"This paper not to be cited without prior reference to the author"

International Council for theExploration of the Sea

C.H. 1975/E: 15Fisheries ImprovementCommittee

Problems in ozone determination in sea-water============================================

by

H. RosenthaI and G. HinzBiologische Anstalt Helgoland,

Zentrale Hamburg,Fed. Rep. Germany

INTRODUCTION

Ozone has been found useful in a number of applications related

to human activities since its discovery by SCHÖNBEIN in 1840. In

water sterilization and tertiary sewage treatment, ozone was

virtually replaced by chlorine during the first half of this

century because of higher production costs of ozone. In more

recent years interest is returning to ozone as an effective agent

in water pollution control. New and more efficient production

methods have been developed that. reduce operational costs.

Findings.of HUBBS (1930) and DOUDOROFF and KATZ (1950) tended to

discourage the use of ozone as a means of water treatment for

aquaculture purpose. BENOIT and ~1ATLIN (1966) were the first to

·, -,2

state thata reexamination of ozone could beuseful as a means for

disease control in'American fish hatcheries. vfuile aquaculturists

showed no interest in ozone during the last decade, ozonization

has become a most beneficial standard method for water treatment

of home aquaria.From their own experience theauthors believe

that ozone can play an important role in water treatment re-use

systems (ROSENTHAL, ~1974) .(ROSENTHALand WESTERNHAGEN, 1975).

CO~ON METHODS FOR OZONE DETERMINATION

The impetus to select a suitable procedure for the determination

of ozone dissolved in sea water arose from the requirement to

evaluate the effectiveness of ozone application in sea-water

treatment units. In fish culture units it is of great importance

to control residual ozone levels because of its high toxicity.

Quantitative determinations of ozone have been troublesome, both

in air and in aqueous solutions. Among the most important methods

for low-level determination of ozone in air are the starch-iodine

method (THORP, 1940), .the ph~nolphthalein oxidation reaction

(HAAGEN-SMIT and BRUNELLE, 1958), the long-path ultraviolet ad­

so~ption method (RENZETTI, 1957), the sodiom diphenylaminesulphonate

reaction (BOVEE and rrOBINSON, 1961), and the peroxy-isocyanate

method (LAYTON et al., 1970).

Problems of determination of ozone in water arise from its rapid

decomposition and its interaction with other ions in solution

(INGOLS et al., 1959; SULZER,.1958; KOPPE and HUHLE 1965; HOFf1AN. ' , .,,'.:.

and STERN, 1969 a, b). as shown in .Fig •. 1 speed of ozone decompo-

f .••

- 3 -

Table'1: Nethods of ozone determinations (m0c'!-ified after. ' ,

. ROSENTHAL, 1974) ~ ,

',.

f.1ethod Remarks, ....

References

reaction with potassium neutral or slightlyiodide and back tritation acidic,tritationof iodine wi~hNa2 82,°3 of iodine'

ZEHENDER (1952)

Manganese-oxidationand colour reactionwith oithotolidine-

r-~++ --+ Mn-4:'++(Spectrophotometricdetermination at '

_ 440m}l; 5-20;..tM/l

ZEHENDER and,STUMM (1953)SULZER "(1958

Oxidation of Lenco­crystal violet

Redox.indicator,colorometric procedureat a wave length of

, 592 ~-in.aci~icsolution (sub~ppm

< levels)• l' '"

LAYTON. andKINMAN (1970

KINr.IAN (1975)

Spectrophotometryin distilled.water(visible, region)

Oxidative decolorationof indigo-sulfonate

Reaction of ozonewith potassium iodide

typical absorptionband at" 260 m)l« 0.4 pM/I)

phosphate-buffer(pH 6.85) .

colorometricdetermination of theliberated iodine withstarch

" ALDER and HILL(1950)KILPATRICK et al.(1956),.

,DORTA-SCHAEPPI ,- ,'andTRADWELL (1949). . ~

tAAWSON (1953)

Ozone reaction withMn (lI) diphosphatecomplex~ Mn (III)disphosphate complex

Reaction of ozone withpotassium iodide

.. , "

Reaction'with potassiumiodide and colorimetricdetermination of iodine

Cr (III) as catalyst;·o determination inp~esence of chlorine, HOFr-IANN andchlorine dioxide, . STERN (1969 a,b)hypochlorite , chlorate,perchlorate

"'ANNER (1971)

Itwo modifiedapplications for low 'level (0.01-0.30 ppm) SHECHTER.(1973al,ld h~gh level .. deter- ,m~nat~on, (0.30-2. OOppm -- : .-

Reaction with potassiumiodide and colorometric Stoichiometrydetermination of iodine ," PARRY and HERN(1973)

sition in Iresh water is highly dependent on the pH OI the medium.

