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CAUSTIC SODATransforming saltinto various productsfor our daily lives.
CA
US
TIC
SO
DA
An importantchlorineco-product
The transformation of salt and water into caustic soda and chlorine
The chlor-alkali production chain begins with electrolysis, by passing an electrical current through a solution containing sodium chloride (salt) and water, using one of the three most common processes in its industrial manufacturing: mercury cells, diaphragm cells or membrane cells. Electrolysis is the process whereby salt and water molecules are broken and subsequently regrouped into caustic soda, chlorine and hydrogen molecules. The production results in a fixed ratio of 1.12 tons of caustic soda per ton of chlorine. Hydrogen, which is also a by-product of the electrolysis, is recovered and then used as fuel or raw material for the production of hydrochloric acid. Other products in this industry are sodium carbonate (soda ash), potassium hydroxide (caustic potash), hydrochloric acid and sodium hypochlorite.
Caustic soda is an essential reagent for the production of various organic chemical products. Among the main applications is the bleaching of pulp and paper, besides being widely used in the chemical and petrochemical industry, metallurgy (alumina production for the aluminum industry), soaps and detergents, textile and food industries. Of natural origin, it plays an important role in pollution prevention and treatment of wastewater, enabling many industrial processes (for further details see the products derived from caustic soda inside this booklet).
In 2015, the worldwide production capacity of caustic soda stands at around 92 million metric tons.
Caustic soda is highly valued for its neutralizing power and also because it helps to control and remedy acidic pollution of the environment. Therefore, it is used in various processes to control acidity, neutralize acid wastes and washing gases. As it is an alkali compound, caustic soda is a chemical opposite to acids and can therefore neutralize them. The neutralization reaction produces water and salt. Gas washers are devices used for air pollution control designed to use the alkaline properties of caustic soda. Such systems neutralize the acid gas emissions from chimneys, thereby helping to make the environment cleaner and pollution free. Moreover, metal plating facilities generate waste containing dissolved heavy metal concentrations that must be removed before the effluents are discharged into municipal sewers and surrounding water bodies. Normally this can be achieved by adding an alkaline chemical product like caustic soda to the effluents. The insoluble metal hydroxides formed by the reaction between caustic soda and metals of effluents are physically removed as part of the pre-treatment of effluents.
Caustic soda can also be used to neutralize acid drainage from mines. During mining opera-tions, when air and water come into contact with freshly extracted minerals containing sulfur, these rapidly oxidize and release a certain amount of acidity, metals and other chemical components that are harmful to the environment. Acid mine drainage is a major environmen-tal hazard. Caustic soda is particularly effective in neutralizing low flows of acid drainage from mines in remote locations, as well as treating flows that have a high manganese content.
Caustic soda plays an important role in the manufacture of soap powders, soap bars and detergents, in addition to being used in the production of industrial soaps and special soaps. Developing countries have a significant demand for caustic soda, because in some of these countries, bar soap is used exclusively for washing fabrics and for personal hygiene. The special soaps include soaps for cleaning ovens and equipment for food preparation, more potent detergents for dishwashers, floor cleaning, metal cleaning, paint removers, liquid soaps and shampoos.
Caustic soda is used in the production of cotton fabrics to strengthen the fibers and better absorb the dye. Estimates indicate that around 90% of the cotton is treated with caustic soda. Caustic soda also has a number of other applications in the food industry, for example, in refining animal and vegetable oil, to remove fatty acids and to peel vegetables and fruit, as well as in the pharmaceutical industry where sodium phenolate is used in antiseptics and to produce aspirin (acetylsalicylic acid). Large quantities of caustic soda are also demanded by the pulp industry to manufacture paper and in the alumina manufacturing process to produce primary aluminum. Additionally, significant amounts of caustic are used in treating municipal and industrial waste water.
Helping tocontrol pollution
Help in personal hygiene
Various andnumerous applications
Caustic Soda Applications
Caustic soda is the main by-productin chlorine production.
