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Electrochemical Behavior Of Mncl 2 AndNaocl For Mineralization Oxalic Acid AndCitric Acid By Oxidation Process

NCKU, July29 2011

Student : Bagus Okti Ariyanto ( ) Advisor : Yao Hui Huang ( )

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Outline

BackgroundIntroductionPaper reviewFrameworkExperiment Methods

Results and discussionConclussionsFuture work

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Background

OXALIC ACID

Name : Oxalic Aciddicarboxylic acidEthanedioic Acid

Molecular Formula : C 2H2O 4Molar Mass : 90.03 g/mol -1

Uses For : construction, joinery, furniturerestoration, beekeeping, boating, etc.

http://en.wikipedia.org/wiki/Oxalic_acid

In terms of acid strength, it is about 3,000 times stronger than acetic acid.

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Background

CITRIC ACID

Name : Citric Acid2-hydroxypropane-1,2,3- tricarboxylic acid3-carboxy-3-hydroxypentanedioic acid

Molecular Formula : C 6H8O 7Molar Mass : 210.14 g/mol -1 (monohydrate )Uses For : Foods, beverages, and personal care,

Industrial and construction, Cosmetics andpharmaceuticals, etc.

http://en.wikipedia.org/wiki/Citric_acid

Citric Acid is a weak organic acid

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Acid Behavior In Aqueous Solution

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Compound Equilibrium p K a

G /kJmol 1 H /kJmol 1 T S

/kJmol 1

HA = Acetic acid HA H+ + A 4.756 22.147 0.41 22.56

H2 A+ = GlycineH + H2 A+ HA + H + 2.351 13.420 4.00 9.419

HA H+ + A 9.78 55.825 44.20 11.6

H2 A = Maleic acid H2 A HA + H + 1.92 10.76 1.10 9.85

HA H+ + A2 6.27 35.79 3.60 39.4H3 A = Citric acid H3 A H2 A + H + 3.128 17.855 4.07 13.78

H2 A HA2 + H + 4.76 27.176 2.23 24.9

HA2 A3 + H + 6.40 36.509 3.38 39.9

H3 A = Boric acid H3 A H2 A + H + 9.237 52.725 13.80 38.92

H3 A = Phosphoric acid H3 A H2 A + H + 2.148 12.261 8.00 20.26

H2 A HA2 + H + 7.20 41.087 3.60 37.5

HA2 A3 + H + 12.35 80.49 16.00 54.49

HA = Hydrogen sulfate HA A2 + H + 1.99 11.36 22.40 33.74

H2 A = Oxalic acid H2 A HA + H + 1.27 7.27 3.90 11.15

HA A2 + H + 4.266 24.351 7.00 31.35

Thermodynamic Table (Acid)

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W hy using Electrochemical OxidationProcess?????????

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economics, as well as the reliability and the treatmentefficiency.

Electrochemical oxidation processes have proven to be anefficient and versatile technology capable of handling a widevariety of wastewaters .

Increased efficiencies can be achieved through the use of compact bipolar electrochemical reactors and threedimensional electrodes providing large surface areas.

Depending on the anode material and reaction conditions,electrochemical oxidation can either promote total oxidationof the organics to CO2 (i.e. using non active typeelectrodes ) or convert them to intermediate products.

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INTRODUCTION

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oxidant reduction half reaction E o,V

1 Fluorine F2(g) 2H + 2e- 2HF (aq) 3.06

2 Hy drox yl radical HO H + e- H 2O 2.83

3 Ozone O3 2H + 2e- O 2 H2O 2.07

4 Hydrogen peroxide H2O2 2H + 2e- 2H 2O 1 .78

5 C hlorine C l2(g) 2e- 2C l- 1 .36

6 Hypochlorite ClO - H2O 2e- Cl - 2OH- 0.90

Comparison of any Oxidant

Introduction

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Introduction D efinition of AOPs

Advanced oxidation processes (AOPs) are used for thedestruction of synthetic organic chemicals (SOCs) in water,apart from disinfection and deactivation of pathogenicmicroorganisms that are difficult to degrade biologically.

These processes include the application of ozone,hydrogen peroxide, and ultraviolet light, either individuallyor in combination O3/UV; H2O2/UV; and O3/H2O2/UV.

These processes are mediated by free-radical reactions,and are becoming increasingly complex from the standpointof scientific analysis.

Oxidation processes based on generation of hydroxylradical (HO ) intermediates. Combinations based on H2O2,O3 and UV have been investigate most heavily. 11

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Chlorine

Chlorination is used for many reasons in wastewatertreatment such as in disinfection, taste and odor control,color removal, oxidation of ammonia, iron, manganese andsulfide and BO D removal.

Most common chlorine compounds used in waste watertreatments are chlorine gas ( Cl2), calcium hypochlorite[Ca(OCl)2], sodiumhypochlorite (NaOCl) and chlorine dioxide (ClO2).

The rate and efficiencies of reactions when the chlorine isadded to the wastewater depends on temperature, pH,buffering capacity and the form in which the chlorine issupplied.