(ZEHENDER, 1952; ZEHENDER and STill1M, 1953; STUMM, 1954).

The usual methods Ior the determination OI ozone in water are

iodine titration (ZEHENDER and. STUMM, 1953; INGOLS et al, 1959;

RAWSON, 1953), the colorometric Mangan-o-Tolidin-method (STUMM,1956),

the Aminodimethylaniline-method (PALIN, 1953), the Indigo-method

(DORTA-SCHAEPPI and TRADWELL, 1949) and the Tetramethyldiamino­

diphenylmethan-method (KOPPE and MUHLE,1965). Some Iurther methods _

are summarized in Table 1.

The method developed by DORTA-SCHAEPPI and TRADlfflLL (1949) using

Indicocarmin (which is oxidized to isatin) is highly sensitive but

is not speciIic enough to be employed Ior determination OI residual

ozone in polluted water because it also reacts with nitrate. Most

of the methods described in the literature are inappropriate Ior

determining ozone in the presence of chlorine and chlorine-compounds.

EXPERIMENTS ON ozorm DETEFU1INATION IN SEA-WATER

Selection of method.

The following criteria were employed to select a method which

satisIies our requirements:

a) the method should allow ozone determination in the

presence of high chloride, nitrate and sulphate concentra­

tions•.

b) the methodshould be sufficiently sensetive to detect

residual ozone" down to levels of 0.1 ppm

- 5 -

c) the method should be simple, easyto handle, and not

time consuming.

After a thorough survey of the literature, the method developed by

ZEHENDER (1952) and ZEHEWDER and ST~f (1953) was selected and

modified (see also KINMAN, 1975) • The reaction of ozone and

iodide is based on the following equation:

03 + 2 I (-) + 2 H+-7 I 2 + H20 + 02.-The liberated iodine willusually be determined by back titration

with.thiosulphate:

EÄ--perimental procedure.

The exPerimental design is shown in Fig. 2. Ambient air is

thoroughly dried passing through two 200 ml bottles (a and b)

," containing CaCl2 and Silica gel.

The air was ozonized in an electrical discharge ozonizer (c)

(Typ IV, Fa. Sander) at a flow rate of 200 l/h resulting in a

total ozone production of approximately 700 mg 03/h (Fig. 3).

Ozone containing air was bubbled through a water column of a

500 ml sampIe (e) for different periods of time (i.e. 30, 60,

120, 300, 600 sec). Immediately after ozonization a 100 ml sampIe

of the treated water was poured into a jar containing a mixture

of potassium-iodide solution (1 mlj 0. 1 normal)'and acetate­

buf~er (10 IDlj pH = 4.62). The liberated iodine was titrated with

sodium thiosulphate (0.01 n). The endpoint of tritation was

-- 6 -

deterrnined by l1leasuring -the redox-potential \~'ith a Plntin-Calomel~

electrode. Some minor modifications of the methods described by

ZEiffiNDER (1952) were m~de in order to meet pB requirements for

iodine titration in sea-\vater. Fig. 4 shovlS an example of a typical

tritation curve.

'I'ne stoichiolfletry of the ozone-iodide reaction is based on the

fore, thc amount of ozone can becalculated by the expression

48 x 0.79 x (ml) x CF) =316.4 mg 03/1

~lare ml is the amount of thiosulphate titrated in millilitres and

F a fac-cor correcting the sample volume to 1 liter.

Table 2 illustrates the results obtained from ozone determination

trials when clean (filtered) sea-water and polluted sea water of

d.ifferent o1'ganic loads \'ras aerated vii th ozone containing air for

different periods of time. Polluted water vlaS obtained from the

outlet of the fish-rearing tanks.

Th~ results indicate that detection of ozone in sea-water i8

possible down to levels of about 0.002 mg/l, but the error of tlle

method remains high (about 10 to 15%). Nevertheless, we find this

accuracy sufficient to determine retention time of sea-viater in

- 7 -

thc storage tanks and thus to ensure complete decomposition o~

, ozone before the water enters the fish tanks.

