To determine the water quality parameters of the Buriganga river

To predict the Humic Acid structure of the Buriganga River bottom sediment

To study the complexation behavior between HA- Metals (Iron, Cadmium, Chromium, Manganese, Lead, Nickel and Calcium)

SAMPLE COLLECTION SAMPLE ANALYSIS Nine sediment samples were collected from the Buriganga river.

Eighteen water samples were collected from the Buriganga river.

The water samples were analyzed by AAS and UV-Visible for metal ions and anions

Humic acid was extracted from the sediments according to IHSS

Characterization and study of complexation with metals of extracted HA was carried out with IR, FTIR, SEM, EDX and CHNS analyzer.

Sampling stations:a) First Buriganga Bridgeb) Arsene gate, Gudara Ghat c) Sadar Ghat First Jettyd) Shaym Bazar Ghate) Sadar Ghat Main Terminalf) Sadar Ghat Fruit Bazarg) Ahsan Manzil Ghath) Second Buriganga Bridgei) Imamganj Paan Ghat j) Dhaka Dockyard k) Toil Ghatl) Keraniganj Police Ghatm) Kamrangir Chor Ghatn) Shoari Ghato) Solimullah MedicalCollege Ghatp) Jora bridge, Kamrangir Chorq) Forashganj Ghatr) Faridabad Launch Terminal

River bottom sediments

Dried under sun for 5 hours + Broken piece of shell & small dust removed

Dried sample (100g)

+ 1 M HCl (up to pH 1~2) + 0.1 M HCl (10mL Liquid/ 1g dried sample)

Solution (pH=1 to 2)

Centrifugation(700 rpm 5min)

Shaking for 1 hour

+1.0M NaOH (up to pH =7.0)

ResidueSupernatant+ 0.1 M NaOH (at N2)

Solution (pH ~ 11)

Shaking for 4 hour + Settle overnight

Centrifugation (1500 rpm 15 min)

Supernatant Residue

+ 6 M HCl (up to pH = 1.0) + Stand for 12~16 hour

Centrifugation (1000 rpm 10 min)

Supernatant- Fulvic acid

Precipitate

+ 0.1 M KOH + solid KCl (0.3M [K+])

Centrifugation (2000 rpm 10 min)

Liquid HA Precipitate

Dried in oven (50oC)

Solid HA

Figure 2: Flow Chart of extraction procedure of Humic Acid

Samples Fe2+/3+

mg/L

Pb2+

mg/L

Cd2+

g/L

Cr3+/6+

mg/L

Ni3+

mg/L

Ca2+

mg/L

Mn2+

mg/LWa 0.08 0.13 4.00 0.01 0.04 33.38 0.03Wb 0.06 0.12 2.00 0.06 0.07 52.56 0.01Wc 0.1 0.15 3.00 0.03 0.07 22.68 0.02Wd 0.12 0.12 0.80 0.02 0.04 24.34 0.04We 0.04 0.11 8.00 0.03 0.03 22.56 0.01Wf 0.04 0.12 2.00 0.01 0.06 22.62 0.07Wg 0.14 0.12 1.00 0.01 0.04 19.04 0.05Wh 0.22 0.20 0.75 0.02 0.01 20.58 0.04Wi 0.04 0.002 7.50 0.08 0.06 49.30 0.01Wj 0.32 0.04 2.00 0.04 0.07 31.50 0.11Wk 0.26 0.02 4.90 0.02 0.06 19.22 0.03Wl 0.1 BDL 0.40 0.01 0.05 14.70 0.01Wm 0.12 0.004 12.00 0.01 0.05 59.00 0.05Wn 0.18 0.04 8.50 0.03 0.04 14.66 0.01Wo 0.04 0.02 6.00 0.01 0.07 25.22 0.02Wp 0.22 0.03 16.70 0.09 0.06 20.76 0.03Wq 0.30 0.03 5.80 0.01 0.05 27.78 0.09Wr 0.28 0.04 2.00 0.03 0.02 21.04 0.02

WHO std (drinking) 0.30 0.01 5.00 0.05 - 200.00 0.10

Std. for Fishing water 0.30 0.01 5.00 0.10 - - 0.10

Table 1: Observed values of metal ions of Buriganga river with standard values

Figure 5: FTIR Spectrum of Extracted Humic Acid

(d)

Wave no.(cm-1) Region (cm-1)

Type of vibration

3280(a),3300(d),3280(g), 3280(i)

3400-3200, 3570-3450

H- bonded OH group

3000(i) 3050-3000 Aromatic C-H stretching

2960(a),2920(d),2920(g),2960(i)

2960-2850 Stretching of CH2, CH3 group

2960(a),2930(d),2960(g),2560(i)

