6-Chemical Parameter 3-revised.pptx

8/10/2019 6-Chemical Parameter 3-revised.pptx

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DR. ATIKAHPOSTGRADUATE CHEMISTRY PROGRAMME

MATHEMATICAL AND NATURAL SCIENCES FACULTYBRAWIJAYA UNIVERSITY

2012

12/11/2014 16-chemical parameter measurement-3


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Scope and Application

1. This method is applicable to the analysis of drinking,surface and saline waters, domestic and industrialwastes.

2. The method is capable of measuring phenolicmaterials at the 5 m g/L level when the colored endproduct is extracted and concentrated in a solventphase using phenol as a standard.

3. The method is capable of measuring phenolic

materials that contain more than 50 m g/L in theaqueous phase (without solvent extraction) usingphenol as a standard.

4. It is not possible to use this method to differentiatebetween different kinds of phenols.



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Phenolic materials react with 4-

aminoantipyrine in the presence of

potassium ferricyanide at a pH of 10 to form

a stable reddish-brown colored antipyrinedye.

The amount of color produced is a function

of the concentration of phenolic material.



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OH N

H3C-N C = O

H3C - C C- NH2

N

H3C-N C = O

H3C - C C- N=

+

K3Fe(CN)6

pH 10

Phenol

4-Aminoantipyrin

Yellowis red



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1. For most samples a preliminary distillation isrequired to remove interfering materials.

2. Color response of phenolic materials with 4-aminoantipyrine is not the same for all compounds.

3. Because phenolic type wastes usually contain avariety of phenols, it is not possible to duplicate amixture of phenols to be used as a standard.

4. For this reason phenol has been selected as astandard and any color produced by the reaction of

other phenolic compounds is reported as phenol.5. This value will represent the minimum

concentration of phenolic compounds present inthe sample.



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Biological degradation is inhibited by the

addition of 1 g/L of copper sulfate to the

sample and acidification to a pH of less than

4 with phosphoric acid. The sample should be kept at 4C and

analyzed within 24 hours after collection.



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1. Interferences from sulfur compounds areeliminated by acidifying the sample to a pH ofless than 4 with H3PO4and aerating briefly bystirring and adding CuSO4

2. Oxidizing agents such as chlorine, detected bythe liberation of iodine upon acidification inthe presence of potassium iodide, areremoved immediately after sampling by theaddition of an excess of ferrous ammonium

sulfate3. If chlorine is not removed, the phenolic

compounds may be partially oxidized and theresults may be low.



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1. Measure 500 mL sample into a beaker. Lower

the pH to approximately 4 with 1 + 9 H3PO4

(7.1), add 5 mL CuSO4solution (7.2) and

transfer to the distillation apparatus. Omit

adding H PO and CuSO4if sample waspreserved as described.

2. Distill 450 mL of sample, stop the distillation,

and when boiling ceases add 50 mL of warm

distilled water to the flask and resumedistillation until 500 mL have been collected.

3. If the distillate is turbid, filter through a

prewashed membrane filter.



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Prepare the following standards in 100 mL

volumetric flasks.

mL of working solution

A

Conc. F g/L

0 0.0

0.5 50.0

1.0 100.0

2.0 200.0

5.0 500.0

8.0 800.0

10.0 1000.0



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To 100 mL of distillate or an aliquot diluted

to 100 mL and/or standards, add 2 mL of

buffer solution (7.3) and mix. The pH of the

sample and standards should be 10 0.2. Add 2.0 mL aminoantipyrine solution (7.4)

and mix.

Add 2.0 mL potassium ferricyanide solution

(7.5) and mix. After 15 minutes read absorbance at 510 nm.



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Using working solution B (7.8), prepare the

following standards.

Standards may be prepared by pipetting the

required volumes into the separatory funnelsand diluting to 500 mL with distilled water.



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mL of working solution B Conc. F g/L

0.0 0.0

3.0 6.0

5.0 10.0

10.0 20.0

20.0 40.0

25.0 50.0



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Place 500 mL of distillate or an aliquot diluted to 500 mLin a separatory funnel. The sample should not containmore than 25 F g phenol.

To sample and standards add 10 mL of buffer solution (7.3)and mix. The pH should be 10.2.

Add 3.0 mL aminoantipyrine solution (7.4) and mix. Add 3.0 mL potassium ferricyanide solution (7.5) and mix.

After three minutes, extract with 25 mL of chloroform(7.9). Shake the separatory funnel at least 10 times, letCHCl settle, shake again 10 3 times and let chloroformsettle again. Vent chloroform fumes into hood.