Nothing is known about the total amount 01' ozone absorbed by sea­

vfater because a considerable amount 01' the introduced gas may have

escapcd \'lith the air bubbled through the water colurnn. From our

determination trials it has become obvious that most 01' theozone

rcactn and/or is decomposedimmediately after introduction into'

tt the water. Residual ozone levels found in water 01' low initial

organic load (KI1l:l04 value : "12.5 mg/I) are about1% and 7% 01'

the total amount 01' ozone gas introduced irito the medium when

ozonization lasts for 0.5 and 5.0 minutes, respectively. In sea­

water Hith high organic loads, ozone levels reached after a five

minutes treatment period ,.,ere 0.156 01' the total amount 01' ozone

introduced. Thus, over short periods (minutes), intensive ozoni­

zation 01' sea-water with ahigh organic load will not lead to

detrimental residual ozone levels which may damage the fishes in

.the tanl{s.

Decomposition of residual ozone in relatively unpolluted water

(1011104 value : 4ft mg/I) is still rapid compared \'lith values

obtained in destilled water. About 855ö'and 50% 01' the ozone level

reached 'I[ithin a 30 second treatmen t period remained after one and

rive minutes,respectively.

At present nothing is known on interference of other ions \iith the

ozone determination method employed except the fact that cllloride,

nitrite und nitrate ions do not significantly effect the reaction

between iodide and ozone in solution.

r-------------------------- ---- - - -

- 8-

DISCUSSION

Thc major problems in using the iodine titration method arise from

the fact thatthe amount of iodine liberated whcn ozone is added

to iodide solutions is markedly dependenton pH. After INGOLS et al

(1~59) twice as much iodine was liberated at pH 2 than at pH 9.

BYERS and SALTZMAN (1959) obtained an increased ratio in the

I- - / O~ in similar investigations. They assumed that at pH 7 the::; .,:;

ra~io of molecules of iodine to molecules ofozone was 1 : 1 tt(SALTZMAN and GILBERT, 1959). Our results are based on this

assumption in order to get a first approximation. We are weIl

a\iUre thatthe results obtained by BOYD et al (1970) give a·

stoichiometry for. neutral pH of 1.53 molecules of sodine liberated

per molecule of ozone absorbed. PARRY and HERN (1973) have shown

thut the oxidation of iodide to iodate is also thermodynamically

feasible,especially at higher ozone concentrations. On the .other

hand HODGESON et al (1971) and KOPCZYNSKI and BUFALINI (197-1)

have reaffirmed the stoichiometry for the reaction as 1. : 1.

Using redox potential measurements as indication of titration

endpoint rIas several advantages compared to the starch-iodide

procedure which is believed to give aprecision of about ± 1%.

At low ozone levels thisprocedure of determination of ozone in

wa~er begins to show significant error when th~ re~eased iodine

in loss than about 2.0 mg/I. An iodine concelltration of 2.0 mg/I

in neutral solution i5 equivalent to an ozone cencentration of

about 0.4 mg/I. Thus· the starch-iodide procedure has a large error

when ozone concentration is less than about 1.0 mg/I (KINTvIAN, 1975).

- 9 -

Kil~N (1975) recommends amperometric titration for measuring

low ozone residuals in water. Commercial equipment: is available

for measuring 0 to 1.00 mg/l of ozone in water directly by means

of a copper-gold electrode combination.

Further experiments are planned to exaIIiine the applicability of

this method of ozone determination in sea-water. We also intend

to investigate whether or not some chlorine is liberated by

e ozonization in sea-water. This could be done by the method developed

by HOFMAN and STERN (1969 a, b) where ozone reacts with the

manganese (lI) diphosphate complex in acidic media , to form the

manganese (III) diphosphate complex which reac~s. with o-tolidine.

The method allows the determination of ozone in the presence of

chlorine, chlorine dioxid, hypochlorite, chlorite, chlorate and

perchlorate.

