capture of mercury vapor in air with potassium permanganate solution [PDF]

vapor in air. Mercury was captured with various types of impingers containing a solution of potassium permanganate (KMnO

3 downloads 3 Views 557KB Size

Recommend Stories


Potassium Permanganate
Life is not meant to be easy, my child; but take courage: it can be delightful. George Bernard Shaw

Oxydabilité au permanganate de potassium
Almost everything will work again if you unplug it for a few minutes, including you. Anne Lamott

How to use potassium permanganate soaks
You often feel tired, not because you've done too much, but because you've done too little of what sparks

Comparison of 5% potassium hydroxide with 10% potassium hydroxide solution in treatment of
You often feel tired, not because you've done too much, but because you've done too little of what sparks

Potassium Fluoride Solution
Nothing in nature is unbeautiful. Alfred, Lord Tennyson

mass transport of potassium permanganate matiux interactions by
Life isn't about getting and having, it's about giving and being. Kevin Kruse

air & vapor barrier
I tried to make sense of the Four Books, until love arrived, and it all became a single syllable. Yunus

AIR & VAPOR BARRIER
Suffering is a gift. In it is hidden mercy. Rumi

Soil Vapor and Air analysis
Almost everything will work again if you unplug it for a few minutes, including you. Anne Lamott

air & vapor barriers field guide
Keep your face always toward the sunshine - and shadows will fall behind you. Walt Whitman

Idea Transcript


Industrial

Health,

1975, 13, 243

CAPTURE

OF

MERCURY

VAPOR

IN AIR WITH

PERMANGANATE

SOLUTION

Noboru

National

Institute of Industrial

POTASSIUM

HARA

Health,

Kizuki-Sumiyoshi,

Nakahara-ku,

Kawasaki

(Received July 30, 1975)

The

vapor

author

tried

in air.

solution

a series

Mercury

of potassium

solutions.

Though

permanganate

all the types

This solution

pling solution changes educes out gradually. educed

manganese

in amount. and sulphuric dioxide.

Mercury

vapor

permanganate

and sulphuric

of

under

high

impingers efficiency,

mercury

vapor.

of capture

various

there The

were author

of mercury,

for the analysis

and mercury necessary

in air was

with

of mercury

and sampling excellent

a

solu-

sampling

permanganate

in liquid phase part

in the sam-

was rather

in capture

of mercury

impinger

containing

efficiency

was observed

unknown a series

all the types

factors

in

of the most

little

of mercury, on manganese

a mixture using

of potassium several

of impingers

the

of experiments

mechanisms

types

had a very of

capturing

for the study of the mechanism suitable

method

of air sampling

vapor.

EXPERIMENTS

Vapor

mercury

containing

acid (H2SO4) as sampling

mercury

adsorption

Though

and for the research

of mercury

the

Sampling

many

of capturing

of impingers

potassium

captured

for

conditions.

tried

between

played a great

captured

acid.

purpose

types

dioxide, and granules of manganese dioxide part of captured mercury was adsorbed on

permanganate

was

the

used had a very

dissolved

to manganese The greater

dioxide,

acid

of reaction of impingers

is unstable:

Potassium

for

with various

(KMnO4) in sulphuric

the mechanism

tion is complicate, efficiency.

of experiments

was captured

AND RESULTS

used in all the experiments

was produced

by a reduction

reaction

between mercuric chloride (HgCl2) and stannous chloride (SnCl2.2H2O) in dil. H2SO4.

Sampling

procedure1.2)

Sampling

was proceeded

using

four types

of

impingers

with

their

transformations

(Fig. 1). Two

impingers

and worked

and two bottles

as buffering

zones during

were

arranged

sampling 243

as in Fig. 2. procedures.

Two bottles were empty

Two

impingers

were

the

N. HARA

Fig.

1.

Types

of used

impingers

1 normal impinger

Fig.

same

each

each

sampling

conditions.

other

2.

and

normal impinger (with filter)

3

Muenke : washing

4

midget impinger

Arrangement tank

B

impinger

C

bottle

D

impinger

E

bottle

F

flow meter

equal

of vapor

zone

of sampling

vapor

captured

procedure.

zone

for buffer

volume

for sampling

of mercury

for buffer

Mercury

of mercury

bottle for gaseous material

of instruments

A

an

procedure. Amounts

2

was

passed

in the first 244

solution

and

was poured

through the

them second

into them under

impingers

the

on set were

CAPTURE shown

as

calculated

a, as

b

(ƒÊg)

OF

respectively,

MERCURY

and

then

VAPOR sampling

IN

AIR

efficiency

of

the

impinger

r

was

follows.

a-b r= a

Sampling procedures were made under the following conditions and all the types of impingers had a very excellent sampling efficiency for mercury vapor. Concentration Sampling

Table

1.

Normal

(a)

of mercury

solution

1.

vapor

in air

:

0.5% KMnO4=1 N H2SO4

Sampling

efficiencies

sampling

solution:

sampling

time

of impingers 0.5%

depth of sampling solution (3 cm)

Normal impinger

KMnO4=1

: 10 mins

impinger

(b) depth of sampling solution (2 cm)

2.

