Transcript Biosorptive Removal of Copper and Cobalt from Aqueous

BIOSORPTION OF COBALT AND COPPER
FROM HYDROMETALLURGICAL SOLUTIONS
MEDIATED BY Pseudomonas spp
PRESENTATION BY:
NONJABULO PRUDENCE DLAMINI
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PRESENTATION LAYOUT
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Introduction
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Scope of the work
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Experimental design
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Results & discussions
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Conclusions
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INTRODUCTION
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The use of micro-organisms in the dissolution of metals
bearing minerals and the removal of some anions e.g.
phosphates and ammonia is well known e.g. sulphur
oxidisers Acidithiobacillus spp, Leptospirillum spp and
Sulpholobus spp. (Acharya,1990) (Momba, 2005).
However, not much has been done on the use of
microorganisms in the removal of leached metals from their
aqueous solutions. E.g. Fixation of Ni and Fe by
Pseudonomonas species through biosorption (Danalkova et
al,2005).
In this study copper and cobalt are being removed from
hydrometallurgical solutions using microorganisms
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The use of biological methods for
heavy metal recovery have gained
considerable momentum due to their
high efficiency, low operating costs
and simplicity.
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SCOPE OF THE WORK
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This project was aimed at testing
the viability of using bacteria as;
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Alternatives to costly metal removal
techniques (water purification).
Biosorbents to recover precious metals
from
hydrometallurgical
process
solutions.
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EXPERIMENTAL DESIGN
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Sampling
•Soil & water samples were collected from water bodies around
the small scale mines.
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Sampled sites
•Acidic
•Turbidity high
•Conductivity high
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CULTURING AND IDENTIFICATION
Soil samples were suspended in distilled water,
vortexed (thoroughly mixed).
oBoth the water and soil samples supernatant
were diluted in a sterile phosphate buffer and
there after inoculated in Pseudomonas agar
base.
oThe isolation of bacteria using Pseudomonas
agar base yielded positive results meaning that
there blue-green colonies of Pseudomonas spp
were observed.
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Synthetic solutions
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Solutions of different concentrations
(0.07M, 0.33M and 0.66M) were
prepared using copper and cobalt
sulphate.
Batch scale experiments to test the
effects of
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Contact
time,
concentration,
pH,
temperature,
co-ions,
biomass
concentration were conducted.
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Metal recovery
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Bacteria : water (3:1) ratio
Bacteria were inoculated into synthetic
solutions water samples and recovery was
allowed to take place over a period of 24 h
in a shaking incubator (150 rpm) at
36.5°C.
Metal concentrations were analysed using
AAS and ICP.
Control experiments were conducted to
monitor parameters like precipitation.
The same procedure was repeated for
hydrometallurgical solutions which had
lower metal concentrations.
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Results & discussions
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Contact time and
temperature
had
an almost similar
effect on the rate
of
biosorption.
Increased up to a
certain level then
decreased.
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pH
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Maximum uptake of Cu and Co by
Pseudomonas spp was attained at pH 6.5.
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Biomass (bacterial concentration)
3:1
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Co-ions
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Mixing copper & cobalt enhanced
removal of copper.
Ionic radii
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Kinetic models
Langmuir equation model
2.55
2.35
2.15
1.95
y = -1219.9x + 9.1768
R2 = 0.8615
R2= 0.8615
1/(x/m)
1.75
1.55
1.35
1.15
0.95
0.75
0.55
0.0057 0.0059 0.0061 0.0063 0.0065 0.0067 0.0069 0.0071
1/C
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Freundlich equation model
Log C
2.14
2.16
2.18
2.2
0.2
0.1
Log x/m
0
-0.1
-0.2
y = -6.3649x + 13.903
R2 = 0.9622
-0.3
-0.4
2.22
2.24
2.26
The Freundlich equation
gave a plot with higher
correlation as compared
to the Langmuir equation.
The Freundlich gave an
R2
value
of
0.9622
whereas the Langmuir
had an R2 value of
0.8615. Therefore the
Fruendlich
plot
is
favoured
over
the
Langmuir.
R2=0.9622
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Recovery from hydrometallurgical
solutions
Sampled
site
Nigel river
Big dam
HVH mine site A
HVH mine site B
HVH mine site C
Shaft No 2 A
Shaft No 2 B
Shaft No 2 C
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Copper
% recovery
50
42
37
73
61
29
24
36
Cobalt
% recovery
45
35
65
46
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40
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INTERACTION OF MICROBES WITH
METALS (SEM)
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SEM micrograph of
the
dried
metal
solution
before
interaction
with
Pseudomonas
spp
rods.
SEM
micrograph
showing
the
dried
mixture of
metal
solution
with
Pseudomonas spp
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TEM
metal bioaccumulation on
the periplasmic wall of the
Pseudomonas spp rods.
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Conclusions
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Pseudomonas spp reclaim both copper and cobalt
from their sulphate synthetic solutions .
It tends to remove or extract more metal ions at low
concentrations and the ratio of bacteria population
to solution volume being 3:1 works best.
The maximum uptake of both copper and cobalt
occurred at a pH of 6.5 beyond which the adsorption
rates decreased.
The bacteria have successfully removed up to 45 %
of copper from 0.07M and up 40 % from 0.07M
cobalt from cobalt sulphate solutions and 73 % and
65 % of copper and cobalt respectively from mine
water samples.
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ACKNOWLEDGEMENTS
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Nigel town municipality and small
scale miners.
National research foundation and
the University of Johannesburg for
financial assistance.
Mr E. Fosso-Kankeu
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….THANK YOU…
…….THANK YOU……
?????
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