Filter chloroform extracts through filter paper. Do not addmore chloroform. Carry out filtration in a hood. Dispose ofchloroform in environmentally acceptable manner.

Read the absorbance of the samples and standards againstthe blank at 460 nm.



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10.1 Using the extraction procedure for

concentration of color, six laboratories

analyzed samples at concentrations of 9.6,

48.3, and 93.5 F g/L. Standard deviations

were O.99, 3.1 and 4.2 F g/L, respectively.

Using the direct photometric procedure, six

laboratories analyzed samples at

concentrations of 4.7, 48.2 and 97.0 mg/L.Standard deviations were 0.18, 0.48 and 1.58

mg/L, respectively.



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This method is applicable to the determination of

cyanides amenable to chlorination in drinking,

surface and saline waters, domestic and

industrial wastes.

The titration procedure is used for measuring

concentrations of cyanide exceeding 1 mg/L after

removal of the cyanides amenable to

chlorination.

Below this level the colorimetric determination is

used.



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A portion of the sample is chlorinated at a pH

> 11 to decompose the cyanide.

Cyanide levels in the chlorinated sample are

then determined by the method for Cyanide,Total, in this manual.

Cyanides amenable to chlorination are then

calculated by difference.



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1. Two sample aliquots are required to

determine cyanides amenable to

chlorination. To one 500 mL aliquot or a

volume diluted to 500 ml, add calcium

hypochlorite solution (3.1) dropwise while

agitating and maintaining the pH between

11 and 12 with sodium hydroxide (3.2).



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The initial reaction product of alkaline

chlorination is the very toxic gas cyanogen

chloride; therefore, it is recommended that

this reaction be performed in a hood.

For convenience, the sample may be agitated

in a 1 liter beaker by means of a magnetic

stirring device.



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2. Test for residual chlorine with KI-starch paper

(3.4) and maintain this excess for one hour,

continuing agitation. A distinct blue color on the

test paper indicates a sufficient chlorine level. If

necessary, add additional hypochlorite solution.

3. After one hour, add 0.5 g portions of ascorbic

acid (3.3) until KI-starch paper shows no residual

chlorine. Add an additional 0.5 g of ascorbic acid

to insure the presence of excess reducing agent.4. Test for total cyanide in both the chlorinated

and unchlorinated aliquots as in the method

Cyanide, Total, in this manual.



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1.1 This method is applicable to the determination

of cyanide in drinking, surface and saline waters,

domestic and industrial wastes.

1.2 The titration procedure using silver nitrate

with p-dimethylamino-benzal-rhodanine

indicator is used for measuring concentrations of

cyanide exceeding 1 mg/L (0.25 mg/250 mL of

absorbing liquid).

1.3 The colorimetric procedure is used for

concentrations below 1 mg/L of cyanide and is

sensitive to about 0.02 mg/L.



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1. The cyanide as hydrocyanic acid (HCN) is released from cyanidecomplexes by means of, a reflux-distillation operation andabsorbed in a scrubber containing sodium hydroxide solution. Thecyanide ion in the absorbing solution is then determined byvolumetric titration or colorimetrically.

2. In the colorimetric measurement the cyanide is converted to

cyanogen chloride, CNCl, by reaction with chloramine-T at a pHless than 8 without hydrolyzing to the cyanate. After the reactionis complete, color is formed on the addition of pyridine-pyrazolone or pyridine-barbituric acid reagent. The absorbance isread at 620 nm when using pyridine-pyrazolone or 578 nm forpyridine-barbituric acid. To obtain colors of comparable intensity,it is essential to have the same salt content in both the sampleand the standards.

3. The titrimetric measurement uses standard solution of silvernitrate to titrate cyanide in the presence of a silver sensitiveindicator.



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1. Cyanide is defined as cyanide ion and complexcyanides converted to hydrocyanic acid (HCN) by

reaction in a reflux system of a mineral acid in thepresence of magnesium ion.

2. Oxidizing agents such as chlorine decompose most ofthe cyanides. Test a drop of the sample with potassiumiodide-starch test paper (KI-starch paper); a blue color

indicates the need for treatment. Add ascorbic acid, afew crystals at a time, until a drop of sample producesno color on the indicator paper. Then add an additional0.06 g of ascorbic acid for each liter of sample volume.

3. Samples must be preserved with 2 mL of 10 N sodiumhydroxide per liter of sample (pH 2 > or = 12) at the

time of collection.4. Samples should be analyzed as rapidly as possible after

collection. If storage is required, the samples should bestored in a refrigerator or in an ice chest filled withwater and ice to maintain temperature at 4C.



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1. Interferences are eliminated or reduced byusing the distillation procedure described inProcedure 8.1, 8.2 and 8.3.

