Basic Knowledge of Ozone

last update： 2019-04-11 11:06:14

Chapter Ⅰ Characteristics of Ozone Ozone (O3 is its molecular formula), is allotrope of oxygen. Its molecular structure is easy to change under normal temperature and normal pressure, swiftly decomposing to be oxygen (O2) and single oxy

Chapter Ⅰ Characteristics of Ozone

Ozone (O3 is its molecular formula), is allotrope of oxygen. Its molecular structure is easy to change under normal temperature and normal pressure, swiftly decomposing to be oxygen (O2) and single oxygen atoms (o) automatically. Ozone is a high-effective oxidant without secondary pollution, since it remains oxygen after it is applied.

Oxygen is obtained from utilized ozone, therefore, ozone is a high-effective and non-secondary pollution oxidant.

It is not easy to store and transport ozone since it is very active, it only can be used upon produced, therefore, ozone generator becomes the representative equipment on ozone technology.

Generating of industrial ozone takes oxygenous gas as its main material. Under the performance of strong electric field, oxygen molecule is opened to re-compose and produce the ozone.

Main physical property of ozone

Molecular formula O3

Molecular weight 48

Smell grass-like smell

Color light blue

Solubility (ml/L water) at 1 atmospheric pressure and 0℃ 640

Stability apt to be decomposed

Density (g/L) at 1 atmospheric pressure and 0℃ 2.144

Threshold value of olfactory sensation 0.02ppm

Allowable safety density in atmosphere 0.1ppm(=0.2mg/m3 air)

Oxidation-reduction potential at 25℃ +2.07v

Chapter Ⅱ Mechanism of Ozone Generation

Oxygen molecule breaks chain to be two oxygen atoms, under the bombardment by high-speed charged particle which is formed under accelerating of high frequency high voltage electric field.

e+O2→2O+e

Oxygen atom and oxygen molecule encounters and produces ozone molecule.

O+O2+M→O3+M

Of which, M is other gas molecule with catalysis.

Chapter Ⅲ Basic structure of ozone generator

It is composed of three parts as following:

1. High frequency high voltage power, which function is to accelerate charged particle (e), so that it can reach the speed to break the chain of oxygen molecule.

2. Ozone generating unit, which function is to break oxygen molecule to be oxygen atoms in the unit’s chamber (or in seamless), and make oxygen atoms and oxygen molecule to combine to be ozone molecule.

3. Auxiliary system, such as cooling device, electric control and protective system, gas source treatment and control system, etc.

Chapter Ⅳ Gas source of ozone generator

Quality of gas source is very important since main material for generating ozone is oxygen.

Ozone generator can be divided into three types as per different gas source, such as oxygen-type ozone generator, air-type ozone generator, and ozone generator with oxygen generator.

Factors in gas source such as oxygen content, temperature, relative humidity (dew point) directly affect output of ozone, of which, under the condition of a certain amount of oxygen content, humidity does most affection to the ozone.

In order to get stable and high quality ozone, it is better to use pure oxygen (industrial use bottled oxygen or liquid oxygen) as gas source.

Difference of ozone generating capacity is large since ozone generator taking air as gas source is affected by environmental condition during operation.

Experiment shows that ozone output from ozone generator using air which is not treated with cool drying and suck drying as gas source in summer will be half or even less than capacity in winter, therefore, the calibration for ozone generator’s output must have explanation about environmental condition.

Even the ozone generator with small oxygen generator, its ozone output also is affected by the environment; output under hot and humid environment in summer is 20% less than that under dry and cold environment in winter.

Indeed, ozone generator using air which is treated with cool drying and suck drying as gas source, its ozone output is more stable, but in summer, since environmental humidity is high, cool drying capacity will be limited more or less, therefore, ozone output from ozone generator taking air as gas source in summer will lower 20-30% than that in winter, and even lower above 40% under above 35℃ room temperature.

Based on our experience, gas source for ozone generator’s common use can be selected as per following principle:

1. Self-made oxygen source (Bottled oxygen can be reach above 98% oxygen content, with -60℃ dew point), which is normally suitable for ozone facility with below 50g/h in enterprises where have higher requirement to ozone output and ozone concentration such as middle-small purified water enterprise, mineral water enterprise and beverage enterprise.

