Encyclopedia of Environmental Science and Engineering, Volume I and II

104 AIR POLLUTION SOURCES

Part 1. Pollutant Emissions (continued)

Pollutant types Sources and abundance Abatement and control

of the elements essential to the human body, a high

atmospheric concentration may result in poisoning

and disease of several types.

air pollution. The organic compounds that have

been tested as additives in gasoline, fuel oil, and

diesel oil for use in both internal combustion

engines and turbine engines may become an

increasingly important source of pollution.

Natural occurrence: Manganese is widely

distributed in the combined state, ranking

12th in abundance (100 mg/m^3 ) among the

elements in the earth’s crust.

Almost all of the manganese in the atmosphere

enters as manganese oxides, such as MnO,

Mn 3 O 3 or Mn 3 O 4.

precipitators, high-efficiency

scrubbers, and fabric filters.

k. ZINC: A bluish-white metallic element occurring

combined as the sulfide, oxide, carbonate, silicate etc.

resembling magnesium in its chemical reactions.

Although zinc is an essential element of the human and

animal body, zinc and its compounds have been found

to be toxic under certain conditions.

Natural occurrence: Zinc, widely distributed in

the earth’s crust, occurs in small quantities in

almost all igneous rocks.

The primary sources of emissions of zinc

compounds into the atmosphere are zinc, lead,

and copper smelting operations, secondary

processing to recover scrap zinc, and possibly

the incineration of zinc-bearing materials.

Zinc oxide fumes are the zinc compounds

most commonly emitted from these sources.

Zinc gores—can be collected by

electrostatic (rod-curtain-type)

precipitates and then further treated

in cyclone scrubbers.

Zinc particles—can be collected by

use of electrostatic precipitators,

a central cloth-bag collector system,

or soil efficient filtering device.

l. BARIUM: A silvery white malleable, active,

divalent, metallic element occurring in combination

chiefly as barite. Inhalation of barium compounds

can cause Baritosis a non-malignant lung disease.

Characterized by fibrous hardening.

Major sources are: (1) Industrial process

involved in mining, refining and production of

barium and barium-based chemicals.

2) Use of barium compounds as a fuel additive

for the reduction of black smoke emissions

from diesel engines. (This is accomplished by

the production in vehicle exhaust of micron-

sized particles which have minimal effects on

visibility.) Concentration of about 0.075 per

cent barium by weight of additive is most

effectively used.

Natural abundance: Barium frequently appears

as gangne in lead and zinc ore deposits. The

two main minerals are barite (barium sulfate,

BaSO 4 ) and witherite (barium carbonate,

BaCO 3 ).

The conventional methods for removal

of barium are the same as those for

solids, and include bag filters,

electrostatic precipitators, and wet

scrubbers.

Part 2. Major Air Pollution Sources

Chemicals manufacturing industry Nature of activity Type of air pollution problems

ADIPIC ACID Adipic Acid, COOH  (CH 2 ) 4  COOH, is a

dibasic acid used in the manufacture of

synthetic fibers. Adipic acid is produced by

the oxidation of cyclohexane by air over a

catalyst and then purified by crystallization.

Emissions: The only significant emissions from the

manufacture of adipic acid are nitrogen oxides. In

oxidizing the cyclohexanol, nitric acid is reduced to

nonrecoverable N 2 O and potentially recoverable NO

and NO 2 emitted into the atmosphere.

AMMONIA The manufacture of ammonia (NH 3 ) is

accomplished primarily by the catalytic

reaction of hydrogen and nitrogen at high

temperatures and pressures.

Emissions: Range from CO, HC, to NH 3 gases. Wet

scrubbers and water can be utilized to reduce the

atmospheric emissions.

CARBON BLACK Carbon black is produced by reacting a

hydrocarbon fuel such as oil and/or gas

with a limited supply of air at temperatures

of 2500–3000°F. Part of the fuel is burned

to CO 2 , CO and water, thus generating heat

for combustion of fresh feed. The unburnt

carbon is collected as a black fluffy particle.

Emissions: A high percentage of the emissions are carbon

monoxide and hydrocarbons. The particulate and

hydrogen sulfide problem are not as prevalent but do

occur at amounts warranting attention. NO 2 emissions

are relatively low due to the lack of available oxygen in

the reaction.

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