5% 12%
14%
14%
15%
17%
23%
Water treatment
Inorganic chem. Prods.
Aluminum industry
Paper & Pulp
Soaps, detergents and textiles
Organic chem. Prods
Other
#HereThereIsCausticSoda
CatalystsDyes
Synthetic detergents
Food
addit
iveSu
rfacta
nt ag
ent
Hum
idifyi
ng ag
ent f
or fa
brics
Disinf
ectan
tsDr
yers
Emuls
ifiers
Fuel
addit
ives t
o red
uce p
olluti
on
Surfa
ctant
agen
tEm
ulsifie
rsOre
flotat
ionSo
aps
Waterpr
oof fa
brics
Fabric
s man
ufactu
ring
Cotto
n merc
erizat
ion
Cotto
n clea
ning
Fabric
s dye
ingAdh
esives
Electro
nic co
mponen
ts
Coatin
gs
Essences (a
romas)
Perfumes
Sodium
chloroacetate
Sodium cyanide
Sodiumformiate
Sodium chlorite Bleaching of fabrics, paper pulp, edible oils, straw productsOxidizing agents for dyes
Sodium-carboxymethylcellulose
Dyes
Vitamins
2.4 Dichlorophenoxy acid - aceticCrop protection chemicals
AdiponitrileHexamethylenediamine
Nylon 66
Nylon 610
Expansion agents
buoyancy agents in sea rescues
Fuel cell
Pharmaceuticals
Metal prints on glass
Polymerization catalyst
Rocket propellants
Elastic fibers for clothing
Food products (especially ice-cre
ams and diet foods)
as a drying agent, thicke
ner, suspending agent and emulsio
n stabilize
r /
Paper coating, printing, pharmaceutica
l and cosmetic products /
fabrics manufacture (dyes)
Artificial blood vessels / Synthetic grass (sy
nthetic floors) /
Car carpets / Tow / Electric w
ire insulators / fishing lines and nets /
Gears and bearings / Parachutes / Pen tips / Rugs and carpets/
Boat sails / Surgical sutures / Te
nnis racket strings
Toothbrush bristles, hairbrushes, brushes / S
ocks /
Tire strengthening materials / C
lothing (combination of wool
and cotton to increase durability and resistance)
Steel tempering process and thermal treatment agent
Ethylenediaminetetraacetic acid (EDTA)
Blood anticoagulant and to reduce cholesterol /
Liquid soaps / Shampoos
Ore flotation
DyesPharmaceuticals
Black nickel platingDyingPharmaceuticalsRubber treatments
Extraction agent in mining for theproduction of gold and silver
Electroplating agent for copper,zinc, brass and cadmium
Fabric degumm
er
Black dyes
Leather preparation
Blueprint copy paper / Ceramics and glasses
Fixer for dyes / Hydrogen peroxide stabilizer
Fireproof fabrics / Tin plating
Zinc d
imeth
yldith
iocarb
amate
Crop p
rote
ction
chem
icals
Rode
nt pe
sticid
es
Bleach
ing ag
ent fo
r soa
ps an
d mola
sses
Remov
er for
fabri
cs
Ceram
ics
Pigmen
ts for
fabrics
Button battery
(especia
lly for m
iniature e
quipment)
Cosmetic
s
Paint pigment
Perfumes
Pharmace
uticals
Polishing components
ABS resins
Car parts
Boats
Registering machines
Home appliances
Bags
Radiator grids
Shoe heals
Shower boxes
Phones
Toys
Nitrile rubbers
Glass manufacturing
Manufacture of additives for oils and greases
Beetroot sugar refining
Steel carbonization agent
Cadmium electroplating
Fertilizers
Paint pigments
Pharmaceuticals
Condiments, seasonings
Anti-mold agent for food
Antiseptic products
Aspirin (acetylsalicylic acid)
Intermediary dyes
Home appliances / Car panels
Cosmetics and packaging