2、Gas source rich of oxygen (oxygen from oxygen generator) can reach above 90% oxygen content, which is normally suitable for ozone facility with above 100g/h in the enterprises where have high requirement to ozone output and ozone density, such as

large purified water plant, mineral water plant, pharmaceutical factory, beverage factory, and food products factory.

Enterprise who is not easy to replace oxygen bottle also can use small size ozone generator with small oxygen generator, such as CFZY-6,CFZY-12 and CFZY-24, etc.

3. Gas source of dry air: The situation where requires low ozone concentration and large ozone output, such as space disinfection, pharmacy workshop disinfection, foot products workshop disinfection, swimming pool, aquiculture, medium water recycle, wastewater treatment, etc, can use gas source of dry air treated by air compressor, filter, cool dryer, and suck dryer, etc.

4. Gas source of untreated direct air: the place where user’s condition is drier or not requires disinfection so strictly, asking for deodorization and mildew removal, can use direct air as gas source or open-type ozone generator.

Authorities Give confirmation To Ozone

Rules from domestic and abroad authorities has already devised positive response to ozone’s effectiveness of disinfection and sterilization and utilization safety.

Legislation of these rules are strictly demonstrated with theory and verified with practice by many experts, with reliability beyond all doubt and incomparable seriousness.

It provides a powerful supporting background to the application and development of ozone technologies.

Herein, introduce epitome of these rules as following:

One. “Technical Norm on Disinfection” from Ministry Of Health gives confirmation to ozone disinfection and sterilization (minute)

Extract from page 162 of “Technical Norm on Disinfection” of 2002 edition of Ministry Of Health,PRCHerein, extract information about ozone from the edition as following:

1. Ozone

1.1. Summary of ozone

Ozone is a strong oxidizing gas under normal temperature, its density is 1,68 (air is 1).

Ozone’s solubility in water is quite low (3%). Its stability is very poor, is able to decompose to be oxygen under normal temperature, therefore, ozone can not be stored by bottle, only can be used promptly upon production on site.

1.2 Scope of application

Ozone is a kind of universal bactericide, it can kill bacteria propagulum, sorus, virus, and epiphyte, etc, and can destroy botulinus toxin. In the scope of disinfection in the hospital, there is mainly following purpose of using ozone:

1) Disinfection to water: disinfection to sewerage in the hospital and water for diagnosis and treat.

2) Disinfection article’s surface: put such articles in airtight box for disinfection as dietetic appliance, physical therapy appliance, food processing appliance, and clothings, etc.

3) Disinfection to air: carry out disinfect to room air when there is nobody in room.

1.3. Method employed

1) Disinfection to water used for diagnosis and treat: normally, ozone content is 0.5mg/L-1.5mg/L, and remained ozone concentration in water keeps 0.1mg/L-0.5mg/L, lasting for 5min-10min. For low quality water, ozone content shall be 3mg/L-6mg/L.

2) Treatment to sewerage in the hospital: technological flow of sewerage treatment with using ozone: feed sewerage into first grade sedimentation basin, after purified, feed it into second grade clarifying tank, after treated, feed it into adjustable tank, and taken into contact tower through sewage water pump, in the tower, it contacts with ozone enough for 10min-15min, then exhausted.

Generally, for a hospital with 300 beds, build up a ozone treatment system with 18t/h-20t/h sewerage treatment capacity, with 15mg/L-20mg/L ozone content, operating for 10min-15min, after treating, the sewerage becomes clear and transparent, without any smell, and total number of bacteria and coliform meets the standard of national sewage discharge.

3) Treatment to swimming-pool water: advantage o using ozone to disinfect swimming-pool water is: it can kill enterococcus and virus, with strong sterilization power and quick speed; it does not cause corrosion and damage to facility of swimming-pool; it

can improve water quality, decolorizes and deodorizes, treated water becomes glittering and translucent, without any pungency to the swimmer.

Its disadvantage is that ozone decomposes quickly in water, with short lasting time for disinfection, is not able to remove the durative pollution.

Normally, it can get perfect disinfection result with 1mg/L-1.7mg/L input amount of ozone and 1min-2min contact time, which can get obvious improvement to water quality. If it is used for circulating water treatment to swimming-pool, input amount of ozone is 2mg/L.

4) Disinfection to air: ozone has function to kill animalcule in air obviously, using 20mg/m3 ozone density, operating for 30min, which killing ratio to natural bacterium can reach above 90%.

