environmental biotechnology laboratory biosorption of lead,cadmium,and mercury ions on loofa sponge...

Environmental Biotechnology Laboratory

Biosorption of lead ,cadmium,and mercury ions on loofa sponge immobilized bio

mass of Aspergillus terreus

指導老師 : 孫逸民教授學生 : 田汶玄


Introduction(1)

Heavy metals are discharged from various industries such as electroplating, metal finishing, textile, storage batteries, mining, ceramic and glass.


The commonly used procedures for removing metal ions from wastewater include chemical precipitation, ion exchange, membrane separation, reverse osmosis, and electrolysis.

Introduction(2)


However, these techniques have certain disadvantages such as incomplete removal, high reagent and energy requirements, generation of toxic sludge.

Introduction(3)


The search for alternative treatment techniques has focused attention on the use of biological materials such as algae, fungi, yeast and bacteria for the removal and recovery technologies and because of the better performance and low cost of these biological materials .

Introduction(4)


The purpose of the present study is to provide an immobilized biosorption system using a low cost, physically strong, and highly porous immobilization matrix; loofa sponge.

Introduction(5)


The study investigated the use of loofa sponge immobilized fungal biomass as a biosorbent for the removal of lead, cadmium ,and mercury from aqueous solution.

Introduction(6)

Materials and Methods


Microorganism

The Aspergillus terreus was maintained by pure culturing on potato dextrose agar slants at 28 for 7 days.℃

Mycelium suspensions from 7-day old cultures, preculture on glucose at 28 for 24 hours. ℃

Then, above Mycelium suspensions was main culture for 15 days.


culture mediummedium concentration (g/l)

KH2PO45

K2HPO45

FeSO4 ． 7H2O 0.2

MnSO4 ． 4H2O 0.1

ZnSO4 ． 7H2O 0.2

CuCl2 ． 2H2O 5

H3BO311

(NH4)6Mo7O24 ． 4H2O 5

Mono-hydrate sodium glutamate

12.5

Glucose 45

MgSO4 7H‧ 2O 0.1

CaCl2 ． 2H2O 20


Pretreatment of loofa sponge

The fibrous sponge was cut into discs of approximately 0.2g , soaked in boiling water for 30 min, thoroughly washed under tap water, and left for 24 h in distilled water, changed 3-4 times.

The sponge piece were oven dried at 70 .℃


Immobilization of A.terrues within loofa sponge

The mycelium suspension (2.5 ml) was inoculated into 250 ml flasks containing 50 ml of the growth medium and pre-weighed loofa sponge discs.

The inoculated flasks were incubated at 28 and shaken at 200 rpm.℃

After 15 days of incubation, loofa sponge immobilized A.terrues were harvested from the medium, washed twice with distilled water and stored at 70 ℃ until use.


Biomass of fungal growth

The dry weight of the fungal biomass entrapped within sponge pieces was determined by weighing sponge pieces before and after fungal growth after 48 h drying at 70 .℃


Metal solutions

HgCl2 (Riedel-de Haën)

CdCl2 2.5H2O (Panreac )‧PbCl2 (J. T. Baker)


Biosorption studies The biosorption capacity of FBILS (fungal biomass immobi

lized in loofa sponge) was determined by contacting 100 ml metal solution of known concentration in 250 ml flasks.

The metal solution was shaken on an orbital shaker at 200 rpm and 30 .℃

FBILS were separated from the solution by decantation.

Residual metal concentration in the metal solutions by centrifugation at 3000 rpm for 5 min

Supernatant was analysed for residual metal ions concentration was determined using flame atomic absorption spectrophotometer.


Effect of contact time and pH on metal ion biosorption

For the determination of rate of metal biosorption by FBILS, the supernatant was analysed for residual metal ions after the contact period of 10, 20, 30, 60, 120, 240 and 360 min.

The effect of pH on metal ions sorption by FBILS was determined by equilibrating the sorption at different pH values of 2, 3. 4, and 5.