2. Sulfides adversely affect the colorimetric andtitration procedures. Samples that containhydrogen sulfide, metal sulfides or othercompounds that may produce hydrogen sulfideduring the distillation should be distilled by theoptional procedure described in Procedure 8.2.The apparatus for this procedure is shown in

Figure 3.3. Fatty acids will distill and form soaps under the

alkaline titration conditions, making the endpoint almost impossible to detect.



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4. High results may be obtained for samples

that contain nitrate and/or nitrite.

During the distillation nitrate and nitrite will

form nitrous acid which will react with someorganic compounds to form oximes.

These compounds formed will decompose

under test conditions to generate HCN.

The interference of nitrate and nitrite iseliminated by pretreatment with sulfamic

acid.



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Acidify the sample with acetic acid (1 + 9) to pH 6.0 to7.0.

Caution: This operation must be performed in the hoodand the sample left there until it can be made alkalineagain after the extraction has been performed.

Extract with iso-octane, hexane, or chloroform(preference in order named) with a solvent volumeequal to 20% of the sample volume.

One extraction is usually adequate to reduce the fattyacids below the interference level.

Avoid multiple extractions or a long contact time at low

pH in order to keep the loss of HCN at a minimum.When the extraction is completed, immediately raisethe pH of the sample to above 12 with NaOH solution.



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In a single laboratory (EMSL), using mixed

industrial and domestic waste samples at

concentrations of 0.06, 0.13, 0.28 and 0.62

mg/L CN, the standard deviations were

0.005, 0.007, 0.031 and 0.094, respectively.

In a single laboratory (EMSL), using mixed

industrial and domestic waste samples at

concentrations of 0.28 and 0.62 mg/L CN,recoveries were 85% and 102%, respectively.



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Scope and Application1.1 This method is applicable to the

measurement of total and dissolved sulfides

in drinking, surface and saline waters,

domestic and industrial wastes.1.2 Acid insoluble sulfides are not measured by

this method. Copper sulfide is the only

common sulfide in this class.

1.3 The method is suitable for themeasurement of sulfide in concentrations up

to 20 mg/L.



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Sulfide reacts with dimethyl-p-phenylenediamine(p-aminodimethyl aniline) in the presence offerric chloride to produce methylene blue, a dyewhich is measured at a wavelength maximum of

625 nm.Comments

Samples must be taken with a minimum ofaeration.

Sulfide may be volatilized by aeration and anyoxygen inadvertently added to the sample mayconvert the sulfide to an unmeasurable form.

Dissolved oxygen should not be present in anywater used to dilute standards.



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Color development

Transfer 7.5 mL of sample to each of twomatched test tubes using a special widetipped pipet or filling to a mark on the testtubes.

To tube A add 0.5 mL amine-sulfuric acidreagent (5.2) and 0.15 mL (3 drops) FeClsolution (5.3).

Mix immediately by inverting the tube only

once. To tube B add 0.5 mL 1 + 1 H2SO4(5.4) and

0.15 mL (3 drops) FeCl2solution (5.3) andmix.



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Color will develop in tube A in the presence

of sulfide. Color development is usually

complete in about 1 minute, but a longer

time is often required for the fading of the

initial pink color.

Wait 3 to 5 minutes.

Add 1.6 mL (NH ) HPO solution (5.5) to each

tube.Wait 3 to 5 minutes and make color

comparisons. If zinc acetate was used wait at

least 10 minutes before making comparison.



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Visual

Add methylene blue solution 1 (5.6) and/or II

(5.7) (depending on sulfide concentration

and accuracy desired) dropwise to tube B(6.1.4) until the color matches that

developed in the first tube.

If the concentration exceeds 20 mg/L, repeat

6.2.1.1 using a portion of the sample dilutedto one tenth.



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Why Determine Fluoride in Water?

removal of excess fluoride in water supply;

addition of fluoride to optimum levels (1.0

mg/L) in drinking water supplies for dentalhealth;

for assessing contamination levels in

aluminum processing plants



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Immigration information on high levels ofdisfiguration of the teeth or mottled enamel(dental fluorosis) found among certainimmigrants from areas of Europe lead to the

suspicion that the problem must be local; Information about high incidence of mottled

enamel among USA natives largely from cities inthe Great Plains and Rocky Mountains Statesconfirms that the problem is local;

In 1930, the mystery was solved when highlevels of fluoride (> 1.0 mg/L) were correlatedwith high incidence of mottled enamel amongUSA natives



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1938 information was presented which

demonstrated that dental caries is less

prevalent among mottled enamel patients;

for and many other studies, it was established

that approximately 1 mg/L of fluoride ion is

desirable in public waters for optimal dental

health;

at decreasing levels, dental caries becomes a

serious problem and at increasing levels dentalfluorosis become problematic.



