1. By ABBAS PARVEZ KAZI
APARNA VASHIST

2. WHAT ACTUALLY BIOSORPTION IS?
 Biosorption can be defined as the ability of biological
materials to accumulate heavy metals
(bioaccumulation) from waste water through different
types of biosorbents like fungi, yeast, bacteria and
orange peel .
 It can also defined as “a non directed” physio-chemical
interaction between biosorbents and heavy metals
ion.

3. BIOSORPTION AS AN ADVANCE
SEPRATION TECHNIQUE
 In present situation, heavy metals’ pollution has
become one of the most serious environmental
problems.
 There are many process like electrochemical
treatment, oxidation/reduction, ion exchange and
membrane technology but they are ineffective and
even expensive.
 Whereas biosoption is a process which is effective and
even easy to perform.

4. SELECTION OF ORANGE PEEL AS
BIOSORBENT
 Orange is abundantly used in
soft drink industries & its peel is
usually treated as wastes.
 It is mostly composed of
cellulose, hemi-cellulose,
chlorophyll pigments and other
pigments which contain many
hydroxyl functional groups
(-OH) thus making it a potential
matrix to adsorb heavy metals.
 Conventional adsorbents like
activated carbon are
economically non-viable &
inefficient.

5. PREPRATION OF ORANGE PEEL
BIOSORBENT.
 The collected orange peels were dried in the sun for 4-
5 days crushed using a crushing mill
powdered materials were sieved using a 425 mµ sieve
twice washed with 0.01 M HCl (10 g/1 litre)
then with an extensive volume of distilled water, in
order to remove soil or debris finally with distilled
water again then oven-dried at 90 ◦C for one day.

6. OTHER SOLUTIONS USED
 Before beginning the experiment, other solutions that
are prepared include:
1. Sodium Thiosulphate (Burette solution; 0.001 M)
2. Potassium Dichromate (0.01 M)
3. Starch solution (indicator)
4. Potassium iodide (10% w/v)
5. Acetic Acid
6. Various Adsorbate solutions

7. EXPERIMENTAL PROCEDURE
I. STANDARDIZATION
II. ESTIMATION

8. I. STANDARDIZATION
 Includes standardization
of Sodium Thiosulphate.
 Conical flask 50 mL
H2O + 10 mL of 10% KI
along with 1-2 g Na2CO3 + 5
mL conc. HCl + 10 mL
K2Cr2O7.
 Flask dark at least 5
mins 150 mL H2O for
dilution + 1 mL starch
solution as indicator.
 This solution of the conical
flask is titrated against
Na2S2O3. The titration is
carried out three times.

9.  The reaction that takes place during standardization is
as follows:
2M2+ + 4KI → 2MI↓ + I2 + 4K+

10. II. ESTIMATION
 Conical flask 20 mL of M2+ solution 2-3 drops of
conc. HCl + pinch of Na2CO3 10 mL CH3COOH & 10
mL of 10% KI 5 mins in dark 150 mL H2O for
dilution & 1 mL starch solution.
 The solution of the flask titrated against Na2S2O3.
 The end point of the titration is observed to be light
green from blue (in case of Cu2+).

11.  The reaction that takes place during standardization is
as follows:
 I2 + 2Na2S2O3 → Na2S4O6 + 2NaI

12. Various parameters affecting the
biosorption
 Effect of ph
 Effect of contact time
 Effect of initial concentration
 Effect of adsorbent dosage
 Effect of ionic strength

13. •The metal ion adsorption is affected by
the pH of the solution.
•Fig shows adsorption% of M2+ as the
function of equilibrium pH.
•It can be seen that adsorption
efficiencies of M2+ ions increases with
the increase in pH.
•Almost all metal ions are absorbed to
the extent of 80-100% at weakly acidic
conditions.
•Order:
Pb2+＞Cu2+＞Cd2+＞Zn2+＞Ni2+
EFFECT OF pH

14. Effect of contact time
 Contact time is a fundamental parameter in
adsorption.
 It is important to study its effect on the capacity of
retention of copper, zinc, lead, cadmium and nickel by
orange peel.
 It can be seen that the adsorption process proceeds
rapidly and the adsorption equilibrium can be attained
within 20 minutes.

15. Effect of Initial Concentration
 The trend of removal of the heavy metals is
irrespective of the adsorbent used.
 It does not even depend upon the initial concentration
of metal ions in the solution.
 High percentage of removal was observed for lower
concentration of heavy metals for the orange peel. The
uptake of metal per unit weight of adsorbent was
same.

16. Effect of adsorbents dosage
 To study the influence of the liquid to solid ratio on the retention of the
metal ions, 3 diff values taken by varying the adsorbent amount of the
support while keeping the volume of the metal solution constant.
 Adsorption increases with the increase in the amount of the
adsorbents. This can be explained by a greater availability of the
exchangeable sites or surface area at higher amount of the adsorbent.
 The adsorption percentage increases from the doses of 0.25 g/100ml
to1 g/100ml rapidly. But no significant adsorption was found beyond
1g/100ml.

17. Adsorption Equilibrium Isotherm
 Langmuir isotherms model: in which the amount
metal uptake by biomass reaches equilibrium model.

18. Langmuir Isotherms Model
 The influence of M2+
concentrations on
adsorption was obs.
 It appears that initially
adsorption capacities
increase with increase of
ion concentration in
equilibrium metal & then
tend to approach constant
values.
 It suggests these metal
ions are absorbed onto the
orange peel according to
the Langmuir adsorption.

19. Figure shows the
rearranged experimental
data according to Langmuir
adsorption model equation.
 The values of the
adsorption capacity qm, &
Langmuir constant b were
obtained from linear
regression and the results
are presented in the table.

20. Metal qm/(mg·g−1) b/(L·mg−1) R2
Cu2+ 77.60 0.1491 0.9999
Cd2+ 76.57 0.0586 0.9642
Pb2+ 218.34 0.0564 0.9595
Zn2+ 49.85 0.1379 0.9912
Ni2+ 15.45 0.1003 0.9982
It can be seen that the R2 values of all metal
ions were close to 1, revealing the extremely
good applicability of the Langmuir model to
these adsorption processes.

21. CONCLUSION
 Thus orange peel is an excellent adsorbent for the removal
of heavy metals from their aqueous solutions.
 The small variation in the adsorption capacity of the
adsorbent is due to the variation in affinity of the
adsorbent for different metal ions.
 We also saw the effect of various experimental parameters
on adsorption capacity of the adsorbent. These
investigations are quite useful in developing a wastewater
treatment plant. The process is economically feasible and
easy to carry out.

22. THANK YOU!
Any Questions??