If using ozone to disinfect air, it must be carried out in enclosure space, also there is nobody in the space, it only allows people coming in after at least 30min, which can be applied to disinfect air in such sites as operating room, sickroom, asepsis workshop of plant, etc.

5) Surface disinfection

5.1) Use ozone gas to disinfect polluted animalcule on the surface of article, which has function of extermination, but only operating for 60min-120min with 60mg/m3 and relative humidity ≥70% can meet the effect of disinfection.

5.2) Use ozone water to disinfect: it requires to operate for above 60min with ozone concentration＞10mg/L in water.

1.4 Watchful item

1) Ozone is harmful to human, therefore, it is ruled by nation that allowable density of ozone in atmosphere is 0.2mg/m3.

2) Ozone is a kind of strong oxidant, it can damage various articles, much higher density damages much more serious to the article, it can make sheet copper come out green rust, age rubber and change its color, lower its elasticity, so as to being crisp and break, and bleach and fade the fabric, etc. It must be watchful in using.

3) Various factors can affect ozone's sterilization function, including temperature, relative humidity, organic substance, PH, turbidness and chroma of water. So it must give control in using.

Two. “GMP Authentication Directory of Pharmacy Industry” issued by State Food and Drug Administration gives confirmation to ozone’s function of sterilization

“GMP Authentication Directory of Pharmacy Industry” gives following introduction for ozone’s function of sterilization: scientific research indicates that ozone has fearfully powerful function of sterilization.

Ozone's molecular structure is not stable under normal temperature and normal pressure; it quickly decomposes by itself to be oxygen and single oxygen atoms, the latter has very powerful activity, with fearfully powerful function of oxidation to bacteria.

Oxidation of ozone decomposes enzyme, which is what the interior oxidation dextrose of bacteria needs, so as to destroy and kill cell membrane, redundant oxygen atoms will renewedly integrate to be normal oxygen molecule by itself, without any poisonous residue, so it is named as “pollution-free disinfector”.

It not only has fearfully powerful extermination capacity to kinds of bacteria (including hepatitis virus, Escherichia coli, green pyic bacillus, and various bacterium), but also is effective to kill mould.

Three. Oversea authorizations gives appraisal to ozone’s disinfection effect and safety

During the period from 1995 to 1997, several developed countries successively made rules and act on allowing ozone to be applied to foodstuff disinfection.

1. In 1995, Japan classify ozone into “already exit additive list ”

2. In 1995, France opened special approval to ozone rules, agreeing that ozone can blanch fresh and marrow part of fish in aqueous solution.

3. In 1996, Australia foodstuff standard act contained that using ozone as “proper assistant to food processing”.

4. In 1997, Foodstuff and Medicine Administration of USA amended the rules which had been restrictedly used with taken ozone as “food additive” , allowing that ozone can be used in food processing and storage without application, and indicated that in USA, using ozone to deal with foodstuff accorded with rule of “General Regard AS Safe” (namely GRAS).

This indication is the landmark of ozone technology applied to food service industry.

Hereafter, USA carried out many research and report on ozone application in the area of agriculture and food science and technology, using ozone to improve food quality, and ameliorating food processing technology, etc.

It takes great driving impaction to technology advancement of food processing and improvement of food quality for USA as well as many countries.

Correlative Knowledge of Ozone Technology

Chapter Ⅰ Air Source and Oxygen Source

Ozone generator normally uses oxygen in air or pure oxygen in bottle oxygen as raw material gas.

Ozone generator which uses bottled oxygen or small-size oxygen generator as gas source is called as ozone generator with oxygen source.

While that uses air as gas source is called as ozone generator with air source.

Configuration and structure of two kinds of ozone generators are basically same, but ozone output from ozone generator with oxygen source is much more than that from generator with air source though both of them are with same power and size.

Someone thinks that ozone generator with air source is more advantage than that with oxygen source in the scope of equipment price and running cost. This is a misapprehension.

Actually, price of that with air source is higher than that with oxygen source on ozone generator with same output.

Only when required output is very large (more than 100g/h, or even higher than 150g/h), and it is trouble to use bottled oxygen since the running cost is high, ozone generator with oxygen source is considered to be adopted, while ozone generator under 50g/h is more economic with using oxygen source.

