 19
Inorganic complexesInorganic complexes
Major cations in natural watersMajor cations in natural waters HH++, Ca, Ca2+2+, Mg, Mg2+2+, Na, Na++, K, K++
Common ligands in natural systems:Common ligands in natural systems: OHOH--, HCO, HCO33
--, CO, CO332-2-, Cl, Cl--, SO, SO44
2-2-, F, F- - & organic anions& organic anions IIn anoxic environment: HSn anoxic environment: HS-- & S & S2-2-
Dominating species in Dominating species in aerobic freshwater at pH 8 aerobic freshwater at pH 8 are:are:
Metal ion Dominating species % Mn+aq of
total amount of M
Mg(II) Mg(H2O)62+ 94
Ca(II) Ca(H2O)62+ 94
Al(III) Al(OH)2(H2O)4+, Al(OH)3(H2O)3
0, Al(OH)4(H2O)2- 1•10-7
Mn(IV) MnO2(H2O)20 -
Fe(III) Fe(OH)2(H2O)4+, Fe(OH)3(H2O)3
0, Fe(OH)4(H2O)2- 2•10-9
Ni(II) Ni(H2O)62+, NiCO3(H2O)5
0 40 Cu(II) CuCO3(H2O)2
0, Cu(OH)2(H2O)20 1
Zn(II) Zn(H2O)42+, ZnCO3(H2O)2
0 40 Pb(II) PbCO3(H2O)4
0 5
HydrolysisHydrolysis
85.22 H4Al(OH)OH4Al
25.17 H3Al(OH)OH3Al
55.10 H2Al(OH)OH2Al
954 H Al(OH) OH Al
6.5 HAl(OH)OHAl(OH)
75.6 HAl(OH)OHAl(OH)
6.5 HAl(OH)OHAl(OH)
954 HAl(OH)OHAl
43214aq
42aq3
3213aq 0
32aq3
212aq22aq3
11aq2
2aq3
4aq42aq0
3
3aq0
32aq2
2aq22aq2
1aq2
2aq3
pKpKpKpKp
pKpKpKp
pKpKp
.pKp
pK
pK
pK
.pK
In aqueous systems, hydrolysis reactions are important In aqueous systems, hydrolysis reactions are important Hydrolysis reactions are controlled by {HHydrolysis reactions are controlled by {H++}}
• The higher the pH, The higher the pH, the stronger the hydrolysis of metal cationsthe stronger the hydrolysis of metal cations
• E.g. AluminiumE.g. Aluminium
• AlAl3+3+aqaq denotes Al(H denotes Al(H22O)O)66
3+3+
Concentrations of dissolved FeConcentrations of dissolved Fe3+3+ species speciesTwo total Fe concentrations, Two total Fe concentrations, FeFeTT = 10 = 10-4-4M and FeM and FeTT = 10 = 10-2-2MM
FeT = 10-4 M
%F
e
0
20
40
60
80
100
FeT = 10-2 M
pH
1 2 3 4
%F
e
0
20
40
60
80
100
Fe3+
FeOH2+
Fe(OH)2+
Fe2(OH)24+
Fe3+
FeOH2+
Fe(OH)2+
8
10
12
14
16
0 2 4 6 8 10 12 14
pH
pX
pFe
pFe(OH)
pFe(OH)2
pFe(OH)3
pFe(OH)4
Dissolved Organic MatterDissolved Organic Matter Low molecular weight (LMW)Low molecular weight (LMW)
< 1000Da (e.g. C< 1000Da (e.g. C3232HH8080OO3333NN55PP0.30.3)) E.g.: E.g.:
High molecular weightHigh molecular weight 1000 - > 100 000Da1000 - > 100 000Da Humic substanceHumic substance
• Very complex and coloured Very complex and coloured substancessubstances
Enhances weatheringEnhances weathering The protolyzation of weak organic The protolyzation of weak organic
acidsacids Complexation of Al and Fe Complexation of Al and Fe
• Total congruent dissolution Total congruent dissolution
Concentrations and Concentrations and activitiesactivities
ActivityActivity {X}={X}=XX · [X] · [X]
{X} is the activity to X{X} is the activity to X [X] is the concentration to X[X] is the concentration to X XX is the activity coefficient to X is the activity coefficient to X
XX are dimensionless are dimensionless
• It is determined by: It is determined by: The diameter (å) The diameter (å)
of the hydrated Xof the hydrated X Its valence (nIts valence (nXX)) The ionic strength (I)The ionic strength (I)
n=1
n=2
n=3
n=4
• when I 0 1 when I<10-5MAnions + cations
Not possible to calculate further
than I=0.1
Debye HuckelDebye Huckel (DH) equation(DH) equation
For ionic strengths (I) For ionic strengths (I) << 0.1M 0.1M the the XX can be calculated by means of can be calculated by means of e.g. the e.g. the Debye HuckelDebye Huckel equation: equation: I < 0.1I < 0.1
I < 0.005 I < 0.005
0.5 & 0.33 are temperature 0.5 & 0.33 are temperature dependent table values dependent table values
• Presented values are for 25°CPresented values are for 25°C ååXX is a table value for the specie in question is a table value for the specie in question
))33.01/((5.0log 2 IåIn xxx
Inxx25.0log
1)005.033.01( xå
