Sulfuric Acid Uses & Applications

Sulfuric acid referred as universal chemical, king of chemicals due to the numerous applications for sulfuric acid as a raw material or processing agent. Sulfuric acid is the most commonly used chemical in the world and used in almost all industries like

• Fertilizers
• Pharmaceuticals
• Gasoline
• Automobile batteries
• Paper bleaching
• Sugar bleaching
• Water treatment
• Sulfonation agents
• Cellulose fibers
• Steel manufacturing
• Coloring agents
• Amino acid intermediates
• Regeneration of ion exchange resins

Sulphuric acid is an important industrial chemical which is used in the manufacturing processes of many goods over a wide range of applications. Sulfuric acid used in pulp and paper industry for chlorine dioxide generation, tall oil splitting and pH-adjustments. Over one million tons of sulphuric acid is made each year in the UK alone, with an additional 40 million tones being produced in the USA. Annual worldwide production of sulphuric acid is stands at around 180 million tones.

Sulfuric acid is a strongly acidic, oily liquid that may be clear to cloudy in appearance. Concentrated sulfuric acid acts as both an oxidizing and dehydrating agent. Sulfuric acid is available in many grades ranging from electrolyte grade (33 weight percent) for batteries, to 93 weight percent (66 deg Baume), 98 weight percent, and 20-22 weight percent fuming oleum containing excess dissolved sulfur trioxide. The grade most often shipped is 93 weight percent.

In the environment, sulfuric acid is a constituent of acid rain, since it is formed by atmospheric oxidation of sulfur dioxide in the presence of water. Atmospheric sulfur dioxide is generated by combustion of sulfur-containing fossil fuels such as coal and oil.

Sulfuric acid was once known as oil of vitriol, coined by the 8 th century Arabian alchemist Jabir ibn Hayyan.It was prepared by Johann Van Helmont in the 1600s by destructive distillation of green vitriol (ferrous sulfate) and by burning sulfur. Burning sulfur with saltpeter (potassium nitrate) was first used to prepare sulfuric acid in the 17th century.

By the mid-17th century, John Roebuck had invented the lead chamber process which used nitrogen oxides as oxidant. The contact process, wherein the oxidation of sulfur dioxide to sulfur trioxide is performed by oxygen (air) over a catalyst, was originally developed about 1830 by Peregrine Phillips in England.

In discretionary production, the mining of sulfur or sulfur-bearing minerals (pyrites) is the sole objective, based on the voluntary mining of discrete deposits to obtain maximum economic recovery. In non-discretionary production, sulfur or sulfuric acid is recovered as an involuntary by-product, the quantity of which is subject to demand for the primary product alone.

The lead chamber process has now been almost completely superseded by the contact process in the industrial production of sulfuric acid. Much of the sulfuric acid produced by the lead chamber process is utilized in the making of fertilizers, since the acid is relatively dilute. In contrast, the contact process can make acid of any desired concentration.

Sulfuric acid is a very important commodity chemical, and indeed, a nation's sulfuric acid production has been a reasonably good indicator of its industrial strength for the last century or so.

Here are some of the growing number of end-uses and applications using sulfuric acid

• Agricultural chemicals
• Aluminum Sulfate
• Batteries
• Cellophane
• Detergents
• Explosives
• Fertilizers
• Gasoline
• Herbicides
• Iron and steel pickling
• Jet Fuel
• Kerosene
• Leather
• Lubricating oils
• Medicinal processes
• Oil additives
• Paper
• Rayon and rubber
• Sugar
• Synthetic fibers
• Veterinary drugs
• Water softener regeneration
• Water treatment
• Yellow pigments

Chemical Manufacturing

As a highly important chemical compound, sulphuric acid is used in the manufacturing process of a number of well-known chemicals including hydrochloric acid, nitric acid, phosphoric acid and many other industrial chemicals.

Oil Refining

The process of refining crude oil requires the use of an acid as a catalyst and Sulphuric acid is often used for this purpose. It is used in a SAAU or sulphuric acid Alkylation Unit.

Metal Processing

‘Pickling’ is a term used to describe the treatment of metals to remove impurities, rust or scale from the surface, such as in steel making. Today, the use of sulphuric acid for this purpose has decreased a little as the industry now favours the use of hydrochloric acid. Although hydrochloric acid is more expensive than sulphuric acid, it produces results more quickly and minimizes the loss of base metal during the pickling process.

The Manufacture of Rayon

The textile Rayon is made from cellulose fibres derived from wood. These are dissolved in a solution of Tetra Amine Copper (II) to produce a thick blue liquid which is then injected into sulphuric acid to form Rayon fibres. Rayon is considered to be a good semi-synthetic textile and can rival silk for drape and lustre. Indeed, it is sometimes referred to as ‘art silk’. It is easily dyed and the fabric is soft, cool and smooth. However, unlike silk, Rayon does not insulate body heat so is perfect for use in humid and hot countries.

The Manufacture of Lead-Acid Type Batteries

Sealed-unit lead-acid type batteries are used in the automotive industry for cars and trucks. Sealed-unit lead-acid type batteries were invented in 1859 by Frenchman Gaston Plants. Sulphuric acid is used in a dilute form to act as an electrolye to allow the flow of electrons between the plates in the battery. Sulphuric acid used in this way is commonly called Battery Acid. It can vary in strength according to the battery manufacturer but is generally between 28 to 32 per cent or between 4.2 to 5 Molar.

Potato Harvesting

Potato farmers employ specialist contractors to spray their fields of potatoes before harvesting so that the green tops die back and blacken within a day or two. This helps to dry out the stem and prevents them from becoming tangled in the harvesting equipment. The usual method of spraying potato tops is with a solution of sulphuric acid.

The Manufacture of Medicines

Chemotherapy drugs are used to treat various types of cancer. Cancer cells are more sensitive to DNA damage than normal cells so in chemotherapy treatment cancer cells are destroyed by damaging their DNA. This process is known as alkylation of DNA and a type of drug known as alkylating antineoplastic agents are used. Sulphuric acid is used in the manufacturing process of such drugs

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