1

1. PURPOSE:

The purpose of this experiment is to become familiar with the principles of calorimetric analysis and to determine the iron content of an unknown sample and to show the use of calibration curves in spectrophotometric analysis.

2. PROCEDURE:

1. We pipette 2, 6, 10, 20, 30 and 50 mL standard iron solution into 100 mL volumetric flasks.

2. We add 1 mL hydroxylamine hydrochloride solution to each flask.

3. We add 10 mL 1.10 phenantroline solution, make up to the volume, and mix well.

4. We prepare a blank solution using distilled water by adding the same reagents (steps 2 and 3) except the standard iron solution.

5. We prepare our unknown solution using unknown sample given, by adding the same reagents (step 2 and 3).

6. We wait for a few minutes the color development.

7. We measure the absorbance of each solution at 510 nm using the blank solution.

8. We plot these results as absorbance versus concentration to obtain the calibration curve.

9. We measure the absorbance of unknown sample and determine its concentration using the calibration curve.

3. THEORY:

Colorimetric analysis is based on the change in the intensity of the color of a solution with variations in concentrations. Colorimetric methods represent the simplest form of absorption analysis. The human eye is used to compare the color of the sample solution with a set of standards until a match is found. An increase in sensitivity and accuracy results when a spectrophotometer is used to measure the color intensity.

2

Figure 1: Spectrophotometer (Skoog et. all, p.565)

Basically a spectrophotometer is an instrument which measures the fraction (I/I0) of an incident beam of light (I0) which is transmitted (I) by a sample of a particular wavelength. The instrument consists of five fundamental components:

1. A light source which emits light with a wavelength range about 350 to 1000mn.

2. A monochromator which selects a particular wavelength of light and sends it to the sample cell with an intensity of I0.

3. The sample cell to hold the solution being analyzed.

4. A detector which measures the intensity of the transmitted light (I) from the sample cell.

5. A meter which indicates the intensity of the transmitted light.

There are two ways to measure the difference in intensity of the light beam. One is the percent transmittance, %T, which is defined as:

%T =I/I0 *100%

The other method is in terms of absorbance which is defined by:

A= log I0 / I= k*C

Where k: constant for particular solution

3

C: concentration of solution

I0: intensity of light entering solution

I: intensity of light leaving solution

T: transmittance of solution

A: absorbance, or optical density of solution

Absorbance is related to the concentration according to the Beer-Law:

A=abC Where A: absorbance a: the extinction coefficient (M-1cm-1) b: the solution path length (cm) C: the concentration (moles litre-1)

In this experiment, you will analyze for iron by reacting iron +II with o-phenanthroline to form an orange-red complex ion according to the following equation:

Figure 2: The reaction of phenanthroline and ferrous (Vogel, p.345)

Because we are starting with an Fe+3 solution and in order to be quantitive all of the iron must be reduced from Fe+3 and Fe+2 by the use of an excess of hydroxylamine hydrochloride.

4 Fe+3 + 2NH2OHHCI 4 Fe+2 + N2O + 4H+ + H2O

4

4. DATA ANALYSIS AND CALCULATIONS

Standard Fe Solution (mL) Absorbance at 510 nm2 0.0336 0.12210 0.19420 0.36830 0.56450 0.969Unknown 0.299

1 mL Fe = 0.01 mg Fe

2 mL Fe = 0.02 mg Fe

(0.02 mg /100 mL)*(1000 mL/1 L) = 0.2 mg/ L

Standard Fe Solution (mg/ L) Absorbance at 510 nm0.2 0.0330.6 0.1221 0.1942 0.3683 0.5645 0.969Unknown 0.299

0 1 2 3 4 5 60

0.2

0.4

0.6

0.8

1

1.2

f(x) = 0.191543147208122 xR² = 0.99961815886304

Concentration vs. Absorbance

Series2Linear (Series2)

Standard Fe solution concentration (mg/L)

Ab

sorb

ance

at

510

nm

5

y= 0.1915x , y=0.299

0.299 = 0.1915x x=1.56 mg/ L

1.56*100/8 = 19.5 mg / L (unknown)

DISCUSSION AND CONCLUSION:

2. Alternative procedures for analyzing of iron in water:

1. Colorimetric method

2. Gravimetric method

Three methods of colorimetric iron analysis are used. The 1, 10- Phenanthroline Method is the best-known test for iron. The Fe2+ procedure uses Ferrous Iron Reagent Powder containing 1, 10 Phenanthroline as an indicator. Total iron determination or analysis uses FerroVer Iron Reagent. FerroVer Iron Reagent contains 1, 10-Phenanthroline, combined with a reducing agent, to convert all but the most resistant forms of iron present in the sample to Fe2+.