3000-2500 OH stretch of H-bonded –COOH

1550(a),1560(d),1580(g) 1610-1550 Carboxylate anion

1650(a), 1650(d),1640(g),1655(i)

1650-1450 Aromatic C=C stretching

1400(a),1400(d),1400(g),1400(i)

1485-1340 CH deformation of CH3

1260(i) 1265-1200 Symmetric –COO- stretching

1120(a),1130(i) 1126-1100 C-O stretching of COOH

1070(a) ~1100,~1050

-C-O stretching in aliphatic OH

700,830,880(a),700,860,880(d) 840-690 Aromatic disubstituted

Table 2: FTIR analysis of extracted Humic Acid

Figure 8: SEM image of extracted Humic Acid (Buriganga River)

Figure 7: SEM image of Standard Humic Acid

Element CHNS Analysis (% Weight)

EDX (% Weight)

C 63.25 62.36

H 4.514 Not quantified

N 0.75 3.16

S 0.763 3.71

O 30.72 25.88

Table 3: Elemental Composition of extracted HA with CHNS and EDX analyzers

Figure 9: EDX Spectrum of Extracted HA

Figure 6: Proposed structure of Extracted Humic Acid

OH

COOH

HOOH

COOH

O

HO

O

NCHCOOH

RO

O

O

NH

OH

CHCH

RO

CHCH

N

OCH2

CH

O

O

OO

OHCOOH

COOH

OO

O

OH

H

Figure 10: SEM image of Humic Acid and Fe Complex

Figure 11: EDX Spectrum of HA-Iron (II) Complex

pH

1 2 3 4 5 6 7 8 9 10 11 12 13

Tran

smita

nce%

75

80

85

90

95

100

Rem

oval

%88

90

92

94

96

98

100

102

Tranmitance % vs pHRemoval % vs pH

pH

1 2 3 4 5 6 7 8 9 10 11 12 13Tr

ansm

itanc

e%

88

90

92

94

96

98

100

102

Rem

oval

%

88

90

92

94

96

98

100

102

Transmitance % vs pHRemoval % vs pH

Figure 12: Complexation study of HA with Iron (II) Sulphate at different pH at 254 nm

Figure 13: Complexation study of HA with Iron (II) Sulphate at different pH at 436 nm

Concentration of Iron (II) X 10-3 M

0.1 0.3 0.5 0.7 1.0 1.3 1.5 1.7

pH

5.2

5.4

5.6

5.8

6.0

6.2

6.4

6.6

6.8

Con

duct

ance

X 1

0-2

S

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

Concentration of Fe vs pH Concentration of Fe vs Conductance

OCC

RC

a b

Concentration of Iron X 10-3 M

0.1 0.3 0.5 0.7 1.0 1.3 1.5 1.7

Degr

ee o

f Com

plexa

tion

at 2

54 n

m

70

75

80

85

90

95

100

Degr

ee o

f Com

plexa

tion

at 4

36 n

m

30

40

50

60

70

80

90

100

Conc of Fe vs at 254 Conc of Fe vs at 436

Figure 15: Degree of Complexation inpercentage with the variation of

concentration of Iron (II) Sulphate

Figure 14: Jar test of Iron (II) - HA complexation

Metal - HA Complex Optimum pH

values

Optimum concentrations X 10-3 MBy Jar test By Spectrophotometric test

Iron (II) - Humic Acid 7 0.70 - 1.00 0.70Cadmium (II) - Humic Acid

9 0.45 - 0.70 0.55

Chromium (III) - Humic Acid

3 0.48 - 0.70 0.44 - 0.50

Manganese (II) - Humic Acid

9 0.70 - 1.19 1.50 - 1.51

Lead (II) - Humic Acid 6 - 10 0.45 - 0.70 0.46 - 0.50

Nickel (II) - Humic Acid

10 0.67 - 1.00 0.70 - 1.45

Calcium (II) - Humic Acid

8 1.18 - 1.50 1.24 - 1.30

Table 4: Summary of Metal - HA Complexation study

The formation of Metal - Humic acid complex is controlled by the number of coagulant (metal ion) species and two dynamics aspects:

(i) the reconformation of humic network (ii) the collision rate of destabilized particles.

An overall shrinkage of anionic humic network is indeed expected upon binding of cationic coagulant species which promotes the formation of intra- and inter-particle hydrophobic domains according to the extent of charge neutralization.

The collision rates determines the variations in precipitation volume in the range of optimal concentration of coagulants.

MECHANISM OF METAL - HUMIC ACID COMPLEXATION

The Buriganga river water is highly polluted

The Humic Acid Structure of Buriganga river sediment is slightly different than of other places. It contains aromatic hydrocarbons, large amount oxygen containing groups

The Buriganga river Humic Acid makes complexes with the metals.

This complexation or coagulation process can be used to remove the high concentration of metals from the surface water of this river.

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