Chemical and physical stability of FBILS

For the purpose, FIBILS was shaken on an orbital shaker at different rotation speed for 2 days.

Similarly, soaking of FBILS in buffer of various pH (2.0–12.0 for 20 days) was shaken on an orbital shaker at 200 rpm for 20 days had weight loss 20% of the FBILS were observed during this period.


data analysis

q = V(Ci - Ceq)/M

q is the metal uptake (mg metal ions /g dry weight of fungal biomass entrapped within sponge)

V is the volume of metal solution (ml)

Ci is the initial concentration of metal ions in the solution (mg/l)

Ceq is the final concentration of metal ions in the solution

M is the dry weight of fungal biomass

Results and discussion


Fungal biomass immobilized within loofa sponge

(a) (b)

(a) natural loofa sponge covered with A. terrues biomass(b) artificial loofa sponge covered with A. terrues biomass


Growth curve — Aspergillus terreus immobilized loofa sponge

0

0.2

0.4

0.6

0.8

1

0 1 3 5 7 9 11 13 15 18 23 30

growth phase (day)

biom

ass

of im

mob

ilize

loof

asp

onge

(g)

natural

artificial


Effect of different phase on metal uptake by FBILS

100 ml single metal solution (6000mg/l) was contacted with different days of FBILS on orbital shaker at 200 rpm at 30 ℃ at pH3 for 30 min

0

100

200

300

400

0 3 7 15 30

diferent phase(days)

Pb a

dsor

bed(

mg/

g)

Time-course profiles for metal ion biosorption by FBILS


0

50100

150

200

250300

350

0 10 20 30 60 120 240 360 480 960

time(min)

Pb a

dsorbed(m

g/l)

0

10

20

30

40

0 10 20 30 60 120

time(min)

Cd a

dsorbed(m

g/g

) 0

10

20

30

40

50

0 10 20 30 60 120 180 240 300

time(min)

Hg a

dsorb

ed (m

g/g

)


effect of pH on metal uptake by FBILS

050

100150200250300350

1 2 3 4 5 6 7

pH

met

al ion

ads

orbe

d(m

g/g)

Pb

Cd

Hg

Metal solution was contacted with 15 days of FBILS at optimal condition


Effect of temperature on metal biosorption by FBILS

050

100150200250300350

0 10 20 30 40 50 60

temperature( )

met

al io

n ad

sorb

ed(m

g/g)

Pb

Cd

Hg

℃



Effect of rotation rate on metal biosorption by FBILS

0

50

100

150

200

250

300

350

0 50 100 150 200 250

rotation(rpm)

met

al ion a

dso

rbed

(mg/g

)

Pb

Cd

Hg


Effect of initial metal ion concentration


0

100

200

300

400

0 1000 2000 3000 4000 5000 6000 7000 8000

initial concentration (mg/l)

Pb adso

rbed

(mg/g

)

05

101520253035

0 100 200 300 400 500 600

initial concentratiom (mg/l)

Cd a

dsorb

ed (m

g/g

)

0

10

20

30

40

50

0 200 400 600 800 1000 1200

initial concentration (mg/l)

Hg adsorb

ed(m

g/g

)


Chemical stability of LIBCS

soaking of FBILS in buffer of various pH (2.0–12.0 for 20 days)

0

20

40

60

80

100

2 4 6 8 10 12

pH

wei

ght l

oss

(%)

before weight

after weight


physical stability of FBILS

0

20

40

60

80

100

50 100 150 200 250

rotation speed(rpm)

wei

ght l

oss

(%)

before weight

after weight

soaking of FBILS in pH7 buffer for 2 days

Conclusions


Loofa sponge is an effective immobilization carrier for the entrapment of A.terreus to produce FBILS.

The biosorption capacity of FBILS for single metal decreased in the order Pb > Hg > Cd

FBILS showed an excellent potential for the removal lead(II) from aqueous solution.

FBILS showed an good physical and chemical stability.

Thanks for your attention

environmental biotechnology laboratory biosorption of lead,cadmium,and mercury ions on loofa sponge...

Documents