If it is not convenient to replace oxygen bottle, ozone generator with oxygen generator also can be selected.

Actually, it is not enough that only use normal compressed air for ozone generator with air source, however, air only can be used after several treatments such as compress, filtrate, cooling dry and absorbing dry, etc.

If the air is not treated, ozone output will be very small with only using compressed air as gas source.（Pls. refer No.4 of Chapter Ⅰ）, of which, the key problem is air contents large amount of moisture, it is rare disadvantage to generate ozone.

Also ozone output changes lot with the temperature and moisture of environment.

Untreated air source ozone generator only can be applied at the area with low requirement.

It is a misguidance that some ozone generating enterprise can have scores of ozone output per hour with air source without deep dry treatment.

For further knowledge about this, please call consultation telephone number: 86-0571-886200093.

Chapter Ⅱ Dew Point and Air’s Moisture Content and Relative Humidity

ozone requires high aridity to air source, air aridity can be indicated with relative humidity or dew point.

Without dry treatment, air contains a mass of water vapour.

Each kg air under 30℃ and 80% relative humidity contains about 22g water vapour.

Upper value of water vapor content in each kg air is called as saturated moisture content.

This value increases with rising of air temperature.

Saturated moisture content under 30℃ is 26g, under 15℃ is 11g, and under 0℃ is 3g, therefore, moisture content in winter air is small, while in summer air, it is higher.

Relative moisture is the specific value of absolute humidity in unsaturated air and saturated absolute humidity under same moisture, indicated with percent.

Higher percent means more humidity.

If there is a mass of unsaturated moisture air, when temperature lowers continuously to some temperature, water vapour in this mass of air will reach to saturation value, and moisture is separated out, that coagulates into “dew”.

This temperature is called as dew temperature of this mass of moisture air, briefly called as “dew point”.

Dew point can indicate moisture content in this mass of air.

If air is dry, its dew point is lower; otherwise, its dew point is higher.

For example: (when ambient temperature is 25℃, and relative humidity is 70%), dew point is +16℃, and moisture content is 12.8 g/m³(when ambient temperature is 0℃, and relative humidity is 50%), dew point is -10℃, and moisture content is 2.4 g/m³.

Dew point of air is -23℃, and moisture content is 0.7 g/m³.

Dew point of air is -45℃, and moisture content is 0.1 g/m³.

Normally, dew point of gas source for ozone generator with air source is required to be below -45℃, so it must use combined drier with enough low dew point of cooling dry and absorbing dry to deal with air.

Chapter Ⅲ Ozone concentrationand Sterilization Consistence in Air

Unit for ozone concentrationin air normally has such two kinds as ppm and mg/m³.

Value of zone density in air is directly relative to extermination ratio to bacteria. Generally, high density comes out high extermination ratio, vice versa. Also it is relative to the relative humidity of environment, extermination is only effective with above 70% relative humidity, while below 40% comes out noneffective extermination.

Ppm is mass ratio of millionth, namely, ozone mass in air in unit volume / air mass.

mg/m³ is ozone content (mg) in each m³ air.

Since air mass changes with temperature, conversion between ppm and mg/m³ is as following:

1ppm=2 mg/m³ (room temperature is 25℃)

1ppm=2.14 mg/m³ (room temperature is 0℃)

Practice shows that when ozone concentration in air reaches 15ppm or 30 mg/m³ and relative humidity is above 70%, its extermination ratio to natural bacteria can reach to above 99%.

Ozone concentration in air can be tested by Model CYQC-1 quick tester of ozone concentration in air from our company.

Chapter Ⅳ Ozone concentration and Sterilization Consistence in Water

Unit of ozone concentration in air normally has such two kinds as mg/L and ppm.

Value of zone density in water is directly relative to extermination ratio to bacteria.

Using ozone in water for disinfection and sterilization has a threshold value. Normally residual ozone concentration in water reaches to 0.3mg/L, it can kill propagulum of bacteria and epiphyte in water in a moment. It is very easy to kill water-solubility virus.

What is called as residual ozone density, that means ozone concentration remained in water after oxidizing organic substance, animalcule and other substance which can be oxidized in the water,

Normally, after ozone is charged into water for 10~30 minutes, the tested density can be considered as residual ozone density.