- 10 -

1.0 pH=7'",

0.8

0.6

[03] t 0.41+ log

[°3]0 0.2

0

-0.2

- 0.40 6 12 18

Time (min,)

Fig. 1: Decomposition of ozone in aqueous solution in relationto pR value of the medium (after STUMM, 1954)

--fFig. 2: Experimental design used in ozone determination trials

A and B ~ Air drying tubes (200 ml volume each);C ~ ozonizer; D = water bath (20°C); E = sampIe jar(500 ml);F = Voltmeter

- 11 -

._----,----- ---------- .---- ----

1000----...c

""'"(J)

E-ua>g 500-0oL-0-

a>coNo 04----r--.--------,.--.,.-----,---

100 .. 300 500

Air flow (l/h)

Fig. 3: Ozone production (mgO.~/h) of the ozonizer used(Typ IV, Fa. Sander) 1n relation to air flow rate.

--------

mV

.- - - - - - - - - - - - - - - - - ~ - - - I

••w

140

100

60

20

o Q1 0.2 0.3 ml

Fig. 4: Typical mV-curve foriodine-thiosulphate titrationusing a Pt-Calomel-Redox electrode.

- 12 -

Table 2: Residual ozone concentrations (mg/I) in relation to theorganic load of the water treated, 'the duration ofozonization (in brackets: total amount of ozone introducedinto the medium), and decomposition \'iithin 0.5; 1.0 and5.0 minutes af~er treatment •

. Temperature 20 C; salinity 32 0/00 ; initial pH = 7.95-8.14;n = number of determinations; x = meanj s- = error of the .mean.' x

~. duration of30 " 60 " 300 "~ozonization

(sec) (5.81 mg 03) (11 .65 mg 03) (23.3 re°3)or~aniC~

lo~d of the time after treatmentmedium (~m 04 val~ (min)

0.5 1.0 5.0

12.5 n 5 2 2± 0.121 - - 0.216 1.248

si 0.020

44.0 n 10 9 8- 0.041 0.035 0.02'1x - -

s- 0.005 0.004 0.002~ ..J\.

105.0 n 3 2 9

- 0 - - 0 0.028xs- 0.002x

,

ALDER, H.G. andRILL, .G.R.1950

BErmIT, R. F., andrrJ.A~LIN, N.A.1966 '

BOVEE, H.H. andROBINSON, R.J.1961 ,

LITERATURE CITED

'Thc Kinetics and mechnismof.hydroxidc ion catalyzed ozone' " _decomposition in aqueous solution.J .Am.Chem.Soc. 72: 1884-1886, ','

~ ~ , ~ .. , .

,Control of Saprolegpia 6ri·eggs 'of'rainbow trout (Salmo gairdneri) withozone.Trans.Amer.Fish.Soc. 22 (4)~ 430-432

Sodium Diphenylaminesultonate as'. an analytical reagent tor ozone.Anal.Chem. 33 (8): 1115-1118

·e

•

BOYD, A.W., WILLIS,' C.and CYR, R.1970

DYERS, D.H. and, SALTZI1AN, B.1959

'DOUDOROFF,'P. andKATZ, 101.1950 '

DORrA-SCHAEPPE, A. andTREADWELL, \'1. D•1949

HAAGEI'J'':'SNIT, A.J. andBRUNELLE, M.J.1953

HODGESON, J .A.,DANNGARDNER, 'R.E. , ,MERTIN, B.E. andREH:1E, R.A.197'1.' -

, HOFI1AN, P., andSTERN, P.1969 "

- .HOFI1ANN, P. andSTEIlN,' P.1969

HUBES, .C.L.1930

Ncw determination of stoichiometryof the iodometrie method for ozoneanalysis at pR 7.0. . . ,.'~al.Chem. 42 (6): 670~672','·,··

. : Determination of ozone in air byneutral and alkaline iodide procedures.

: Anal.Chem.Ser. 21: 93-101 .. ,

Critical review of literature on thetoxicity of industrial wastes and.their components to fish. . . .'I. Alkalies, acids and inorganic gases.Sewage Ind. Wastes 22 (11): 1432-1453

, -Ober eine kolorimetrische Bestimmungvon hochverdünntem'Ozon'in 'Sauer-stoff. . . ,..Helv.Chem. Acta 32; 356-364

Thc'application of phenolphthalen­reagent to atmospheric oxidant analysis.J.Air.Pollut.- 1: 51~59

Stoichiometry in the ventral iodometrie. procedure for ozone by gas-phase-titration with nitric oxide.~al.Ghem. 43 (8): 1123-1126

Photometrischc-Ozonbestimmung beim, Vorhandensein der Chlorverbindungen.Anal~Chim. Acta ~:149-155

Photometrische Bestimmung niedrigerOzonkonzentrationen in Wässern.Anal.Chim. Acta ~: 113-120-

The high toxicity of nascent oxygen.Phy~iol.Zool. 2 (4): 441-460

INGOLS, R.S., FETNER, W.H.and EBEHHARDT, \'l.H.

e

1959

KILPATRICK, M.L.,IffiRRICK, C.C. andKILPATRICK, M. .1956 .