Gardening equipment
Medical equipment / Toys
Electrical enclosures / Cutlery
Cata
lyst f
or vu
lcaniz
ing ru
bber
Fung
icide
CatalystsFixer for dyesAgent for leather tanning
ElectroplatingPharmaceuticals
Oxalic acidWallpaper printing
Automotive radiator cleaner, purifying
and intermediary agents for chemical
components, rare earths processing,
Fabrics bleaching, Leather tanning)
Cellulose xanthate
Alkaline cellulose
Wrapping for gifts and packages
Mixed with cotton household products
(curtains, bedspreads, tablecloths)Coated fabricsFelt articles and blanketsNon-woven fabricsClothing
Rayon
Cellophane
Ethylcellulose
AdhesivesVarnishes
(bowling pins, electrical equipment coating)Paints for stampingPharmaceuticalsCoating for pillsLacquers
Coating for foodPaints
Latex paintings
Pharmaceuticals
2-Hydroxypropyl cellulose
2-Hydroxypropyl methylcellulose
Hydroxyethyl celluloseAdhesivesAsphalt emulsions
CementCosmetics
Gelatins and pharmaceutical lotionsFabrics processing
Alum
inum
stea
rate
Calci
um st
earat
e
Zinc s
tear
ate
Cosm
etics
Gellin
g age
nts
Grea
ses
Phar
mac
eutic
alsSta
bilize
r for
plas
tics
Soap
Xylene sulphonic acid
Aluminum
HydroxideSodium
Polysulfide / Sodium Sulfite
Sodi
um st
eara
te
Sodi
um la
uryl
sulfa
teSo
dium
naph
then
ateSo
dium ol
eate
Epoxy
resin
Vanillin
Purification of gases
Fruit and vegetables peeler
Sodium chemistry
Graphic prints
Galvanization
Oil Refining
Others
Regeneration of ion exchange resins
Food additives
Wood pulp (process with soda)
Wall coating / Pulp bleaching
Sodium stannate
Hydrazine
Sodium Sulphite
Sodium Arsenite / Sodium
Bromite
Sodi
um d
imet
hyld
ithio
carb
amat
e
Sodi
um D
initr
o-o-
Cres
olat
e
Sodiu
m Form
aldeh
yde S
ulfox
ylate
Copp
er Hyd
roxide
/ Man
gane
se Hyd
roxide
Mercury OxideAcrylonitril
e
Nickel / Beryllium / Barium HydroxideCadmium / Cobalt / Lead Hydroxide
Sodium Molybdate
Monosodium Glutamate
Kraft paper refining (Cellulose)
Sodium Propionate
Sodium Phenolate
Sodium Metasilicate / Sodium Orthosilicate
Sodium Picramate
Polycarbonate
Sodiu
m Di
urana
te / T
ungs
tate /
Fluo
roacet
ate
Alkaline solutions to wash jars and bottles
Disinfectants / Wastewater treatment
Rubber stabilizers (Latex)
Metal ProcessingFlotation of ores, metal degreaser
pH controlVegetal oils refining / Extraction of gelatin
Rubber regeneration agent
Plastics
Sodium thiocyanate
Electroplating
Oil additives
Sulfur dyes
Synthetic rubber
Aluminum
polychloride (APC)
Aluminum
sulphate
Manufacture of coagulants for treating
water and effluents, catalysts, flexible
polyurethane foams and flam
e
retardant and smoke suppressor in
polymeric m
aterials
Production of glass, glass
fibers, refractory products,
refractory concrete, technical
ceramics, ceramic coatings,
aluminous electrical insulators,
abrasives, white electro-casted
alumina and polishing pastes
Cans, aluminum foil, food
packaging / Windows, doors,
partitions and grids/ Components
in boats, airplanes, cars, bicycles /
kitchen utensils and tools
Aluminum
Aluminum Oxide
(Alumina)
Sour
ce: W
orld
Chlo
rine C
ounc
il