Determination of chlorine and iodine in water essay

It is based on measurement of the absorption, the red DPD colour complex in a photometer or the colour intensity by visual comparison of the colour with a scale of standards that is regularly calibrated.

Determination of chlorine and iodine in water essay

A standard instrument for the group parameter AOX adsorbable organic halogens was used for the combustion. The halides formed were trapped in an alkaline solution and analysed by capillary zone electrophoresis. The method described enabled determination of sub-ppb concentrations of the group parameters AOC1, AOBr and AOI adsorbable organic chlorine, bromine and iodine, respectively.

Analysis of rain and snow collected at different sites in Europe showed that organochlorines were responsible for the major part of the AOX content in all samples collected.

Organically bound bromine was found in sub-ppb concentrations in all of the samples, whereas organic iodine was detected in only two of the samples. An efficient enrichment step adsorption on activated carbon ensures that a very wide range of organohalogens are measured.

A halogen-specific detection method microcoulometric titration with silver ions ensures that all chloride, bromide and iodide formed upon combustion of the enriched organic matter is included in the AOX value.

Gas chromatographic studies of specific organohalogens have revealed the presence of several chlorinated compounds [7, 8], but it has also been demonstrated that compounds of unknown structure are responsible for the major part of the AOX content in precipitation [7- 9].

This raises the question of the relative distribution of chlorine, bromine and iodine in the organic matter that has not yet been identified. These investigators subjected samples of snow to neutron activation analysis to determine the group parameters AOC1 and AOBr adsorbable organic chlorine and bromine, respectively.

However, the results of the study called for further investigations for several reasons: Moreover, it is not certain to what extent the analysed snow samples were representative of precipitation in general. The present study had two objectives: Snow samples were collected after individual snowfalls by pushing 5-L polypropylene jars into fresh, friable loose snow, avoiding the snow that was close to the ice on lakes or the ground.


Information about sample types and sampling sites is summarised in Table 1. Chemieals Sodium chromate pro analysis was obtained from Mallinckrodt, 1-octanesulphonic acid sodium salt monohydrate puriss was from Fluka.

Sodium molybdate pro analysis and acetonitrile for chromatography came from Merck. The left part Of Figure 1 illustrates the different steps invoked in this analysis. It is normally prescribed that 50 mg of activated carbon is employed to adsorb organics present in mL of sample [ 12].

However, because the content of organic matter in precipitation is generally low, we used only 10 mg of activated carbon and mL of sample. All analyses for AOX were carried out in duplicate.

Then, the recovery of individual halogens from 10 mg of activated carbon was studied by separately analysing standard solutions of p- dichlorobenzene 10 p. Finally, several aliquots of real precipitation samples were analysed by using 10 and 50 mg, respectively, of activated carbon in the adsorption step.

Capillary zone electrophoresis of halides Halides recovered from combustion of organic matter in the AOX analyser were separated on a Waters Quanta capillary zone electrophoresis CZE system.

The CZE instrument was furnished with a 61 cm fused silica capillary internal diameter 75 p. Quantification was accomplished by on-line indirect UV detection at ran. The CZE conditions were as follows: Acetonitrile was added to the carder electrolyte buffer to improve the separation of the analysed anions [13, 14], and octanesulphonate was added to the sample to achieve isotachophoretic conditions during the electrokinetic sample introduction [15, 16].

The impact of sample conductivity on the detection limits of the studied halides was determined by analysing standard solutions of chloride, bromide and iodide 5, 10 or 20 ppb of each of the halides in Concentrations of 0, 2.

Dechlorination and H2O2

The repeatability of the CZE analysis was studied by analysing separate aliquots of a standard solution of chloride, bromide and iodide 50 ppb of each halide in Nine aliquots of the standard solution and one blank The amount of activated carbon used to enrich organics from a precipitation sample was kept to a minimum 10 mg to prevent sulphate originating from combustion of the activated carbon from interfering with the CZE analysis of halides.

Calibration curves for quantification were established by analysing standard solutions of chloride, bromide and iodide 10, 25, 50 or ppb of each anion in l0 -4 M KOH. Two types of blank samples were used in the CZE analysis: Quantification was based on standard addition analysis.

Chloride was not analysed at the ppb level, because the first ionisation potential of chlorine is too close to that of argon. RESULTS Analytical procedures Capillary zone electrophoresis of standard solutions of Cl - Br and I- The electropherograms in Figure 2 show that chloride, bromide and iodide were easily detected when dissolved to a concentration of 10 ppb in Furthermore, the detector response was linear over a wide range of concentrations Figure 3.

The detection limits achieved at different conductivity levels are shown in Table 2, and the results of a repeatability test are presented in Table 3.

The peak that is not marked in B was caused by an unknown anion. Recovery of organically bound halogens in the AOX analysis Analysis of different aliquots of a standard solution ofp-dichlorobenzene and p-dibromobenzene mL sample containing 10 ppb of each halide showed that the amount of carbon used in the adsorption step of the AOX analysis could be decreased from 50 to 10 mg without any significant loss of organically bound halogens.Sea water suitability: yes: Detectible with PF yes # Swimming pool tests: $/box of 50 strips: This swimming pool test consists of test sticks for the semi-quantitative determination of free chlorine, alkalinity and the pH value of swimming pool water.

for the determination of total chlorine in water. with liberation of free iodine. Instantaneous reduction of the iodine by a known excess of thiosulfate standard solution previously added to the solution.

Determination of chlorine and iodine in water essay

Water quality - Determination of free chlorine and total chlorine - Part 3: Iodometric titration method for the determination of. The concentrations of chlorine, bromine, iodine, and uranium were determined in tektites, obsidians, and impact glasses by neutron activation. The chlorine as HOCl and OCl- is referred to as free available chlorine.

This is the form of chlorine typically found in cooling water circuits, industrial bleaching systems, and . New Spectrophotometric method for the determination of trace residual chlorine in spectrophotometric reagent for the determination of chlorine in water sample [14, 15, 22,].

Ready kits are available for this and extensively used. [23]. Besides, bromine, iodine and bromoamines interfere by giving the same colored product with DPD. After the break point,free chlorine (hypochlorous acid plus hypochlorite) is the dominant disinfectant.

Typically, the free chlorine residual is adjusted to maintain a minimum level of mg/L Cl 2 throughout the distribution system. The importance of break-point chlorination lies in the control of taste and odor and increased germicidal efficiency.

Chlorine Test Papers - Swimming Pools