(Table 1)

10•`1000 ƒÊg/m3

(with filter)

(a)

depth of sampling solution (3 cm)

(b)

depth of sampling solution (2 cm)

245

for vapor N H2SO4

of mercury.

N. 3.

HARA

Muenke

Volume of sampling solution (about 60 ml) (the surface of the sampling solution reached the most constricted of inner tube)

4.

Midget

point

impinger

Volume of sampling solution (5 ml)

Figures

Determination

show

the percentage

of sampling

efficiencies.

of mercury

Reducting solution* was dropped

into sampled

solution slowly until the

solution

became colorless, and one more droplet was poured. (MnO2=H2SO4 solution which contained no KMnO4 in it was also used as sampling solution. In such cases, reducting solution was dropped until granules

of MnO2 were dissolved thoroughly.)

Then the

sampled solutions were removed to volumetric flasks and water was added to the mark. The

aliquot volume of the solutions was used for determination

determination, As very

the

analytical

high,

volume impinger

only

of

of

therefore, the

were vapor

sensitivity

0.1 ƒÊg

air, was

experiments mercury

an atomic absorption spectrophotometer

most

will

be

in

for

the

of sampling

Velocity

of passing

spectrophotometer

for

its

for

conditions.

solution

5•`20

For the

ml

the

mercury

(in

All

cases

each

mercury

A

purpose.

In

following

air

of

this

impingers.

for

determination.

determination

sufficient

midget

Volume

absorption

sufficient

enough and

with

sampled

atomic was

convenient

performed was

of

mercury

of mercury.

was used.

of

very

was small

in

it.

A

of

the

following

midget

midget

impingers,

impinger)

0.5∼2.5 l/min

DISCUSSION

Mercury *Reducting

(NaCl)

vapor

solution:

dissolves 20 g of

were dissolved

in conc.

hydroxylamine

H2SO4 hydrochloride

in 100 ml of water. 246

and

it does (NH2OH•EHCl)

not

dissolve and

12 g

in dil. of

sodium

H2SO4. chloride

CAPTURE

Mercuric

sulfate

OF

MERCURY

VAPOR

IN

AIR

(HgSO4) dissolves in dil. H2SO4. It was, therefore, guessed that Hg°

(vapor of mercury) was oxided to Hg+2 by KMnO4 at the first step, and Hg+2 dissolved in the sampling solution at the second step. Capturing of mercury vapor, however, may not wholly be proceeded by such simple chemical mechanisms. Change

of composition

of potassium

permanganate

in

diluted

sulphuric

acid

(KMnO4=H2SO4) The sampling

solution

to MnO2 gradually.

in this experiment

KMnO4 dissolved

in it changes

MnO2 educes out from the solution, and the concentration

in the solution decreases slowly. concentration

is unstable:

of KMnO4

The speed of decrease was especially effected by the

of H2SO4 in the solution.

In addition, it was

centration of KMnO4 even if in same concentration

also effected by the

of H2SO4. (Fig. 3) The speed was

very diverse according to individual conditions, and Fig. 3 shows the average various experimental

results.

con-

values of

(The solutions were put in the room keeping away from

direct sunshine.)

Fig.

3.

Decrease

of con.

concentration Letters

of KMnO4

in

KMnO4=H2SO4

the

beginning

solution.

of H2SO4 1N

on the curves

show

concentration

of KMnO4.

Sorption of mercury As the composition mechanism

for mercury

in liquid phase and on granules of KMnO4=H2SO4 vapor

changes

solution

naturally. 247

of manganese

changes Mercury

every

dioxide

moment,

was captured

(MnO2)

the sampling into the liquid

N.

HARA

phase and it was also adsorbed on educed MnO2. If very fresh sampling solution is used, the greater part of mercury will be captured into the liquid phase. (At this time, the

amount

elapsed

of educed MnO2 is very

small.)

Using KMnO4=H2SO4 solution which

one day after its preparation, however, the majority of mercury is adsorbed on

granules of MnO2. KMnO4=H2SO4 solution containing no MnO2 can hardly be prepared. In addition, MnO2 was produced little by little owing to reduction of KMnO4 during the sampling procedure. amount

The ratio of capacity of sorption

in liquid phase and adsorbed

elapsed after the preparation

Fig.

4.

Aging

of sampling

passing

The

in

of

the

sampling

was

investigated

0.1%, was If

KMnO4

the less

experiments

in

1 N

(Fig. efficiency 0.1%,

very

diluted

solution

KMnO4

during

sampling

be

oxided

showed

H2SO4

for

sorption

were

for 5). was the

the always

efficiency of

KMnO4 procedure.

into

between

dissolved

used

: 1% KMnO4=1N

volume

: 15 ml

Hg

: about

velocity

: 2l/min

time

: 10 mins

the

50 ƒÊg/m3

as

vapor

mercury which

sampling

solutions,

the

about

100%.

declined

as

(0.001•`0.002%) was solution.

