DTA + IR + BET Characterisation of the ALBUM samples · DTA + IR + BET Characterisation of the...
Transcript of DTA + IR + BET Characterisation of the ALBUM samples · DTA + IR + BET Characterisation of the...
DTA + IR + BET Characterisation of theALBUM samples
Stephan Kaufhold & Reiner Dohrmann
Analyses performed
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
XRF, XRD (powder), CEC (Cu-Triene), DTA, IR, BET, LECO Missing:
XRD coarse fractionsXRD clay fraction (texture slides)XRD Rietveld calculation (AQ®)CEC (AgTu, BaCl2)LCD (alkylammonium)
XRD powder
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Some minerals questionable…What might help ?
JNB Album CAN Album ROK Album CAL Album COB Album IBE Album LOT Album ASH Album FRI Album FEB Album IKO Album´Kunigel V1´ ´Deponit Ca N´ ´Rokle´ ´Calcigel´ ´Callovo Oxf.´ ´IBECO Seal´ ´MX 80´ ´Asha 505´ ´Friedland´ ´Febex´ ´Ikosorb´
Bentonite Bentonite Bentonite Bentonite Clay Bentonite Bentonite Bentonite Clay Bentonite BentoniteJapan Milos? CzechRepl. Bavaria? Bure, F ?? Wyoming, US India Germany Almeria, Sp. Milos, Gr
XRDMontmorillonite + + + + ? + + + + +Mixed layers ? +-Musc/Illite - +- +- - - +-Quartz +- - +- + - +- + -Feldspar - - -Clinoptilolite -Calcite - - - + - - -Dolomite - - -Aragonite -Kaolinite -- - +- +-Chlorite - -Cristobalite - -Gypsum -- -Goethite -Siderite -Rutile/Anatase - --Apatite --Pyrite - - - -- --
Of course: LECO, IR, DTA
Infrared-spectroscopy
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Weigh 1 mg sample and 200 mg KBr: Mixing by mortar
Press a pellet out of the mixture
Measure background(200 mg KBr only)
Measure sample
VakuumIR
-sou
rce
dete
ctor
Infrared-spectroscopy
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Advantage 1low detection limitkaolinite, organic matter, carbonates, quartz, (sulphates)
7007508008509009501000
rela
tive
abso
rban
ce
wavenumber [cm-1]
AlA
lOH
(!k
aolin
ite!)
JNB
ROK AlF
eOH
(c
arbo
nate
)
AlM
gOH
Qua
rtz
Advantage 2octahedral layer compositionof smectites can be estimated(e.g. Fe-rich or not)
Infrared-spectroscopy
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Disadvantage 1a lot of minerals cannot bedetected being present as minor component
Disadvantage 2quantitative information canbe obscured by microstructure
IR
no quartz
Differential thermal analysis
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Weigh appr. 200 mg in Pt-cruciple
sample is heated and investigated with respect to
weight loss
energy (exo-, endo-thermal reaction)
CO2, H2O, SO2by massspectrometry
ovenoven++balancebalance
MSMS
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50 150 250 350 450 550 650 750 850 950 1050
T [K]
H2OH2O
dehydroxylationcis vacant mont
/ low Fe
dehydroxylationtrans vacant mont
/ high Fe
JNB
ROK
Differential thermal analysis
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Advantage 1low detection limitsulphides, sulphates, organicmatter, carbonates
Advantage 2information about octahedrallayer vacancy and/or Fe content can be gained
Some scientists claimthat peak positiondepends on vacancy. However, a strongcorrelation of FeVI-content withdehydroxylation at 500°C is known !!
JNB
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
XRD: montm., quartz, clinopt., calcite
Where is S ?
LECOCtotal [wt.%] 0.43Corg [wt.%] 0.07Cinorg [wt.%] 0.36
Stotal [wt.%] 0.34
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0.00
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50 150 250 350 450 550 650 750 850 950 1050
T [K]
H2OCO2SO2DSC
MS small SO2 peakDSC: exothermal=> some sulphide
dehydroxylation
CO3 decomposition
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50 150 250 350 450 550 650 750 850 950 1050
T [K]
CO2SO2
MS small SO2 peakDSC: exothermal=> some sulphide
CO3 decomposition
Decomposition of organic matter
pyrite0.5-1 wt.%(difficult tosee with XRD)
ROK
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
XRD: montm., muscov., quartz, rutile/anatase?, apatite?
