Sulphuric acid is a dense, strongly acidic liquid made by dissolving sulphur trioxide in water. Usually colourless to pale amber, it mixes readily with water and releases heat, so dilution must be controlled. Its reactivity underpins processes from fertilisers to batteries.
Properties and Production
Typical grades are 93 to 98 percent. The contact process burns sulphur or smelter off-gas to sulphur dioxide, oxidises it to sulphur trioxide, then absorbs it in water. High acidity and affinity for water make the acid a useful catalyst, dehydrating agent and electrolyte.
Where Sulphuric Acid Is Used
Most output feeds phosphoric acid and phosphate fertilisers. It also drives refinery alkylation, leaches metals in hydrometallurgy, treats pulp, and sets dye bath pH. Lead-acid batteries use it as the electrolyte, and it helps make detergents, pigments and pharmaceuticals.
Sulphuric Acid Anodising and Surface Finishing
Aluminium forms a controlled oxide during sulphuric acid anodising, producing a hard, porous layer that can be sealed or dyed. The method improves wear resistance, corrosion protection and paint adhesion on housings, fixtures and aerospace parts.
To learn more about sulphuric acid anodising, check out a specialist, such as https://www.poeton.co.uk/surface-treatments/anodising/sulphuric-acid-anodising.
Handling, Storage and Environmental Notes
Always add acid to water when diluting, wear suitable PPE, and specify compatible materials such as PTFE, PVDF and selected rubbers for gaskets and linings. Store in labelled containers with bunding and ventilation. Neutralise small spills with carbonate or bicarbonate, then dispose through approved routes. Clear procedures and trained staff keep operations compliant while minimising risks to people and equipment.