In summary, normally, pure water after ultra filtration with hollow fiber and filtrating with reverse osmosis membrane, residual ozone concentration reaches to 0.3~0.6 mg/L, and numbers of Escherichia coli and colony all can reach zero index.

Animalcule index is not a big problem if only prevent secondary pollution (such as pollution to bottle and cover).

But it is relatively difficult to kill epiphyte spore and alga spore, which only can be killed with 0.8~1 mg/L ozone density.

But more than 0.6 mg/L ozone concentration may affect water’s taste, so user shall be watchful.

If water is not dealt with filtration, once bacteria combines feculence to be conglomeration, it becomes more difficult to kill them.

Ppm is mass ratio of millionth, namely, ozone mass in air in unit volume / air mass.

mg/L is ozone quality in each litre water.

Without considering the factor that water changes with temperature but density has puny change, it can consider ozone concentration in water is 1ppm=1 mg/L.

Ozone concentration in water can be tested by Model CHYC-1 ozone concentration quick tester from our company.

Chapter Ⅴ Why disinfection effect is better with higher air humidity when using ozone to disinfect air?

Mechanism of ozone disinfection is: oxygen under atom state in ozone has strong oxidation function; it can damage bacteria’s cell wall (membrane), so that the bacteria can not reproduce. It also can saturate cell wall, enter into bacteria’s inside to damage the original enzyme needed by its metabolism.

Ozone is able to enter into bacteria’s cell wall.

When air humidity is high, bacteria's cell wall is able to be intenerated, and ozone easily immerses into cell wall and cell inside, to oxidize and damage bacteria’s original enzyme, and kill bacteria. Therefore, with higher air humidity, effect of ozone sterilization is better.

However, it shall specially point out that open-type ozone generator especially the one with face-along discharge, which gas source is room air, if humidity is high, it will obviously reduce ozone output, so this is a pair of contradictions.

So it is suggested that carrying out air disinfection for workshop with higher humidity, collective outer-facility ozone disinfection plan with Model CFY ozone generator is more reasonable, since this plan can separate disinfection space and ozone generation.

Chapter Ⅵ What is concept of half life of ozone?

Ozone is terribly instable, two ozone molecules can composite to be three oxygen molecules.

O3 + O3 3O2 O3 + O3 collide to be 3O2

In air or in water, original ozone concentration will reduce continuously since ozone composites to be oxygen.

Degression speed of ozone concentration can be indicated with half-life.

Half-life is the required time for ozone concentration reduces to half of original density.

Information from literature normally thinks that half-life of ozone in air under 25℃ is about 30~40; while

Much higher temperature makes O3 more easily composites, and half-life is much shorter.

When water temperature is 4℃, half-life of ozone in water can be up to several days or more. So it is specially paid attention to this problem when add ozone in water in winter. Therefore, it shall add or subtract ozone feeding amount promptly according to room temperature, make reasonable technology plan of ozone disinfection.

Chapter Ⅶ Calculation on ozone feeding amount in air

This chapter requires definite knowledge of engineering mathematics, reader with interest can read in particular, normally it is enough to know about the result.

One. Summary:

Ozone sterilization ratio is relative to ozone density. Page 162 of “Technical Norm on Disinfection” of 2002 edition of Ministry Of Health about ozone sterilization indicates that “using 20mg density of ozone operate for 30min, extermination ratio to natural bacteria can reach to above 90%.” Therefore, ozone with definite density is the key to ensure extermination ratio.

If ozone feeding amount is A, and space volume requiring disinfection and sterilization is V. Ozone concentration in the space is not A/V, since it can not carry out charge in moment, as well as ozone attenuates with time. Therefore ozone concentration changes ceaselessly with time.

When t=0, ozone amount in some sterilization space is mo. With process of time, value of mo reduces ceaselessly. The time when value of mo attenuates to 1/2·mo is known as half-life, defined as τ.

Two. Formula of disintegration coefficient comes out:

Ozone concentrationη= (ozone amount in definite cubage is M) ÷ cubage value

So connection between ozone amount M and ozone concentrationη is very specific.

Ozone amount M is a variable changeable with time, namely M is the function of time t.

M=M（t）

Ozone output M disintegrates with time. Its disintegration speed can be indicated with dM/dt, and direct ratio of ozone output M. Namely

dM /dt=-λM………………………（1）

Of which λ is disintegration coefficient, minus means disintegration.

