Zeolites and their Applications

Zeolites and their Applications
Helen M. Lang
West Virginia University
Zeolite Mineralogy
gy
• Zeolites are framework silicates, with a completely linked
framework of tetrahedra
tetrahedra, each consisting of 4 O2surrounding a cation (usually Si4+ or Al3+)
• The framework contains open cavities in the form of
channels and cages
• Channels and cages are occupied by H2O molecules and
extra-framework
extra
framework cations (K+, Na+, Ca+ and others) that are
commonly exchangeable
• Channels are large enough to allow passage of guest
species
• In the hydrated phases, dehydration occurs at
temperatures mostly below 400oC and is largely reversible
(Gunter, 2001)
Lower hardness and density than
other
h fframeworkk silicates
ili
•
•
•
•
•
Mineral
Quartz
Feldspars
Feldspathoids
Zeolites
H
7
6
5-6
3.5-5.5
G
.
2 65
2.65
2.54-2.75
2.15-2.5
2.0-2.4
“Boiling
Boiling stone”
stone
• Many zeolites fuse readily with marked
intumescence (a swelling up which results
when water is expelled during heating)
• Zeolite comes from two Greek words
meaning to boil and stone
Zeolites’ common properties
Zeolites
• High degree of hydration
• Low density and large void volume when
hydrated
y
• Stability of the crystal structure when dehydrated
• Cation exchange properties
• Uniform molecular-sized channels in dehydrated
c ysta s
crystals
• Ability to absorb gasses and vapors
• Catalytic properties
Klein, 2002
Sample Zeolite Formulas
Mineral Name
General Formula
Analcime
Na16[Al16Si32O96]·16H2O
Chabazite
(Ca0.5,Na,K)4[Al4Si8O24]·12H2O
Clinoptilolite
p
((Na,K)
, )6[[Al6Si30O72]]·20H2O
Erionite
K2(Na,Ca0.5)8[Al10Si26O72]·28H2O
Heulandite
(Na K)Ca4[Al9Si27O72]]·24H
(Na,K)Ca
24H2O
Laumontite
Ca4[Al8Si16O48]·18H2O
M li
Mesolite
N 16Ca
Na
C 16[Al48Si72O240]·64H
] 64H2O
Scolecite
Ca8[Al16Si24O80]·24H2O
Stilbite
NaCa4[Al9Si27O72]·30H2O
Some characteristic Cages of Zeolites
From Armbruster & Gunter, 2001, Crystal Structures of Natural Zeolites, RIMG, v. 45
Schematic Representation of Chabazite
Chabazite Movie – Jillian Banfield
Molecular Sieve Properties
Schematic illustration of how a zeolite sieve separates
p
a straight-chain
g
hydrocarbon (octane) from a branching-chain hydrocarbon (isooctane).
Structure of Heulandite-Clinoptilolite
Ten-membered and 8membered tetrahedral
rings form channels
parallel to the c-axis
c-axis.
Small green spheres
represent Na, larger light
blue spheres represent
K, small yellow spheres
represent Ca, large blue
spheres represent H2O
molecules.
From Armbruster & Gunter,
2001 C
2001,
Crystal
t l St
Structures
t
off
Natural Zeolites, RIMG, v. 45
(Na,K,Ca0.5)7[Al7Si29O72].22H2O
Two major occurrences of Zeolites
• As well-crystallized
well crystallized minerals found in
cavities and veins in basic igneous rocks,
coarse large variety of crystal forms and
coarse,
habits, beautiful crystals
• As large deposits of fine
fine-grained
grained zeolites
that are the diagenetic alteration products
of volcanic tuffs and volcanic glass
glass,
recently discovered in western U.S., Cuba,
Turkey Tanzania and elsewhere
Turkey,
Zeolite Crystals
Heulandite - (Ca,Na)2-3Al3(Al,Si)2Si13O36·12H2O
from Idaho
Zeolite Crystals
Scolecite –
CaAl2Si3O10·3H
3H2O
Scolecite on Stilbite
CaAl2Si3O10·3H2O – NaCa4[Al9Si27O72]·30H2O
Mesolite – Na2Ca2Al6Si9O30·8H2O
Zeolite Crystals
Analcime - Na16[Al16Si32O96]·16H2O
Isometric, trapezohedron form common
Zeolite Crystals
Stilbite (Isle of Skye)
Laumontite (India)
Pretty minerals associated with zeolites
