MODIFIED CLAY SORBENTS
FOR WASTEWATER TREATMENT
AND IMMOBILIZATION
OF HEAVY METALS
IN SOILS
Juris Burlakovs, Maris Klavins,
Zane Vincevica-Gaile,
and Mara Stapkevica
University of Latvia
UNIVERSITY OF LATVIA
Faculty of Geography and
Earth Sciences
Geography
Geology
Environment
Department of
Environmental
Science
2
TOPICALITY
BALTIC
SEA
GULF OF
RIGA
RUSSIA
ESTONIA
LATVIA
There are many
contaminated sites
with heavy metals,
also in Latvia!
LITHUANIA
BELARUS
Heavy metals in large doses
are toxic to environment and
human beings
3
ENVIRONMENTAL CASES
Legislation normatives in Latvia
Element
Cd
As
Ni
Cr
Cu
Zn
Pb
Hg
0,08
2
3
4
4
16
13
0,25
Precaution B, mg kg-1
3
10
50
150
30
250
75
2
Critical C*, mg kg-1
8
40
200
350
150
700
300
10
Boundary values
Target A, mg kg-1
*Regarding legislation in Latvia on soil quality
Freeport contaminated soil site, mg kg-1
Cd
As
Ni
Cr
Cu
Zn
2,3
255
10,9
9,4
1145 1455
Pb
Hg
620
10,9
4
HOW TO DO THAT???
SOIL REMEDIATION METHODS
Barriers and
Treatment
Walls
Chemical
Treatment
Soil
Amendments:
Clay?
Soil Washing
Stabilization / Solidification
(S/S technologies)
Vitrification
Separation /
Concentration
Process
Electrokinetic
Methods
Soil Vapor Extraction & Air
Sparging (for VOC’s most)
Soil Flushing
Bioremediation
Phytoremediation
5
CLAY
• Crystalline hydrated alumosilicate with cage-like
structure
• High internal and external surface area with a
negative charge neutralized by exchange
cations
• Can be suggested as an heavy metal ion
removal agent due to its cost-effectiveness and
high efficiency
6
CLAY APPLICATIONS
7
DEVONIAN CLAY IN LATVIA
8
QUATERNARY CLAY IN LATVIA
9
SCOPE OF THE STUDIES
• Optimal removal of heavy metal ions from
aqueous medium can be achieved by
adsorption process considered having best
efficiency
• The aim is to create good sorbent materials
from clay for wastewater treatment and
immobilization of heavy metals in soil
10
TASKS
• To modify illite clay by protonation, with Ca
and Na salts and hydroxyapatite
• To determine physical-chemical properties
important for sorption – HAp modification as
an example
• To perform batch kinetic experiments for lead
(II) sorption
• To analyze and compare sorption kinetics of
modified clay and raw clay
11
Field work
BALTIC
SEA
Experimental
work
Analytical
work
Sorption
kinetics
GULF OF
RIGA
LATVIA
RUSSIA
ESTONIA
LITHUANIA
BELARUS
Lielauce Quaternary clay deposit
1.1-5.3 m thick, dominantly illitic,
clayey fraction (<0.005 mm)
varies 36-43 %
12
Field work
Experimental
work
Analytical
work
Sorption
kinetics
8 g of clay
30ml DI water
10ml (1M) CaCl2
12h for swelling
KH2PO4 is added to get Ca/P calculated proportions
pH 9.0 with NH4OH (1M)
12h decanting and washing with D/I water until neutral
Ethanol for final removal of salts
Temperature 105ºC until liquid evaporated
Gallenkamp Plus II at temperature 45C for 8h
13
Field work
Experimental
work
Analytical
work
Sorption
kinetics
 Powder X-Ray Difractometry (PXRD)
 Scanning Electron Microscopy (SEM)
thin layer of gold
and palladium powder
ion coater (JB-3, Eiko, Japan)
 Brunauer–Emmett–Teller (BET) test
nitrogen multilayer adsorption
Micromeritics instrument:Gemini2360
14
Field work
Experimental
work
Analytical
work
Sorption
kinetics
Clay sorption capacity
2.5 mmol L-1 methylene blue
for
0.3 g of clay
suspensions were shaken for 24 h
centrifuged
The changes in adsorbate (methylene blue)
Yenway spectrophotometer (l=1 cm, =664 nm)
15
Field work
Experimental
work
Analytical
results
Sorption
kinetics
• BET surface for modified clay becomes
2...3 fold larger comparing to raw clay
• Methylene blue analysis show
significant increase in cation base
saturation value
• Physical chemical properties such as
specific surface and BET surface show
the immobilization potential regarding
heavy metals in aqueous medium or soil
16
Field work
Experimental
Analytical
results
Sorption
kinetics
17
Field work
Experimental
Analytical
results
Sorption
kinetics
18
Field work
Experimental
Analytical
work
Sorption
experiment
50 mL of 100 mg L-1 Pb (II) solution – 0.025g sorbent
5, 15, 30, 60, 180, 360, 480 and 1440 minutes
filtered and analyzed for residual lead content by FAAS
19
Field work
Experimental
work
Analytical
work
Sorption
kinetics
Lead sorption by Lielauce clay raw, protonated, modified with Ca
and Na salts, hydroxyapatite
20
NOVELTY
•
Innovative clay sorbents produced from
local resources can be offered for applied
remediation – hydroxyapatite modified clay
as potential sorbent has not been studied
before
•
Data on physical-chemical properties of
hydroxyapatite modified Quaternary clay
give contribution to information on potential
use of clay resources
21
SUMMARY
•
Pilot kinetic tests have shown that most effective
results for lead sorption from aqueous spiked
solution under natural conditions were achieved
by using hydroxyapatite and Ca salts modified
clay
•
Sorption reached 138 and 82 mg of lead for
gram of HAp and Ca salt modified clay sorbent
thus exceeding the result achieved by raw clay
3.5...4.5 times
•
SEM and PXRD patterns approve that
hydroxyapatite crystals were produced in clay
structure
22
From the Lab to Remedial
Decisions...???
Towards more
studies…
23
Paldies par uzmanību!
THANK YOU FOR ATTENTION!
•
•
•
02.05.2014
Juris Burlakovs©
juris@geo-it.lv