Figure out the differential eguation (1): dM /dt=-λM

Separate variable: dM /M=-λdt

Both sides integral: : ∫dM /M=∫-λdt

lnM=-λt+clnM=-λt+c

M=e-λt+c=ec·e-λtM=e-λt+c=ec積-λt

令ec=cˊ则 M= cˊ·e-λt

Command ec=cˊthus M= cˊ·e-λt

When t=0, M=MO，initial condition is substituted into the above formula

MO = cˊ·e-λ·0

e-λ·0=1 得cˊ= MO

e-λ·0=1, get cˊ= MO

Get solution: M= MO·e-λt………………………（2）

When command preliminary ozone MO disintegrates to be 1/2·MO, the time is half-life τ, thus τ shall meet:

1/2·MO= MOe-λτ

1/2=e-λτ 1/2=1/eλτ 2=eλτ

λτ=ln2λ

τ=ln2

λ= ln2/τ……………………… (3)

(3)formula is the relation between disintegration coefficient λ and half-life. Half-life of ozone in air is not definitely explained in the literature. Some indicates as one hour, while some indicates as half hour.

Actually, half-life of ozone in air τ changes with air temperature and humidity. We get more believable data through experiment.

Temperature: 35OC 30 OC 26 OC 23.5 OC 20 OC

τ(min) 32 48 65 98 120

If it is under 25 OC room temperature (70% relative humidity), it is correct that half-life is one hour, while under above 35 OC room temperature, half-life is considered as half hour.

Three. Result from computation formula of instant ozone gross in disinfection space

Suppose: (1) Ozone output in extermination space is m, (m=f(t) is function of time)

(2) A is the feeding amount at unit time

(3) λ= ln2/τ is attenuation function, (τ is half-life under some temperature)

Thus there is differential equation: dm=Adt-λmdt…………………(4)

The meaning is: within dt time, increased amount of ozone dm equal to feeding amount of ozone in unit time multiple dt, and minus attenuation amount in dt time.

dm/dt=A-λm

This is a first order linearity non-homogeneous equation, its canonical equation is

yˊ+p(x)y=q(x) yˊ+p(x)y=q(x)

Its general solution is y=e-∫p(x) dx[∫q(x) e∫p(x) dx•dx+c]

To our equation:

y=m p(x)= λ q(x)=A x=t

Substitute it into general solution

Integral gets m=e-λt[∫A• eλt•dt+c1]

Then integral gets m=e-λt[（A/λ）•（eλt+ c2）+c1]

Predigestion: m=e-λt[（A/λ）•eλt+ （A/λ）•c2+c1]

Command （A/λ）•c2+c1=c, so

m=e-λt[（A/λ）•eλt+c]

Predigestion m=A/λ+c e-λt

Substitute it into initial condition: when t=0, without feeding ozone, so m=0

0=A/λ+ c e-λ˙0 (c e-λ˙0=1) &a, mp;n, bsp;

0=A/λ+ c e-λ˙0 (c e-λ˙0=1)

Get c=-A/λ

Substitute it into m=A/λ-（A/λ）e-λt

m=A/λ（1- e-λt）………………（5）

(5) formula namely is computation formula of instant ozone gross used in our plan of sterilization.

Four. Ozone feeding amount and feeding time

Formula (5) m=A/λ（1- e-λt）roundly describes relation among ozone feeding amount, attenuation amount and time. Of which: A is ozone feeding amount in unit time

Λ is disintegration coefficient λ= ln2/τ

Τ is half-life of ozone, which is determined by experiment

m is instant ozone gross in disinfection space, it is function of time m=f(t)

Thus, as long as knowing ozone feeding amount in unit time, half-life of ozone τ, ozone amount can come out in any time t in disinfection space.

Example: for1500m3 disinfection space needs to meet 15PPM，（30mg/ m3） ozone density, ozone gross in space shall be m=1500m3x30 mg/ m3=45g

If using a set of 80g/h ozone generator, namely A=80g/h ozone generator, how much time is required to turn on to meet the requirement

(1)under 25 OC, τ is 1 hour, substitute it into (5) formula

45=80τ/ln2[1-e(- ln2/τ)·t]

Calculation 1-e(- ln2/τ)·t=0.39

e(- ln2/τ)·t=0.61

Both sides take logarithm with e as fundus t·ln2=0.495

t=0.71hour

Note: time for reaching 15ppm ozone concentration is not enough, it shall plus time for holding ozone concentration for 0.5hour, thus time for turning on ozone generator shall be T=0.71+0.5=1.21 hours.