The FerroZine Method for total iron is more than twice as sensitive as the 1, 10-Phenanthroline Method. Researchers at Hach have patented a process to manufacture high purity FerroZine Iron Reagent, ideal for iron measurement, in economical quantities. FerroZine is highly specific for iron, forms an intensely-colored stable complex and performs in the pH range of 3–7.5. The FerroZine Method requires boiling to dissolve rust.

The TPTZ Method for total iron has the advantages of simplicity, sensitivity and freedom from common interferences. Iron in the sample, including precipitated or suspended iron such as rust, is converted to Fe2+ by a reducing agent. A highly colored Fe2+-TPTZ complex is formed.

FerroZine methodVery low concentrations of iron can be determined using an ultra-sensitive iron indicator, FerroZine Iron Reagent, 3-(2-pyridyl)-5, 6-bis (4-phensylsulfonic acid)-1, 2, 4-triazine, monosodium salt. FerroZine Iron Reagent also can be used to analyze samples containing magnetite (black iron oxide) or ferrites. The test is performed by adding a solution of FerroZine Iron Reagent to the water sample. The sample is thereby buffered to a pH of 3.5 and a purple-colored complex directly proportional to the iron concentration is formed. A reducing agent is included to convert any Fe3+ to Fe2+ (which forms the colored complex).

TPTZ methodTPTZ, 2, 4, 6 -tripyridyl-s-triazine, reacts with Fe2+ to form a deep blue-purple color. Reducing agents are added to convert iron in the sample to the Fe2+ form. TPTZ, reducing agents and pH buffers are combined in one simple reagent— TPTZ Iron Reagent Powder Pillows.

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Titration methodThe Titration Method is intended for high iron concentrations, such as oil-field water determinations. In this method the iron present in the sample is oxidized to Fe3+ by an oxidizing agent. The Fe3+ is then detected with sulfosalicylic acid, which forms a wine red complex with Fe3+. The solution is titrated with TitraVer (EDTA) to a colorless to yellow end point. A buffer is added to stabilize the Fe3+.( URL 1)Gravimetric Determination of Iron

– Determine constant weight of the crucibles

– Oxidation of iron sample

– Precipitation of iron hydroxide

– Ignition of iron hydroxide to iron oxide

– Determine constant weight of the crucibles plus iron oxide

– Calculation of iron in the sample (URL 2)

3. Corrosion process:

Fe -----> Current ------> Fe++

          Or           Acid

           H          /   Fe++--(O) -->O2--->Fe2O3

      \          Fe3O4

           H

(URL 3)

Corrosion and Metal Solubility Control

Control of corrosion and metal solubility is perhaps the single most cost-effective method for preventing iron contamination. Significant benefits include:

Reduction of contaminants at our taps Cost savings by extending the useful life of water mains and service lines Energy savings from transporting water more easily through smoother, non-

corroded pipes Reduced water losses resulting from leaking or broken mains or other plumbing

Corrosion control is used to manage the acidity, alkalinity, and other water qualities that affect pipes and equipment used to transport water. By controlling these factors, the chance of iron leaching into our water supply is reduced.

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Conventional treatments can also be used to remove secondary contaminants, such as iron, from our drinking water. These treatments include coagulation/flocculation, filtration, aeration, and the use of granular activated carbon. Nonconventional treatments include distillation, reverse osmosis, and electrodialysis. However, these are fairly expensive technologies and may be impractical for smaller systems. Nontreatment options include blending water from the principal source with uncontaminated water from an alternative source. (URL 4)

Why is Corrosion Control important?

1. Corrosion can cause failure of pipes, tanks, etc.2. Corrosion puts impurities in the water which must be removed.3. Corrosion is a costly item for all water/wastewater plants, lines that conduct water,

and tanks.4. Corrosion can cause a reduction or loss of electrical conductivity which can cause

the plant to operate inefficiently or fail.

( URL 3)

1.

