[PDF] Unit 14 - Industrial Chemistry and Environmental Pollution

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1 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

1.Industrial Chemistry and Enviornmental Pollution

Content

1.1

Industrial chemisty

1.1.1

Chemical industry

1.1.2

Requirements to be considered in

establishing chemical industries 1.1.3

Use of raw materials for chemical

industry

1.2 Extraction of magnesium - (DOW

process) 1.3

Caustic soda (NaOH) production

1.4

Production of soap

1.5 Production of sodium carbonate (Solvay process/ ammonia soda

method) 1.6

Production of ammonia

(Haber Bosch method) 1.7

Production of nitric acid

(Ostwald method) 1.8

Production of sulphuric acid

(Contact process) 1.9

Production of titanium dioxide

from rutile

1.10 Extraction of iron1.11 Polymers

1.11.1

Rubber and plastic

1.11.2

Natural rubber

1.11.3

Vulcanizing natural rubber

1.11.4

Addition substances used for the products related to polymer 1.12 Chemical products related to plant resources

1.12.1

Production of vinegar

1.12.2

Production of ethanol

1.12.3

Essential oils

1.12.4

Bio diesel

1.13 Chemistry of air pollution caused by industrial emissions

1.13.1

Acid rain

1.13.2

Global warming

1.13.3

Depletion of the ozone layer

1.13.4

Photochemical smog

1.14 Chemistry of water pollution caused by industrial discharges

1.14.1

Water cycle and water pollution

1.14.2

Water quality parameters

1.14.3

Waste water quality parameters

2 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution 1.1

Industrial Chemistry

1.1.1

Chemical industries

Colossal changes occurred in the mode of production and the force of production during the and social problems tended to emerge. Hence more attention had to be paid to reduce productivity. Alongside the gaming of a special place by chemical industries in the sea water is one of the chemical industries in our country. are some of the chemical industries carried out in our country at prese nt. Chemical industries spread out and establish in global scale area diverse. They can be knowledge on such is an entrance to 'Industrial Chemistry' discussed her e. 1.1.2 Requirements to be considered in establishing chemical industries There are requirements that should be considered when establishing a chemical industry.

Some of them are given below.

Capital

Supply of raw materials

Labour

Technology

3 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

Assurance of the production process

Assurance of continuity

Waste products and methods of waste management.

Strategies for preventing the addition of environmental pollutants by th e industry.

Site of installation

Transport facilities and market

Nature of probable accidents and strategies that can be adopted to preve nt accidents Safety of the production process and prevention of accidents are very important in chemical industry. For this some of the disasters occurred in relation to chemical of one week. The reason for this was found to be the leakage of the highly poisonous gas 1.1.3

Use of raw materials of chemical industry

Raw materials are the substances that are supplied from outside for a chemical industry and which take part in the production process. Production of compounds such as NaHCO 3 2 SO 4 cha this. Atmospheric air is the source from which this nitrogen is obtained. Atmospheric air is 2 gas is separated by fractional distillation and used for ammonia air is directly used to obtain NO 2 2 4 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution in which form the raw materials should be used. consideration.

Occuring in large deposits for long term usage

Easy to reach

Purity

Hydrogen gas obtained by cracking of hydrocarbons is used as an essential raw material production of iron. A brief account on the raw materials used for some products is given belo w. Air nitric acid and sulphuric acid. Atmospheric air is used as a raw material in these productions. liquefaction of air followed by fractional distillation is used as a raw material in atmospheric air is used as a raw material. Air

Fractional

distillation N 2 gas H 2 gas NH 3 NO 2 gasWater HNO 3 air Water 5 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution reason for this is that various salts presents in sea water interfere with the production process and also get into the product as impurities. Hence it is very important to take care about the standards of the raw materials. NaCl NaCl is obtained using sea water as a raw material or from the ores of rock salt. Caustic soda is produced using NaCl as a raw material. It is also used as raw material in the But sea water cannot be used as a raw material for the production of cau stic soda.

Minerals

materials. Also minerals containing phosphates are used for the production of phosphate Coal is a major reducing agent.

Crude oil

and diesel. Crude oil is the main source from which raw materials for the production problem with its consumption. Another crisis is the increase in global warming caused by

Plants

resins and medicine. Plant materials are known as biomass and used as fuel for industries and also as raw materials for the production of various orgnic compounds. As Plants is cycles in the environment. Industries which used petroleum oil to generate power have started to use biomass as an alternative source of energy. Industries in our country too are inclined towards this. 6 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

1.2 Extraction of Mg - Dow process

Raw materials essential for extracting Mg by Dow process.

Other than Na

2+ by weight is magnesium. The solution discarded at the last stage of producing salt from

Step 1

decomposition of limestone. Dolomite also can be used for this purpose. CaCO 3 2 CaCO 3 3 2 carbonate is a disadvantage.

