If you’ve come across the term aluminium potassium sulfate formula while sourcing a potassium-rich compound for your agricultural or industrial operation, you might be wondering whether it’s the same high-purity potassium sulfate you need. The short answer is no. Aluminium potassium sulfate—commonly known as potash alum—has the chemical formula KAl(SO₄)₂·12H₂O (or sometimes the anhydrous form KAl(SO₄)₂), while potassium sulfate, the premium chlorine-free fertilizer and industrial chemical, is simply K₂SO₄. Despite the similar names, these two compounds have distinct chemistries, physical forms, and end-use applications. In this guide, we’ll break down the aluminium potassium sulfate formula, explore its uses and safety data, and clarify how it differs from the sulfate of potash that procurement managers in agriculture, glass manufacturing, aluminum recycling, and pharmaceuticals rely on every day.
The aluminium potassium sulfate formula most commonly encountered is the dodecahydrate: KAl(SO₄)₂·12H₂O. In its anhydrous state, it is KAl(SO₄)₂. This double sulfate salt crystallizes in regular octahedra and has been used for centuries in water purification, textile dyeing, leather tanning, and even as a component in baking powders. The compound contains roughly 10–11% alumina (Al₂O₃), 9–10% potassium oxide (K₂O), and the balance sulfate and water of crystallization. It is frequently sold in lump, crystal, or powder form and is widely available from chemical distributors worldwide.
In contrast, potassium sulfate (K₂SO₄) contains no aluminum. It is a binary salt with a typical K₂O content of 50% minimum, making it one of the most concentrated potassium sources available for chloride-sensitive crops like tobacco, potatoes, citrus, and grapes. The aluminium potassium sulfate formula is fundamentally different, which dictates its completely separate set of industrial applications.
Confusing these two chemicals can lead to costly procurement errors. Below is a side-by-side comparison of their essential properties.
Alum dissolves readily in water, forming a slightly acidic solution (pH 3–4) due to hydrolysis of the Al³⁺ ion. Potassium sulfate dissolves slowly and yields a near-neutral solution, making it compatible with sensitive irrigation systems.
The confusion arises primarily from overlapping terminology. The word “potassium sulfate” in both names is misleading; aluminium potassium sulfate is often listed on supplier websites simply as “potassium aluminum sulfate” or “alum,” and many international trade platforms group it under sulfate salts. A procurement officer searching for “potassium sulfate” for fertilizer may inadvertently land on listings for alum. Additionally, in some languages, “sulfate of potash” is loosely used, further blurring the lines.
When sourcing, always request the CAS number and full chemical formula. The CAS for anhydrous aluminium potassium sulfate is 10043-67-1, for the dodecahydrate it’s 7784-24-9. Potassium sulfate (SOP) has the CAS number 7778-80-5. Verifying these identifiers eliminates ambiguity during the purchasing process.
Understanding what alum is used for helps clarify why it shouldn’t be substituted for SOP. Key industrial applications include:
None of these uses overlap with potassium sulfate’s role as a chlorine-free fertilizer, glass fining agent, or pharmaceutical excipient—reinforcing why correct product identification is critical.
Many buyers search for an aluminum potassium sulfate SDS when assessing handling requirements. The Safety Data Sheet for alum highlights:
In comparison, the SDS for high-purity potassium sulfate from Hailei Chemical indicates a non-hazardous substance with no special ecological risks when handled as recommended. Neither compound is classified as dangerous goods for transport. Nevertheless, always refer to the manufacturer’s SDS for the specific grade you purchase.
While alum contains potassium, what is potassium sulfate fertilizer exactly? It’s a binary source of potassium (K) and sulfur (S) with zero chloride. The K₂SO₄ molecule delivers 44–46% K₂O (Hailei Chemical guarantees 50% minimum) and 18% sulfur. This combination makes it indispensable for:
For specialty fertilizer importers, sourcing SOP with guaranteed analysis and consistent granule size is a business-critical decision. Hailei Chemical’s sulfate of potash meets international standards, with options in powder, granular, and soluble crystal forms.