Apophyllite – KCa4(Si4O10)2F-8H2O is a
sheet silicate commonly assoc. with zeolites
Cavansite – Ca(VO)(Si4O10)-4H2O is a
sheet silicate commonly assoc. with zeolites
Properties of Zeolites
Table from Mumpton, 1999, La roca magica
CEC smectite clays
0.8 to 1.5 meq/g
Uses of Zeolites
• Ammonium ion removal in waste stream
treatment, sewage treatment, pet litter and
aquaculture
• Odor control
• Heavy
H
metal
t l iion removall ffrom nuclear,
l
mine, and industrial wastes
• Agricultural use, such as soil conditioner
and animal feed supplement
Klein, 2002
Uses of Zeolites
• See La roca magica: Uses of natural
zeolites in agriculture and industry
• FREDERICK A
A. MUMPTON
• Proc. Natl. Acad. Sci. USA
Vol. 96, pp. 3463–3470, March 1999
Colloquium Paper
Construction Applications
• Dimension stone – altered tuff has for
millennia been cut into blocks and used as
g stone ((low density,
y high
g p
porosity,
y
a building
homogeneity, low cost)
• “Pozzolanic” cement ((pozzolan, pozzolanic =
a siliceous-aluminous material that will, in finely
divided form and in the presence of moisture,
react with CaOH to form a cement (Webster))
• Popped into low density pellets for use in
light-weight aggregates
Mumpton 1999
Dimension Stone
Castel Nuovo (Naples, Italy) constructed of tuffo giallo napolitano (Mumpton 1999)
[the Neapolitan Yellow Tuff (12ka): eruption of Vesuvius and caldera collapse]
Waste and Wastewater Treatment
• Municipal Wastewater
• Drinking water
Zeolite –filled, water-purification tanks - Denver, CO
Mumpton 1999
Agricultural Applications
•
•
•
•
Animal nutrition and food additive
Agronomy and Horticulture
A
Aquaculture
lt
Animal-waste Treatment
Mumpton 1999
“Zeoponics”
Zeoponics
• It’s
It s a new kind of growth medium
developed by NASA for space travel
• Its name is from zeolite and hydroponic
• It’s a growth medium with nutrients
• It’s a nutrient delivery system
• It’s an additive that makes other growth
g
media more effective in growing plants
“Zeoponics”
• See http://www.zeoponix.com/
• As a result of a Small Business
Innovative Research contract with
NASA, ZeoponiX, a small company in
Louisville CO
Louisville,
CO, manufactures ZeoProTM,
a combination of a nutrient-charged
zeolite and slowly dissolving substances
that contain phosphorous and other
nutrients
• Zeoponics
p
is expected
p
to be applied
pp
on
the International Space Station and in
future missions to extra-terrestrial
bodies, such as Mars and the Moon
ZeoPro is manufactured from a
naturall source off clinoptilolite
li
il li
Ca10(PO4)6(OH)2
Apatite Structure and Formula
OH-, F-, Cl-
Ca+2
Ca+2
Ca+2
PO43-
Ca5(PO4)3(OH,F,Cl)
Clinoptilolite Structure
Adsorption and Catalysis
Mumpton 1999
Nuclear Waste and Fallout
Mumpton 1999
Other Applications
• Consumer Products
• Medical Applications
Mumpton 1999
Structure of Heulandite-Clinoptilolite
Ten-membered and 8membered tetrahedral
rings form channels
parallel to the c-axis
c-axis.
Small green spheres
represent Na, larger light
blue spheres represent
K, small yellow spheres
represent Ca, large blue
spheres represent H2O
molecules.
(Na,K,Ca0.5)7[Al7Si29O72].22H2O
Sample Zeolite Formulas
Mineral Name
General Formula
Analcime
Na16[Al16Si32O96]·16H2O
Chabazite
(Ca0.5,Na,K)4[Al4Si8O24]·12H2O
Clinoptilolite
(Na,K)6[Al6Si30O72]·20H2O
Erionite
K2(Na,Ca0.5)8[Al10Si26O72]·28H2O
Heulandite
(Na K)Ca4[Al9Si27O72]·24H2O
(Na,K)Ca
Laumontite
Ca4[Al8Si16O48]·18H2O
Mesolite
Na16Ca16[Al48Si72O240]·64H2O
Scolecite
Ca8[[Al16Si24O80]]·24H2O
Stilbite
NaCa4[Al9Si27O72]·30H2O