HS code · 4-digit heading
HS Code 28.33 – Sulphates; alums; peroxosulphates (persulphates)
What HS 28.33 covers
HS Code 2833 encompasses sulphates, alums, and peroxosulphates (persulphates), a vast and economically significant category of inorganic chemicals. Sulphates, salts of sulphuric acid, are ubiquitous in industry. They include common compounds like magnesium sulphate (Epsom salt), calcium sulphate (gypsum), ammonium sulphate (a major fertilizer), and copper sulphate (fungicide, algicide). Their applications range from agriculture and construction to pharmaceuticals, pigments, and catalysts. Alums are a specific group of double sulphates, typically aluminum potassium sulphate or aluminum ammonium sulphate, primarily used in water purification as coagulants, in dyeing as mordants, and in leather tanning. Peroxosulphates, also known as persulphates, such as sodium persulphate and ammonium persulphate, are powerful oxidizing agents used as initiators for emulsion polymerization (e.g., in plastics production), as bleaching agents, and in etching solutions for printed circuit boards. The scope of this heading is broad, covering both chemically defined metallic and non-metallic sulphates, as well as the specialized alums and peroxosulphates. Precise classification under 2833 is crucial for accurate tariff application, adherence to agricultural regulations (for fertilizers), and compliance with environmental and safety standards, particularly for hazardous peroxosulphates. This heading, situated within Chapter 28, highlights the immense industrial importance and versatility of these sulfur-containing inorganic salts, distinguishing them by their specific chemical structures and diverse functionalities.
- Covers
- Magnesium sulphate (Epsom salt)
- Calcium sulphate (Gypsum)
- Ammonium sulphate
- Copper sulphate
- Zinc sulphate
- Ferrous sulphate
- Sodium sulphate
- Potassium sulphate
- Aluminium sulphate
- Potassium alum
- Ammonium alum
- Sodium persulphate
- Ammonium persulphate
- Potassium persulphate
- Barium sulphate
- Chromic sulphate
- Nickel sulphate
- Cobalt sulphate
- Manganese sulphate
- Lead sulphate
- Lithium sulphate
- Strontium sulphate
- Cadmium sulphate
- Aluminium potassium sulphate
- Aluminium ammonium sulphate
- Examples
A large agricultural cooperative in Brazil imports several bulk shipments of ammonium sulphate fertilizer from Russia via ocean bulk carriers to enhance crop yields. A municipal water treatment authority in the Philippines procures aluminum sulphate from a US manufacturer to clarify drinking water, typically transported in large containers. A health and wellness company in North America imports magnesium sulphate (Epsom salt) from China for bath salts and therapeutic products, usually via standard container freight. A German chemical company exports sodium persulphate to South Korea for use as a polymerization initiator in plastics manufacturing, often through specialized container shipping. An Indian construction firm imports large quantities of gypsum (calcium sulphate) from Oman for plaster and drywall production.
Subheadings under 28.33 10
Codes often confused with 28.33
Common mistake. A common misclassification involves confusing sulphates (2833) with sulphites (2832) or other sulphur compounds. For instance, sodium sulphate must be clearly distinguished from sodium sulphite. The key is the sulphate anion (SO4(2-)). Alums are specifically double sulphates, not simple sulphates. Peroxosulphates, while containing sulphur, have a distinct peroxide linkage (-O-O-) that sets them apart from simple sulphates and other oxygenated sulphur compounds. Misclassifying these can lead to incorrect duty rates, especially for products like fertilizers which may have specific tariff lines or agricultural subsidies under Chapter 31 if they are in specific forms or mixtures, or for industrial chemicals with stringent safety regulations.