When exploring the price potassium sulfate market, it’s essential to understand what drives variability. Unlike aluminium potassium sulfate, which is relatively inexpensive due to its broad manufacturing base, SOP pricing reflects these key factors:
Procurement managers should always request a full specification sheet alongside the price quotation to ensure you’re comparing like-for-like grades. The aluminium potassium sulfate formula might be cheap, but it cannot replace the agronomic or industrial performance of genuine SOP.
Your question how is potassium supplied goes to the heart of chemical sourcing. Potassium for agricultural use is primarily supplied as muriate of potash (KCl), sulfate of potash (K₂SO₄), and potassium nitrate (KNO₃). For industrial applications like glass manufacturing, aluminum recycling, and pharmaceuticals, SOP is the preferred form because of its purity and lack of corrosive chloride ions.
As a leading exporter, Hailei Chemical supplies potassium sulfate in multiple forms:
In contrast, aluminium potassium sulfate is rarely, if ever, used to supply potassium because the aluminum ions would be phytotoxic and counterproductive. It remains a specialty chemical for water treatment and niche industrial processes.
A unique angle that often surprises buyers is the role of K₂SO₄—not alum—in aluminum recycling. When melting aluminum scrap, a molten salt flux is used to protect the metal from oxidation and to strip away impurities. Potassium sulfate, combined with sodium chloride in precise ratios, forms a low-melting eutectic that floats on the melt surface. The aluminium potassium sulfate formula is entirely unsuitable here because its hydrated form would violently decompose at the high temperatures of molten aluminum (≈700°C), releasing steam and disrupting the process. Only anhydrous K₂SO₄ provides the thermal stability required.
Similarly, in glass manufacturing, potassium sulfate serves as a refining agent. It reduces furnace temperature and eliminates bubbles, improving the clarity of high-quality container and optical glass. The absence of chloride ensures no corrosive attack on the furnace lining or color deviation in the final product. This is an application where Hailei Chemical’s consistent particle size distribution and high purity directly translate to cost savings for glass producers.
The pharmaceutical industry uses potassium sulfate as an excipient in sustained-release tablets and as a component of oral rehydration salts. The rigorous requirements—heavy metal limits, microbial purity, and compliance with pharmacopeia monographs—demand a supplier with robust quality management systems. This is not a market that aluminium potassium sulfate can serve. Alum’s astringent properties and aluminum content make it pharmacologically active in ways that are undesirable for most drug formulations.
Hailei Chemical’s SOP meets USP/EP specifications, and our customers in the pharmaceutical and food supplement sectors value our batch-to-batch consistency and comprehensive certificates of analysis. If your application demands the finest potassium sulfate, our technical support team can guide you through the grade selection process.
With over two decades of experience in the fine chemical export sector, Weifang Hailei Fine Chemical Co., Ltd. understands that B2B buyers need more than a low price—they need a partner who ensures supply security, regulatory compliance, and technical expertise. Our potassium sulfate is produced under strict ISO 9001 quality management, and each shipment is accompanied by a detailed COA, packing list, and, if required, a certificate of origin.
The aluminium potassium sulfate formula (KAl(SO₄)₂·12H₂O) defines a compound with a rich history in industrial chemistry, but it is not a substitute for potassium sulfate (K₂SO₄) in agriculture, glass, aluminum recycling, or pharmaceuticals. By clearly understanding these differences and verifying CAS numbers, buyers can avoid costly mistakes and secure the precise material their operations demand.
Ready to source premium chlorine-free potassium sulfate from Hailei Chemical? Whether you need a container load for your fertilizer blending facility or a full truckload of industrial-grade SOP for glass production, our team is here to deliver. Request a quotation today and let’s discuss your specifications, volume requirements, and delivery timeline—backed by the technical support and consistent quality that global buyers trust.