(2)If temperature is higher than 35OC, thus τ=0.5h

45=[80/（2ln2）]·[1-e(- 2ln2)·t]

1-e(- 2ln2)·t=0.7796

e- 2 t·ln2=0.220

Take logarithm: 2t·ln2=1.5

t=1.5/(2·ln2)

t=1.5/1.386

t=1.08小时

T=1.08 hours

(3) T=1.08+0.5=1.58 hours

Eight. Why the effect of disinfection and sterilization with ozone in water is very good

There will come out following two kinds of reaction when ozone dissolves into water: One is direct oxidation; the other is it decomposes by itself to be hydroxyl free radical (-OH) under the induction of high-density hydroxyl of hydroxyl in water, hydogen peroxide, organic substance and humus, indirectly oxidizing organic substance and animalcule.

nine.Hydroxyl free radical is the most powerful oxidant, which capacity of disinfection and sterilization is stronger than ozone.

Due to double action of O3 and –OH, the effect of disinfection and sterilization with ozone in water is very good.

ten.Its advantages is: convenient operation, can easily change running parameter without affecting feeding effect and stability of working, little power consumption, structure of bubbling tower is simple and convenient for maintenance.

But its cubage is over large, pool-type covers large floor space, while tower-type requires higher workshop with higher with higher cost.

Blending process: use turbine pump can get good blending effect. Its cubage is small and technological parameter is easy to operate, but its structure is complicated with high cost, and large power consumption, complicated maintenance, also water storage tank is required to be equipped at the back of pipeline.

Eleven. Principle and method of test ozone generating output with iodimetry

Generally it uses iodimetry to test output of ozone generator per hour, which method is as following:

1．Dissolve K120g analytical reagent to purified water, to make 1000ml solution.

2. Dissolve 25g Na2S2O3·5H2O (hyposulphite) into purified water to make 0.1mol1000ml solution, thus among it, Na2S2O3 covers 158*25/（158+18*5）=15.93g.

3. Pour some quantitative KI solution into one container, infuse a little dilute sulfuric acid (so that solution comes to be acidity, to avoid ozone decompose over quickly), feed ozone into solution through gas distribution head for 30s, thus the solution appears brown (color is darker with more ozone). The process is Equation ①

4. Drop some hyposulphite onto the above obtained solution until it becomes colorless, which process is Equation ②. Cubage of consumed hyposulphite solution (ml) multiples 0.288 (see computation formula ) ③ of generating output from ozone generator (g).

Test principle of iodimetry is based on following equation:

O3+2KI+H20＝O2+I2+2KOH ①

I2+2Na2S2O3＝2NaI+Na2S4O6 ②

Suppose ozone generating output in 30s is Ag, consumed Na2S2O3 solution is Bml, thus Na2S2O3 covers 15.93B/1000g.

Predigest equation to be O3 ∽2Na2S2O3 .

48 316

A 15.93B/1000

Thus A=48*15.93B/1000/316(30s),

Calculate to get ozone generating output in 1 hour is 120A=120*48*15.93B/1000/316=0.288B ③

Twelve. How to quickly test residual ozone concentration in water

Use Model CHYC-1 tester of ozone concentration in water (Pls. refer to product introduction of our company )

Test Method: Add 5ml tested ozone water into A and B cuvette respectively, add a small bag of DPD testing powder into B cuvette at the same time, water turns red at once, turn CD to compare colors of two windows, while they are at the same color, the ozone concentration in water is the data get from the reading window. （Note:This method is not suitable to tested water which is alkalescent, but sterilization effect still exists.）

Thirteen. How to test residual ozone concentration in air

Use Model CYQC-1 tester of ozone concentration in air (Pls. refer to products introduction of our company)

Testing Method: break off two ends of testing tube, and insert it into air sampler as per the direction on the figure. Draw out 100ml of tested air including ozone with the sampler, enabling the blue cotton soaked with chemical medicine in the testing tube, which is for oxygenize ozone, being changed to be white, and the ozone concentration in air can decided from reading scale of testing tube by the whiten length.