Top exporters and importers of HS code 2833, 2025
In 2025, the largest exporter of HS code 2833 in UN Comtrade data was China, with 22% of world exports; the largest importer in UN Comtrade data was China, with 21% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Top exporters 2025 · share of world exports
- 1 China $1.2B 22% of world exports
- 2 Indonesia $730M 14% of world exports
- 3 South Africa $364M 6.8% of world exports
World total: $5.3B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $1.2B 21% of world imports
- 2 Japan $428M 7.2% of world imports
- 3 United States $394M 6.6% of world imports
World total: $6.0B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Questions about HS 28.33
What is HS code 2833?
HS code 2833 is a 4-digit heading in the Harmonized System that covers: Sulphates; alums; peroxosulphates (persulphates). HS Code 2833 encompasses sulphates, alums, and peroxosulphates (persulphates), a vast and economically significant category of inorganic chemicals. Sulphates, salts of sulphuric acid, are ubiquitous in industry. They include common compounds like magnesium sulphate (Epsom salt), calcium sulphate (gypsum), ammonium sulphate (a major fertilizer), and copper sulphate (fungicide, algicide). Their applications range from agriculture and construction to pharmaceuticals, pigments, and catalysts. Alums are a specific group of double sulphates, typically aluminum potassium sulphate or aluminum ammonium sulphate, primarily used in water purification as coagulants, in dyeing as mordants, and in leather tanning. Peroxosulphates, also known as persulphates, such as sodium persulphate and ammonium persulphate, are powerful oxidizing agents used as initiators for emulsion polymerization (e.g., in plastics production), as bleaching agents, and in etching solutions for printed circuit boards. The scope of this heading is broad, covering both chemically defined metallic and non-metallic sulphates, as well as the specialized alums and peroxosulphates. Precise classification under 2833 is crucial for accurate tariff application, adherence to agricultural regulations (for fertilizers), and compliance with environmental and safety standards, particularly for hazardous peroxosulphates. This heading, situated within Chapter 28, highlights the immense industrial importance and versatility of these sulfur-containing inorganic salts, distinguishing them by their specific chemical structures and diverse functionalities.
What products fall under HS code 2833?
Magnesium sulphate (Epsom salt), Calcium sulphate (Gypsum), Ammonium sulphate, Copper sulphate, Zinc sulphate, Ferrous sulphate, Sodium sulphate, Potassium sulphate, Aluminium sulphate, Potassium alum, Ammonium alum, Sodium persulphate, Ammonium persulphate, Potassium persulphate, Barium sulphate, Chromic sulphate, Nickel sulphate, Cobalt sulphate, Manganese sulphate, Lead sulphate, Lithium sulphate, Strontium sulphate, Cadmium sulphate, Aluminium potassium sulphate, Aluminium ammonium sulphate
What are common misclassifications for HS code 2833?
A common misclassification involves confusing sulphates (2833) with sulphites (2832) or other sulphur compounds. For instance, sodium sulphate must be clearly distinguished from sodium sulphite. The key is the sulphate anion (SO4(2-)). Alums are specifically double sulphates, not simple sulphates. Peroxosulphates, while containing sulphur, have a distinct peroxide linkage (-O-O-) that sets them apart from simple sulphates and other oxygenated sulphur compounds. Misclassifying these can lead to incorrect duty rates, especially for products like fertilizers which may have specific tariff lines or agricultural subsidies under Chapter 31 if they are in specific forms or mixtures, or for industrial chemicals with stringent safety regulations.
Which countries are the top exporters of goods under HS code 2833?
In 2025, the top exporters of HS code 2833 in UN Comtrade data were China ($1.2B, 22% of world exports), Indonesia ($730M) and South Africa ($364M). World exports came to about $5.3B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of goods under HS code 2833?
In 2025, the top importers of HS code 2833 in UN Comtrade data were China ($1.2B, 21% of world imports), Japan ($428M) and the United States ($394M). World imports came to about $6.0B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
How is HS code 2833 structured?
HS code 2833 is a 4-digit heading under Chapter 28 of the Harmonized System. The first 2 digits (28) identify the chapter, and digits 3-4 (33) specify the heading. This code contains multiple 6-digit subheadings for precise product classification.