LECOCtotal [wt.%] 0.27Corg [wt.%] 0.17Cinorg [wt.%] 0.1
Stotal [wt.%] 0.02
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0.00
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0.00
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50 150 250 350 450 550 650 750 850 950 1050
T [K]
H2OCO2SO2DSC
recrystallization
water (oxidation of OM) dehydroxylation
Cis + trans vacant mont
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50 150 250 350 450 550 650 750 850 950 1050
T [K]
CO2SO2
organic matter
carbonates
A closer look to IR
ROK
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
XRD: montm., muscov., quartz, rutile/anatase?, apatite?
LECOCtotal [wt.%] 0.27Corg [wt.%] 0.17Cinorg [wt.%] 0.1
Stotal [wt.%] 0.02IR: tracekaolinite
carbonate at detection limit
F-rich mont. (0.7 FeVI/EC)
muscovitequestionable
400900140019002400290034003900
wavenumber [cm-1]
rela
tive
abso
rban
ce
ROKROK 150°C
SiO
Qua
rtz/C
TO
Kaol
inie
t/Hal
loys
ite
dioc
tahe
dral
sm
ectit
e
wat
er
wat
er
carb
onat
e
Apat
ite?
Mus
covi
te?
20002200240026002800300032003400360038004000
rela
tive
abso
rban
ce
wavenumber [cm-1]
Kao
linie
t/Hal
loys
ite
dioc
tahe
dral
sm
ectit
e wat
er
C-C
org
anic
mat
ter
400600800100012001400160018002000
rela
tive
abso
rban
ce
wavenumber [cm-1]
Qua
rtz/
CTO
wat
er
carb
onat
e
Apa
tite?
Mus
covi
te?
Fe-r
ich
mon
tmor
illon
ite
750770790810830850870890910930950970
Wellenzahl [cm-1]
rela
tive
Abs
orpt
ion
AlA
lOH
- FeA
lOH
+ Fe
AlO
H
AlM
gOH
Bei
delli
t
SiO
(Qz)
/FeF
eOH
Bei
delli
t
MgVI
0,30
0,66
0,60
0,75
FeVI
0,81
0,82
0,61
0,45
887
882
877
879
K-F
sp
M
RB
UA
FE
y = -24,05x + 897,42R2 = 0,9588
876
878
880
882
884
886
888
0,4 0,5 0,6 0,7 0,8 0,9
Fe-Atome/EZ
Pos
ition
der
FeA
lOH
-Ban
de [c
m-1
]
FE
ROK
Conculsions
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
DTA and IR complement XRD results
DTA and IR are consistent with LECO analysis(no discrepancies between IR, DTA, LECO detected)
LECO provides accurate figures related to the abundance of important minerals as sulphides & sulphates, carbonates –even small changes (before and after) can be detected !
Detection limits (ca.)Cinorg Sulphides Sulphates Kaolinite
Infrared 0.2 wt.% / > 1 wt.% 0.1 wt.%DTA-MS 0.1 wt.% 0.1 wt.% 0.2 wt.% > 1 wt.%
What do we learn from BET ?
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
N2 adsorption ⇒ microporosity rather than real surface areaLeaching creates micropores ⇒ changes can be observedBET SSA depends on Ca / Na occupation… why ?
y = 1,0x + 7,2R2 = 0,3
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60 70 80
Ca2+ [meq/100g]
BE
T S
SA
[m2 /g
]
PhD Ms. Klinkenberg (microstructure and physical propertiesof clays) provides some insight !
What do we learn from BET ?
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
Bentonite moroccoCa and Na saturateddispersed & dried
CaCa NaNa
BET SSA depends on micro- and mesoporosity and henceon microstructure (arrangement of minerals to each other)
dense & lamellarmicrostructure
loose & ´card-house´ relatedmicrostructure
96 m96 m22/g/g 51 m51 m22/g/g
What do we learn from BET ?
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
In case of LOT A2 experiment BET reflects gypsumprecipitation (in pores)
0
2
4
6
8
10
12
14
16
18
0 10 20 30 40 50 60 70 80 90 100
distance from Cu tube [mm]
spec
ific
surfa
ce a
rea
[m2 /g
]
BET SSA is suitable to detect ´changes´ of the clay, however, the physical meaning might be different
DTA + IR + BET Characterisation of theALBUM samples
Stephan Kaufhold & Reiner Dohrmann
…
LECOCtotal [wt.%] 3.94Corg [wt.%] 0.65Cinorg [wt.%] 3.29Stotal [wt.%] 0.68
COB
Kaufhold & Dohrmann: DTA and IR of ALBUM samples
XRD: montm/ML, muscov., quartz, fsp., calcite/dolomite, kaolinite, chlorite, pyrite?
400600800100012001400160018002000
rela
tive
wavenumber [cm-1]
Car
bona
te