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One of the major industrial uses involve the

compound cryolite (Na3AlF6) as a molten solventfor Al2O3in the electrolytic production ofaluminum;

At the operating temperature, the moltencryolite develops considerable vapor pressure

which escapes to the atmosphere through theexhaust system; the gaseous fluoride condenses to form smoke and

much of the particulate matter settles on vegetationand the soil in the area;

can result in considerable bone and dental damage tolivestock and humans e.g. has occurred in certainareas of USA.

problem can be minimized by the use of electrostaticprecipitation units in the exhaust system.



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Fluorides in drinking water are supplemented

the the forms of: NaF, CaF2, HF, Na2SiF, H2SiF6

or (NH4)2SiF6

all these forms of fluoride can be determinedby any method that is sensitive to the

fluoride ion e.g.

SiF62-+ 3H2O 6F

-+ 6H++ SiO32-



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Summary of Method

Following distillation to remove

interferences, the sample is treated with the

SPADNS reagent. The loss of color resulting from the reaction

of fluoride with the zirconyl- SPADNS dye is a

function of the fluoride concentration.



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This method is applicable to the

measurement of fluoride in drinking, surface,

and saline waters, domestic and industrial

wastes.

The method covers the range from 0.1 to

about 1.4 mg/L F. This range may be

extended to 1000 mg/L using the Fluoride Ion

Selective Electrode Method (EPA 340.2) afterdistillation.



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SPADNS = sodium 2-(parasulfophenylazo)-1,8-

dihydroxy-3,6-naphthalene disulfonate

Formation of pre-formed color:

Zr2+

+ SPADNS Zr-SPADNS complexcolorless

Zr-SPADNS complex + 6F- ZrF62-+ SPADNS

bright color



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The SPADNS reagent is more tolerant of

interfering materials than other accepted

fluoride reagents.

Reference to Table 414:1, p 388, StandardMethods for the Examination of Waters and

Wastewaters, 14th Edition, will help the

analyst decide if distillation is required.


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12/11/20146-chemical parameter measurement-3 41


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The addition of the highly colored SPADNS

reagent must be done with utmost accuracy

because the fluoride concentration is

measured as a difference of absorbance in

the blank and the sample.

A small error in reagent addition is the most

prominent source of error in this test.

Care must be taken to avoid overheating theflask above the level of the solution.



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On a sample containing 0.83 mg/L F with nointerferences, 53 analysts using the Bellackdistillation and the SPADNS reagent obtained a meanof 0.81 mg/L F with a standard deviation of 0.089mg/L.

On a sample containing 0.57 mg/L F (with 200 mg/L

SO and 10 mg/L Al as 4 interferences) 53 analystsusing the Bellack distillation obtained a mean of 0.60mg/L F with a standard deviation of 0.103 mg/L.

On a sample containing 0.68 mg/L F (with 200 mg/LSO , 2 mg/L Al and 2.5 4 mg/L [Na(PO ) ] as

interferences), 53 analysts using the Bellackdistillation 3 6 obtained a mean of 0.72 mg/L F with astandard deviation of 0.092 mg/L. (AnalyticalReference Service, Sample 11 I-B water, Fluoride,August, 1961.)



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Uses fluoride sensitive membrane electrodesmade from lanthanum (III) fluoride singlecrystal doped with trace amounts ofeuropium (II) fluoride o serve as the

electrical barrier between the inside of theelectrode and the sample.

The supporting electrode inside theelectrode is NaCl/NaF at O.1M.

Potential is developed across the crystal(junction) when a solution of differentconcentration of fluoride is in contact withthe outside of the crystal.



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Interferences include OH-, Cl-, etc;Total ion

strength buffer(TISB) is added to standards

and samples to cancel out the ionic effects;

and expanded scale pH Meter.

Once the electrode is standardized,

measurement is very simple.

Improved sensitivity over the SPADNS Method

especially whencyclohyxlenediaminetetraacetic acid (CDTA)

is often added to TISB to free complexd

fluoride ions for improved method accuracy.



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Alizarin

Formation of pre-formed color:

Zr2++ Alizarin Zr- Alizarin complex

Yellow reddish color

Zr- Alizarin complex + 6F ZrF62-+ Alizarin

reddish color Yellow



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Monitoring supplementation of fluoride ion in

drinking water sources for adequate dental

health;

Monitoring fluorides for removal in areaswhere natural abundance exceeds US EPA

MCL of4mg/L.

Monitoring compliance in industrial sites.