248

KMnO4 But

the

in the

had

is

used,

be

oxided

various

and

the

relation

KMnO4

in

the

solution

was

concentration of the that

of

between

the

solutions more

mercury

lost

than

KMnO4

KMnO4

solution

for

concentra-

of

concentration

demonstrated

to

contained

concentration of

it

of

solutions

concentration

sampling

H2SO4

(KMnO4)

and

So

of Hg.

composition

The

mercury

If

and sorption

that

solution.

efficiency

than

solution

air

KMnO4=H2SO4

tion

solution

of potassium permanganate

following

sorption

for mercury

on granules of MnO2 changed as time

of sampling solution are shown in Fig. 4.

sampling

Concentration

amount

in

it

decreased. its

color

of

vapor

had

to

CAPTURE

Fig.

5.

OF

Sampling con.

MERCURY

efficiency

passing

IN

AIR

of solution.

of H2SO4

sampling

VAPOR

1N

solution air

volume

: 10 ml

Hg

: about

50 ƒÊg/m3

velocity : 1.5 l/min time

Concentration

of H2SO4

The effect of H2SO4 in sampling investigated. centration

: 10 mins

Concentration

solution on the sampling

efficiency was also

of KMnO4 in sampling solution was kept at 0.5% and con-

of H2SO4 in it was fluctuated.

Sampling procedure for mercury vapor was

proceeded with these solutions. Results of the experiments showed that the sampling efficiency was always 100%, and was not affected at all by fluctuation of concentration of H2SO4 (Fig. 6).

Even KMnO4 aq. (containing no H2SO4) had an efficiency of 100%

for capturing mercury vapor.

Fig.

6.

(It may be that mercury was oxided to Hg+2 by KMnO4

Sampling con.

efficiency

of solution.

of KMnO4

sampling passing

0.5%

solution air

volume

: 10 ml

Hg

: about

50 ƒÊg/m3

velocity : 1.5 l/min time 249

: 10 mins

N.

and Hg+2 dissolved into HMnO4.)

HARA

So it may be guessed that mercury must be oxided

first of all, and part of H2SO4 is not so great in sorption of mercury. Affection of manganese

dioxide (MnO2)

Solubility of MnO2 in H2O is very small. but its solubility

MnO2 dissolves scarcely

in dil. H2SO4,

in conc. H2SO4 is not so small (Fig. 7). From the results of the

experiments, it became clear that saturated solution of MnO2 in H2SO4 had no power of sorption for mercury vapor in it, regardless of the concentration saturated solution of MnO2 in H2SO4 suspended with granules ability

of sorption

for mercury

Fig.

Fig.

8.

vapor if the concentration

7.

Solubility

Sampling

sampling, passing,

of

saturated

MnO2=H2SO4

solution. solution

air

volume

: 15 ml

Hg

: about

50 ƒÊg/m3

velocity : 1.5 l/min time 250

But

of H2SO4 is large (Fig. 8).

of MnO2 in H2SC

efficiency

suspending

of H2SO4 used.

of MnO2 had a large

: 20 mins

CAPTURE

OF MERCURY

VAPOR

Sampling efficiency decreased in very concentrated of captured

mercury

concentrated

H25O4. In such cases, the amounts

in the first impinger decreased, by that in the second one did not

decrease so rapidly as concentration ing MnO2, amount

IN AIR

of H2SO4 increased.

of captured

In concentrated

H2SO4 was used, the larger became the percentages

in liquid phase

(Table 2). Table

2.

H2SO4 suspend-

mercury in liquid phase was not so small.

The more

of dissolved mercury

These phenomena showed that granules of MnO2 adsorbed

Distribution

mercury only if H2SO4 existed.

of captured

Hg in midget

impingers.

These might be due to the reduction

of MnO2.3) In

con. H2SO4, Mn+4 was not reduced to Mn2+. MnO2 dissolve in con. H2SO4 and Hg0 is oxided to Hg+2. Hg+2 was adsorbed liquid phase.

on remained

granules

of MnO2 or dissolves in

But MnO2 is not reduced to Mn+2 in dil. H2SO4, and Hg° is not oxided

to Hg+2. Mercury neither is adsorbed nor dissolves.

In other words, captured

mercury

was Hg+2 and not Hg0 (vapor of mercury).

REFERENCES

1) Sandell, E. B. (1959). science

2) Yasuda,

Publichers,

Tokyo.

Determination

of Trace Metals,

3rd ed. p. 635.

Inter-

New York.

K. and Hasegawa,

scopy), p. 344. 3) Chitani,

Colorimetric

Kodansha,

N. (1972).

Genshi Kyuko

Bunseki

(Atomic

Absorption

Spectro-

Co., Tokyo. (in Japanese)

T. (1956). Muki Kagaku

(Inorganic Chemistry),

(in Japanese)

251

4th ed., p. 962. Sangyo Tosho Co.,

Smile Life

When life gives you a hundred reasons to cry, show life that you have a thousand reasons to smile

Get in touch

© Copyright 2015 - 2024 PDFFOX.COM - All rights reserved.