Tablo 14.5: Sektör: Kimya Sanayi (Boya, Boya Hammadde ve Yardımcı Madde Üretimi ve Benzerleri)

PARAMETRE BİRİMKOMPOZİT NUMUNE

2 SAATLİK

KOMPOZİT NUMUNE

24 SAATLİKKİMYASAL OKSİJEN İHTİYACI (KOİ)

(mg/L) 200 150

KROM (Cr+6) (mg/L) 0.5 0.3KADMİYUM (Cd) (mg/L) - 0. 2ÇİNKO (Zn) (mg/L) 4 3TOPLAM KROM (mg/L) 2 1KURŞUN (Pb) (mg/L) 2 1DEMİR (Fe) (mg/L) 30TOPLAM SİYANÜR (CNˉ) (mg/L) 2 1BALIK BİYODENEYİ (ZSF) - 6 3pH - 6-9 6-9

TABLO 1: KITAİÇİ SU KAYNAKLARININ SINIFLARINA GÖRE KALİTE KRİTERLERİ

SU KALİTE SINIFLARISU KALİTE PARAMETRELERİ I II III IVA) Fiziksel ve inorganik- kimyasal Parametreler 1) Sıcaklık (oC) 25 25 30 > 30 2) pH 6.5-8.5 6.5-8.5 6.0-9.0 6.0-9.0

dışında

8

TABLO 1: KITAİÇİ SU KAYNAKLARININ SINIFLARINA GÖRE KALİTE KRİTERLERİ

SU KALİTE SINIFLARISU KALİTE PARAMETRELERİ I II III IV 3) Çözünmüş oksijen (mg O2/L)a 8 6 3 < 3 4) Oksijen doygunluğu (%)a 90 70 40 < 40 5) Klorür iyonu (mg Cl‾/L) 25 200 400b > 400 6) Sülfat iyonu (mg SO4

=/L) 200 200 400 > 400 7) Amonyum azotu (mg NH4

+-N/L) 0.2c 1c 2c > 2 8) Nitrit azotu (mg NO2‾-N/L) 0.002 0.01 0.05 > 0.05 9) Nitrat azotu (mg NO3‾-N/L) 5 10 20 > 20 10) Toplam fosfor (mg P/L) 0.02 0.16 0.65 > 0.65 11) Toplam çözünmüş madde (mg/L) 500 1500 5000 > 5000 12) Renk (Pt-Co birimi) 5 50 300 > 300 13) Sodyum (mg Na+/L) 125 125 250 > 250B) Organik parametreler 1) Kimyasal oksijen ihtiyacı (KOİ) (mg/L)

25 50 70 > 70

2) Biyolojik oksijen ihtiyacı (BOİ) (mg/L)

4 8 20 > 20

3) Toplam organik karbon (mg/L) 5 8 12 > 12 4) Toplam kjeldahl-azotu (mg/L) 0.5 1.5 5 > 5 5) Yağ ve gres (mg/L) 0.02 0.3 0.5 > 0.5 6) Metilen mavisi ile reaksiyon veren yüzey aktif maddeleri (MBAS) (mg/L)

0.05 0.2 1 > 1.5

7) Fenolik maddeler (uçucu) (mg/L) 0.002 0.01 0.1 > 0.1 8) Mineral yağlar ve türevleri (mg/L) 0.02 0.1 0.5 > 0.5 9) Toplam pestisid (mg/L) 0.001 0.01 0.1 > 0.1C) İnorganik kirlenme parametrelerid

1) Civa (μg Hg/L) 0.1 0.5 2 > 2 2) Kadmiyum (μg Cd/L) 3 5 10 > 10 3) Kurşun (μg Pb/L) 10 20 50 > 50 4) Arsenik (μg As/L) 20 50 100 > 100 5) Bakır (μg Cu/L) 20 50 200 > 200 6) Krom (toplam) (μg Cr/L) 20 50 200 > 200

7) Krom (μg Cr+6/L)Ölçülmeyecek

kadar az20 50 > 50

8) Kobalt (μg Co/L) 10 20 200 > 200 9) Nikel (μg Ni/L) 20 50 200 > 200 10) Çinko (μg Zn/L) 200 500 2000 > 2000 11) Siyanür (toplam) (μg CN/L) 10 50 100 > 100 12) Florür (μg F‾/L) 1000 1500 2000 > 2000 13) Serbest klor (μg Cl2/L) 10 10 50 > 50 14) Sülfür (μg S=/L) 2 2 10 > 10 15) Demir (μg Fe/L) 300 1000 5000 > 5000 16) Mangan (μg Mn/L) 100 500 3000 > 3000 17) Bor (μg B/L) 1000e 1000e 1000e > 1000 18) Selenyum (μg Se/L) 10 10 20 > 20 19) Baryum (μg Ba/L) 1000 2000 2000 > 2000