Determination of ozone in·[;olution.Adv. Chem. Ser. ~: 102-107

The deeomposition of ozone in aqueoussolution. .J. Am.ehem.So:. 78: 1784-'1789

eSome observations on stoiehiometry ofiodometrie analysis of ozone at pH 7.0.Anal. ehern. 43 (8): 1126-1127

Analysis of ozone-fundamentalprineiples.Proc.1st Intern.Symp. on ozone forWater and waste water treatment,pp 56-68 .(ivaterbury, Conneetieut/ Intern.Ozone Inst.)

KOPCZYNSKI, S.L. undBUFALINI, J.J.1971

KINHAN, R.N.1975

KOPPE, . P. atldHÜHLE, A.1965

Speeifie determination of ozone inwater in the presenee of other oxidants.Z.Analyt.Chem. ~ (4): 241-256

LAYTON, R.F. andKINNAN, R.N.1970

A ne\v analytieal method for ozone.In: National speeialty Conferenee onDisinfeetion, p. 285.(Am.Soe.eivil Engrs.)

LAYTON, R.F., SPATA, D.,anclPIERCE, J.O.1970

HOllitoring ozone in the air by theperoxy/isoeyonate methodeAm.lnd.Hyg.Assoe.J. 31 (6): 738-741

PALIN, A.T.19:;3

PAERY, P. andHERN, D.H.1973

The ozonization of water with special.referenee to eolour removal. .Water,& Water Engng 57: 271-277 .

Stoiehiometry of Ozone-Iodide reaetion:Signifieanee of Iodate formation.Environm. Sei. & Teehnol. 7·(1):65-66

RAWSON, A.E.1953

RENZETTI, N.A.·1957

HOSEN1'HAL, H~1974

Studies in Ozonization. I. The esti­mation of ozone.Water & Water Engn. 57: 56-64

Automatie long-path ultravioletspectrometer for determination ofozone in the atmosphere 'Anal. ehern. 29: 869-874

Seleeted bibliography on ozone, itsbiological effects and technicalapplications.Fish.Res.Bd.Can.,Tech.Rep.No. 456:1-150

...

.t

"

ROSENTHAL, H. andvon WESTERNHAGEN, H.1975

- 15 -

Aspects of water treatment whenrearing fishes in a elosed laboratorysea-water system. .,',ICES, C.M. 1975/E: 13 (Fish ImprovementComm.) 1- " '

SALTZMAN, B.E. andGILBERT, N.1959

SHECHTER, H.1973

e STUMM, W.1954

STtJMr.l, W.1956

SULZER, F.1958

THORP, C.E.1940

WANNER, H.V.1971

,

• ZEHENDE~, F •1952

·ZEHENDER, F. andSTUMM, vf.1953

Iodometrie mierodetermination oforganie oxfdents and ozone.Anal.Chem. 31: 1914-1920

Speetrophotometric method for deter­mination of ozone in aqueous solutions.Water Res. z: 729-739

Der Zerfall von Ozon in wässrigerLösung •

. Helv.Chim.Acta. 37: 773-778

Einige chemische Gesichtspunkte zurWasserozonisierung.Schweiz.Z.Hydrol. 18 (2): 201-207

. . ---Ober das Verhalten wässriger Ozon-lösungen. . .Schweiz.Z.Hydrol. 20 (1): 16-29

Starch iodine method ofozone analysis..Ind.Engng.Chem., Anal.Ed. ~: 209

Unternehmungen in Hallenschwimmbädernmit Ozonierungsanlagen.Areh.Hyg.Bakteriol. 154 (5): 462-473

Ober die Ozonbestimmung bei der Trink­wasseruntersuehung•.

. Mitt.Lebensm.Hyg., Bern~: 144-151

Die Ozonbestimmungbei der Trinkwasser­untersuchung. II. Mitteilung. .Mitt~Lebensm.Hyg., Bern~: 206-213