Step 2

2 2+ ions. 2 dissolves slightly in water giving Ca 2+ and OH 2 is 2 2+ 2 by OH 2 2 goes into solution releasing OH 2 2 2 with 2 is a disadvantage. 2 2 2 2+ + 2OH 2+ 2 7 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

Step 3

2 2 2 2 2 2+ ions in the solution 2 precipitaed.

Step 4

The solution is heated strongly to vaporize water. Then it is dried so that the amount of 2 2 2 .4H 2 2 2 .4H 2 2 .2H 2 2 First the solid formed is fused in the steel chambers where electrolysis is done and then it is

C. Since

2 the temperature of the fused salt should be maintained above those melting temperatures. 2 2 2Cl Cl 2 Cl 2 2 to produce 2 2+ C. 8 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

Steel containerMolten Mg globules

Mg globules travel

through the holes of cathode Fused MgCl 2 Cl 2 gasGraphite anode

Tubes that supplies fuel gases for the burner

Figure 1.1

The cross sectional structure of the electro chemical cell producing magnesium is very important for the production of alloys to have this kind of prop erties. 2 to the atmosphere is a disadvantage. CO 2 is added to the atmosphere during the burning of limestone or dolomite and combustion of petroleum fuels to obtain a higher temperature associated with the electrolysing c ell. 1.3

Production of caustic soda (NaOH)

A pure concentrated solution of sodium chloride is called brine. NaOH is produced by released at the cathode and the anode respectively. 2 2 2 2 electrolysis equal. In spite of the amounts of moles of chlorine and hydrogen formed are equal the amount of chlorine gas that can be collected in gaseous form is somewhat less than the amount of hydrogen. 9 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution

There are three types of cells.

possibility of releasing mercury to the environment and contamination of NaOH with minute quantities of mercury are its main disadvantages. The basis of membrane cell and ions is used to separate the of Na ions from the anode chamber to the cathode chamber. It also prevents the movement of OH ions from the cathodic solution to the anode chamber solution. But consumption of electricity and minimal impact on the environment are the advantages of the employment of membrane cells. factors. This information is given in the following table.

Table 1.1

The factors included in associated with the cells are used for caustic s oda production

Mercury cell

Diaphragm cell Membrane cell

Membrane cell method

The brine that is used in the membrane cell method should be very pure. Presence of 2+ 2+ and SO 4 ions in brine hinders the production process. Precipitations of these cations when the solution becomes basic disturbs the cell action. Loweri ng of the purity of 10 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution 2+ 2+ and SO 4 in brine prepared by this salt is a very important step. Sulfate ions can be precipitated and removed as BaSO 4 2+ and Ca 2+ ions 2 and CaCO 3 by adding NaOH and Na 2 CO 3 adequately. 2+ Ca 2+ 32-
CaCO 3 Ba 2+ 42-
BaSO 4

Chlorine

Ttitanium anode

Selective

MembraneUsed salt solution (out)Inserting the concentrated salt solution (brine solution)Hydrogen

Inserting water

NaOH solution (out)

Nickel cathode

Figure 1.2

At the beginning the solution in the anode chamber mainly contains Na and Cl ions and very small amounts of H and OH ions formed by the dissociation of water. The ions at the anode to give O 2 ions at the anode to liberate Cl 2 2 in addition to Cl 2 . Several 4OH O 2 2 2Cl Cl 2 NaCl concentration in the brine used to produce caustic soda is relatively high. In a situation where the OH concentration is very low and the Cl OH ions on the electrode is relatively low. Since there is a relatively higher concentration 11 G. C. E. (A/L) CHEMISTRY - UNIT 14Industrial Chemistry and Enviornmental Pollution of Cl 2 of Cl ions is relatively greater.

With the electrolysis when the Cl

ions liberating O 2 is continuously pumped into the anodic chamber and anodic chamber solution is continuously removed. Though the Cl ions are given 2 anodic chamber solution or Na ions should migrate into the cathodic chamber solution.

Reduction takes place in the cathodic chamber. H

ion is more easily reduced than the aqueous Na ion. At the beginning the medium in the cathodic chamber has no sodium ions resulted by the dissociation of dissociation of water molecules drops. Since water molecules continuously dissociate with the removal of H ions formed by the dissociation of water as H 2 ion concentration in the cathodic chamber increases. When electrolysis is carried out ion concentration in the cathodic chamber rises with time. The equilibrium brought about by the dissociation of water molecules can be shown by H 2 The situation where the equilibrium is lost due to reduction of H ions to H 2 molecules is H 2 H

In the cathodic chamber H

ions get reduced to H 2 molecules at a rate equal to the rate of ions to Cl 2 ions is equal to the rate of decreasing of Cl system is electrically neutral. ions inquotesdbs_dbs17.pdfusesText_23

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