9

TABLO 1: KITAİÇİ SU KAYNAKLARININ SINIFLARINA GÖRE KALİTE KRİTERLERİ

SU KALİTE SINIFLARISU KALİTE PARAMETRELERİ I II III IV 20) Alüminyum (mg Al/L) 0.3 0.3 1 > 1 21) Radyoaktivite (pCi/L) alfa-aktivitesi 1 10 10 > 10 beta-aktivitesi 10 100 100 > 100D) Bakteriyolojik parametreler 1) Fekal koliform(EMS/100 mL) 10 200 2000 > 2000 2) Toplam koliform (EMS/100 mL) 100 20000 100000 > 100000

Tablo 15.15: Sektör: Metal Sanayii (Alüminyum Hariç Olmak Üzere Demir Dışı Metal Üretimi)

PARAMETRE BİRİMKOMPOZİT NUMUNE

2 SAATLİK

KOMPOZİT NUMUNE

24 SAATLİKKİMYASAL OKSİJEN İHTİYACI (KOİ)

(mg/L) 100 50

ASKIDA KATI MADDE (AKM) (mg/L) 125 100KADMİYUM (Cd)* (mg/L) 0.5 -YAĞ VE GRES (mg/L) 20 -CİVA (Hg)* (mg/L) - 0.05ÇİNKO (Zn)* (mg/L) 5 -KURŞUN (Pb)* (mg/L) 2 -BAKIR (Cu)* (mg/L) 2 -DEMİR (Fe)* (mg/L) 10 -TOPLAM KROM* (mg/L) 2 -KROM (Cr+6)* (mg/L) 0.5 -ARSENİK* (mg/L) 0.1 -NİKEL (Ni)* (mg/L) 3 -TOPLAM SİYANÜR (CNˉ)* (mg/L) 0.1pH - 6-9 6-9

TABLO 19: KARIŞIK ENDÜSTRİYEL ATIK SULARIN ALICI ORTAMA DEŞARJ STANDARTLARIKÜÇÜK VE BÜYÜK ORGANİZE SANAYİ BÖLGELERİ VE SEKTÖR BELİRLEMESİ YAPILAMAYAN DİĞER SANAYİLER)

PARAMETRE BİRİMKOMPOZİT NUMUNE

2 SAATLİK

KOMPOZİT NUMUNE

24 SAATLİKKİMYASAL OKSİJEN İHTİYACI (KOİ)

(mg/L) 400 300

ASKIDA KATI MADDE (AKM) (mg/L) 200 100YAĞ VE GRES (mg/L) 20 10

10

TOPLAM FOSFOR (mg/L) 2 1TOPLAM KROM (mg/L) 2 1KROM (Cr+6) (mg/L) 0.5 0.5KURŞUN (Pb) (mg/L) 2 1TOPLAM SİYANÜR (CNˉ) (mg/L) 1 0.5KADMİYUM (Cd) (mg/L) 0.1 -DEMİR (Fe) (mg/L) 10 -FLORÜR (Fˉ) (mg/L) 15 -BAKIR (Cu) (mg/L) 3 -ÇİNKO (Zn) (mg/L) 5 -CİVA (Hg) (mg/L) - 0.05SÜLFAT (SO4 ) (mg/L) 1500 1500TOPLAM KJELDAHL-AZOTU (mg/L) 20 15BALIK BİYODENEYİ (ZSF) - 10 10pH - 6-9 6-9 

(URL5 )

Our sample can be discharged chemical industry. Our result is above the water quality standards.

REFERENCES:

1.URL 1. Iron for water and seawater, retrieved 10 December 2012 from, http://www.hach.com/asset-get.download-en.jsa?id=7639984186

2.URL 2. Gravimetry, retrieved 10 December 2012 from, http://www.br.inter.edu/dirlist/Ciencia_Tecnologia/juan_negron/QUIMICA%203320/Gravimetry.pdf )

3. URL 3.Corrosion Control in a Water/ Wastewater Plant, retrieved 10 December 2012 from, http://water.me.vccs.edu/concepts/ccontrol.html

4.URL4.Iron, retrieved 10 December 2012 from, http://www.epa.gov/nrmrl/wswrd/cr/corr_res_iron.html

5.URL 5. Su Kirlliği Kontrolü Yönetmeliği, retrieved 10 December 2012 from, www.ibb.gov.tr/tr- TR/kurumsal/Birimler/.../sukirliligiyonetmelik.doc

6. Skoog, A.D., and West, D.M., Fundamentals of Analytical Chemistry, 2nd Ed., Holt, Rinehart and Winston Inc., 1969, p.565

7. Vogel, A textbook of Quantitative Inorganic Analysis, 3rd Ed., pp.294-784