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Chlorine

Chlorine in aqueous solution produces hypochlorus acid andhypochlorite ion.

Chlorine is cheap, effective, available in large quantities, non

toxic in low concentration to higher forms of life the basicdisadvantageinclude acid generation, build up of total dissolved salts andformation of potentially carcinogenic halogenated organiccompounds

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Anode:2Cl - Cl2+2e -Cl-+H 2O HOCl+H ++2e -

Overall Reaction:HOCl OCl - + H +H++OH - H2O

Cathode:2H 2O+2e - H2+2OH -

Electrolysis Reaction in the system :

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Anode:Mn2+ + 2H 2O MnO 2 + 4H + +2e

Cathode:2H + + 2e H 2

Overall Reaction:

Mn2+ + 2H 2O MnO 2 + 2H + +H2

Cl System Mn System

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PAPE R R EV IEW

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PAPER REV I EW

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EXPE RIM E NT AL P ROC E DUR E

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A. Oxi dant (S alts) B . Obje ct ive

C. P aram e t e r D . Re actor

2 . M g Cl21 . Ox al ic ac id

1 . pH

Ele ctrolys is

r e actor

F ish- b on e

2 . S alt conc e ntrat ion

4 .E le ctrod e

3. C urr e nt

1 . N a Cl

3. M n Cl2

E. A nalys is

1 . TOC

4 . N a OC l

2 . Ci tr ic ac id

2 . AA

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Eq uipments and Procedural

R eactor

C athode

Anode

Power supply

Organic Acid SolutionSalt Solution

-

-

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R ES UL T S & DI SCU SS ION

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Condition:1. Volume 3.5 liter 2. pH i +33. Oxalic Acid 2mM ( +50ppm C )4. Cl = 20mM5. Current = 1A

Comparing Of Any Salt And NaOCl

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0 50 100 150 200 250 3000.0

0.2

0.4

0.6

0.8

1.0

T O C

r

20 mM Cl -

50 mM Cl -

10 mM Cl -

T O C / T O C

O

Time (minutes

0

20

40

60

80

100

20 mM Cl -

50 mM Cl -

10 mM Cl -

Condition:1. Vo lume 3.5 liter 2. pH i +33. Citri c Ac id 0.6 94 mM ( +50 pp m C4. Current = 5 A

The presence of MnCl 2 in the electrochemical system

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0 50 100 150 200 250 300 3502.0

2.4

2.8

3.2 20mM Cl-

50mM Cl-

10mM Cl-

p H

Time (Minutes )

Condition:1. Volume 3.5 liter 2. pH i +33. Citric Acid 0.694 mM ( +50ppm C )4. Current = 5A

Effect of amount MnCl 2 in the pH of solution

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0 40 80 120 160 200 2400 .0

0 .2

0 .4

0 .6

0 .8

1 .0

,

i

,

i 2

M n r

10 M l-

20 M l-

M n

/ M n

o

Ti ( inu t s )

0

20

40

60

80

100

Con dition :1 . Vo lume .5 lite r 2 . i + f or 10mM C l- a nd i + f or 20mM C l-

. C itric Acid 0 .694 mM ( +5 0ppm C )4 . Cu rr en t 5A

Manganese Analysis in the system

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0 20 40 60 80 100 1200.0

0.2

0.4

0.6

0.8

1.0

NaOCl = 0.5%NaOCl = 1%NaOCl = 0.1%

T O C

r

T O C / T O C

o

Time (Minutes )

0

10

20

30

40

50

0 50 100 150 2000.0

0.2

0.4

0.6

0.8

1.0

T O C

r

NaOCl = 0.1%NaOCl = 0.5%NaOCl = 1%

T O C / T O C

o

Time (Minutes )

0

20

40

60

80

100

The presence of NaOCl in the system

Condition: ( With electrochemical )1. Volume 2 liter 2. pH i +2.73. Citric Acid 0.694 mM ( +50ppm C )4. Current = 1A

Condition: ( Without electrochemical )1. Volume 2 liter 2. pH i +2.73. Citric Acid 0.694 mM ( +50ppm C )

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Effect of ClO 4-

Anion of ClO 4 - can make acid condition

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0 min

180 min120 min

60 min1 min

The Colour Of Solution In The System

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Conclussions

E lectrochemical oxidation process can degrades oxalicacid and Citric Acid successfully in the presence of C hloride ions .

M nCl 2 is the best source of chlorine to degrades Oxalicacid and Citric Acid.

TOCr can achieve 98% for oxalic acid degradation atcurrent 1A, p H 3 and 20mM Cl - of M nCl 2 for 2 hours.

TOCr can achieve 9 4 % for Citric Acid degradation atcurrent 5A, p H 3 and 20mM Cl - of M nCl 2 for 2 hours.

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F UTUR E W ORK S

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Increases Conductivity.

Use temperature variable at: 30 O, 40 O, 50 O C.

Using Low current for Citric Acid OxidationProcess.

Future W orks

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