IRONIRON& &

MANGANESEMANGANESE

ENVE 201ENVE 201

Dr. Aslıhan KerçDr. Aslıhan Kerç

http://sites.google.com/site/marmaraengineer/my-formshttp://translate.google.com.tr/translate?hl=tr&sl=en&u=http://sites.google.com/site/marmaraengineer/

IRON & MANGANESEIRON & MANGANESE

Problems in Problems in ggroundroundwwater, surface waterater, surface water certaincertain s seasons.easons.

Some underground waterSome underground waters ares are free of Fe, Mn free of Fe, Mn, but , but ssome have ome have

Biochemical changes Biochemical changes effect Fe, Mn contenteffect Fe, Mn contentChanges in environmental condition brought by Changes in environmental condition brought by biological rbiological reactions effect Fe, Mn content.eactions effect Fe, Mn content.

IRON & MANGANESEIRON & MANGANESE

Fe,Mn Fe,Mn insoluble form in soil insoluble form in soil how converted how converted to solubleto soluble??

FeFe is found is found in soils and minerals as :in soils and minerals as : insoluble ferric oxideinsoluble ferric oxide

ironsironsulfide (pyriulfide (pyritte)e) (slightly soluble) Ferrous carbonate (siderite)(slightly soluble) Ferrous carbonate (siderite)

MainlyMainly

Mn Mn in soil as manganese dioxide (insoluble) in water in soil as manganese dioxide (insoluble) in water containing COcontaining CO22

Under anaerobic cond. Under anaerobic cond. : oxidation state changes: oxidation state changes ΙV ΙV ΙΙ ΙΙ

These changes These changes occur occur due to biological rxnsdue to biological rxns: : 1) 1) GG.W..W. containing Fe, Mn containing Fe, Mn low D.O high COlow D.O high CO22

in the form Fein the form Fe2+2+ , Mn , Mn2+2+ High COHigh CO22 bacterial oxidation of organic matter. bacterial oxidation of organic matter.Absence of D.O Absence of D.O anaerobic cond. anaerobic cond.

2) 2) Wells producing good water Wells producing good water change to poor change to poor qualityquality in time. What is the reason? in time. What is the reason?

Organic wastes discharge aroundOrganic wastes discharge aroundanaerobic anaerobic condconditions occur itions occur in soil.in soil.

3) 3) In surface waters (reservoirs) anaerobic condIn surface waters (reservoirs) anaerobic conditions itions occur ioccur in hypolimnionn hypolimnion..

Fe,Mn reFe,Mn releasedleased f fromrom bottom bottom mud. Distributed to the mud. Distributed to the whole lake during fwhole lake during fall overturn.all overturn.

4) 4) Mn (IV) , Fe (III) stable oxidation states for aerobic.Mn (IV) , Fe (III) stable oxidation states for aerobic.Reduced to soluble Mn(II) , Fe(II) under highly Reduced to soluble Mn(II) , Fe(II) under highly

anaerobicanaerobic conditions. conditions.

G.WG.W.. contain CO contain CO2 2

FeCOFeCO33 + CO + CO2 2 + H+ H22O O Fe Fe2+2+ + 2HCO + 2HCO33--

like dissolution of calcium and magnesium carbonates like dissolution of calcium and magnesium carbonates

More problems w/ insoluble ferric compounds.More problems w/ insoluble ferric compounds.

Under anaerobic (reducing) condition :Under anaerobic (reducing) condition : FeFe3+3+ Fe Fe2+2+ (ferric) (ferrous)(ferric) (ferrous)

5) 5) Certain bacteria use Fe (III) and Mn(IV) as electron Certain bacteria use Fe (III) and Mn(IV) as electron acceptoracceptor. (?). (?)

When OWhen O2 2 containing water injected into G.W for containing water injected into G.W for recharge recharge soluble Fe content may increase. soluble Fe content may increase.

OO2 2 consumed by pyriteconsumed by pyrite FeSFeS22 l leeading to anaerobic ading to anaerobic condconditions againitions again

2FeS2FeS2 2 + 7O + 7O22 + 2H + 2H22O O 2Fe 2Fe2+2+ + 42SO + 42SO442-2- + 4H + 4H++

Environmental SignificanceEnvironmental Significance No harmful affect in drinking waterNo harmful affect in drinking water When exposed to air When exposed to air become turbidbecome turbid, , formform colloidal colloidal

precipitants precipitants unaccepted aestheticalyunaccepted aestheticaly oxidation rate oxidation rate not rapid not rapid

Form stable complexes with humic substances Form stable complexes with humic substances more more resistant to oxidation resistant to oxidation

Interfere with laundering.Interfere with laundering.

Environmental SignificanceEnvironmental Significance

Difficulties in distribution sys. Difficulties in distribution sys. growth growth of ironof iron bacteria bacteria ImpImpaartsrts taste taste to water to water

Fe: 0.3 mg/LFe: 0.3 mg/L SMCL SMCL Mn: 0.05 mg/LMn: 0.05 mg/L

Measurement of Iron Measurement of Iron (Phenanthroline Method)(Phenanthroline Method)

Interferences : PhosphateInterferences : Phosphate Heavy metals Heavy metals

1,10 phenonthroline combines with Fe1,10 phenonthroline combines with Fe2+ 2+ to form to form complex ion orange in red color complex ion orange in red color

Color produced confirms Beer’s Law Color produced confirms Beer’s Law Visual Visual PhotometricPhotometric comparison comparison

Phenanthroline MethodPhenanthroline MethodSample exposed to atmSample exposed to atmospfere contains ospfere contains FeFe2+ 2+ , Fe , Fe3+3+ , ppt of , ppt of

ferric hydroxide.ferric hydroxide.AllAll iron iron must be in soluble form must be in soluble form

HCl is usedHCl is used FeFe((OH)OH)33 + 3 H + 3 H++ Fe Fe3+ 3+ + 3 H+ 3 H22OO

11,,10 phenonthroline 10 phenonthroline specific for measuring Fe(II) specific for measuring Fe(II)FeFe3+3+ is reduced to is reduced to FeFe2+ 2+

HHydroxylamydroxylamineine is used is used as reducing agent as reducing agent 4Fe(III) + 2 NH4Fe(III) + 2 NH22OH OH 4Fe(II) + N 4Fe(II) + N22O + HO + H22O + 4 HO + 4 H++

3 molecules of 1,10 3 molecules of 1,10 phenantrhroline phenantrhroline complexcomplex with each with each FeFe2+2+

Manganese measurement Manganese measurement Colorimetric Colorimetric method method depend upon oxidation of depend upon oxidation of

Mn to Mn to VII VII forms highly colored permanganete ion forms highly colored permanganete ion

Obeys Beer’s Law Obeys Beer’s Law Visual or photometric Visual or photometric comparisoncomparison

AASAAS

ICPICP

Manganese measurement Manganese measurement (Persulphate Method)(Persulphate Method)

Ammonium persulphate Ammonium persulphate oxidizing agent oxidizing agent

ClCl-- interference interference: B: Bececaause of reducing action in acid medium.use of reducing action in acid medium.use Hguse Hg2+2+ for interference. Hfor interference. HgClgCl22 complex complex is formedis formed

AgAg2+ 2+ is used as is used as catalystcatalyst

Oxidation of Mn in lower vOxidation of Mn in lower vaalencelence to to permanganete by persulfate.permanganete by persulfate. AgAg++

2Mn2Mn2+2++5S+5S22OO882- 2- +8H+8H22OO 2MnO 2MnO44

- - +10SO+10SO442- 2- +16H+16H++

(permanganete colored)(permanganete colored)