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Sources of Chloride in the Environment

Solvolysis of minerals containing chlorides by water;most chlorides salts are soluble in water;

Salt crystals blown in-landform seas and oceans by

wind; Undercurrent flow of salt water into fresh water

reservoirs e.g. estimated that salt water flows up to 80km inland at Hudson river in New York, has limited theCitys used of the river as a drinking water source.

Human waste containing about 6g/person/day resultsin increase in chloride in waste by about 1 mg/L);

Industrial waste especially where brine waste from oilprocessing is allowed. e.g. Ohio river valley)



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Chlorides as used as tracers by environmental engineersfor the following reasons:

presence is not visually detectable

normal and non-toxic constituent of water

concentration used do not significantly altered or

changed the back ground to toxic levels not altered by biological activities

it is easily measured

where applicable, chloride has been replaced witorganic dyes which can be easily detected at trace

levels; however, for areas where soil-to-water ratio is high,

halides (especially bromide or chloride) is still in usebecause they are not retarded by adsorption to soilparticles.



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At reasonable concentration, chloride is not

harmful to humans;

at > 250 mg/L in drinking water it imparts

objectionable salty taste,hence limit of 250mg/L

is set for public drinking water supply;

limited to 250mg/L where where high

concentration of salts at irrigation root zones of

makes it difficult for crops to assimilate water

due to osmosis



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1. Volumetric

Argentiometric or Mohrs Method

Chloride (Titrimetric, Mercuric Nitrate)

Inorganic, Non-Metallics: Chlorine, TotalResidual, Titrimetric, Amperometric

2. Instrumental Methods

A. Spectrophotometric

Chloride (Colorimetric, Automated

Ferricyanide AAI)



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Chloride (Colorimetric, Automated

Ferricyanide AAII)

Inorganic, Non-Metallics: Chloride,

Colorimetric, Automated Ferricyanide, AA I

: Inorganic, Non-Metallics: Chloride,

Colorimetric, Automated Ferricyanide, AA II



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Chlorine, Total Residual, Titrimetric, Back,

Iodometric

Chlorine, Total Residual, Titrimetric,

Iodometric

Chlorine, Total Residual, Titrimetric, DPD-FAS

Chlorine, Total Residual,Spectrophotometric,

DPD



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Summary of Method

Water adjusted to pH 8.3 is titrated with

silver nitrate solution in the presence of

potassium chromate indicator.

The end point is indicated by persistence of

the orange-silver chromate color.



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This method is intended primarily for oxygen

bomb combustates or other waters where the

chloride content is 5 mg/L or more and

where interferences such as color or high

concentrations of heavy metal ions render

Method impracticable.



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Cl + AgNO3 AgCl(s) + NO3 +K2CrO4

0.0141N ksp= 3 x 1010

2Ag++ CrO42- Ag2CrO4

reddish-brown ppt

Calibration: use high purity NaCl



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titrate blank to correct for or indicator error

use uniform sample size;

keep pH 7 - 8;

pH8, AgOH precipitates use same quantity if indicator to avoid "too-

soon" or "not-soon-enough" color changes leadingto inadequate blank correction;typical value =0.2-0.4mL

Cl-(mg/L) = (mL AgNO3 - blank) x 0.5x1000

mL sample



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Bromide, iodide, and sulfide are titrated along

with the chloride.

Orthophosphate and polyphosphate interfere if

present in concentrations greater than 250 and

25 mg/L, respectively.

Sulfite and objectionable color or turbidity must

be eliminated.

Compounds that precipitate at pH 8.3 (certain

hydroxides) may cause error by occlusion.Residual sodium carbonate from the bomb

combustion may react with silver nitrate to

produce the precipitate, silver carbonate.



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This competitive reaction may interfere with

the visual detection of the end point.

To remove carbonate from the test solution,

add small quantities of sulfuric acid followed

by agitation.



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Average value

(g/g)

Repeatability

(g/g)

Reproducibility

(g/g)

500 180 355

1,000

360

710

1,500 540 1,065

2,000 720 1,420

2,500 900 1,775

3,000 1,080 2,130


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Amount

Expected (g/g)Amount

Found

(g/g)

Bias; (g/g) Percentbias

320 645 325 +102

480 665 185 +39

920 855 -65 -7

1,498 1,515 17 +1

1,527 1,369 -158 -10

3,029 2,570 -460 -15

3,045 2,683 -362 -12


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For determining the best selection of water

source for public or industrial use.

To determine the type of desalting

technique most suitable for the water supply.

For monitoring industrial disposal to

safeguard receiving waters such as rivers and

lakes.



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THANK [email protected]

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