HEDP•Na4 (Tetrasodium 1-Hydroxy Ethylidene-1,1-Diphosphonate) Granules represent the solid, alkaline salt form of HEDP. While the liquid acid form is a standard for direct chemical blending in liquid water treatment loops, the granular solid is specifically manufactured to overcome handling, shipping, and compounding limitations.
It provides the exact same scale and corrosion inhibition as liquid HEDP but delivers specific physical and pH-related advantages.
Key Technical Properties
1. Physical & Handling Advantages
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Low Dusting & High Flowability: Unlike fine crystalline powders which cake easily, absorb moisture instantly, and create respiratory hazards during batching, the granular form flows smoothly through automatic dry feeders and hoppers.
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Excellent Water Solubility: Even as a solid granule, it dissolves rapidly and completely in water without leaving residues or clogging lines.
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Reduced Freight Costs: Trading and shipping liquid HEDP means paying for approximately 40% water content. HEDP•Na4 granules possess an active content of 85% to 90%, heavily reducing logistics costs for international and long-distance transport.
2. Chemical Properties
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Alkaline pH Profile: A 1% aqueous solution of HEDP•Na4 yields a pH of 10.0 to 12.0. This is ideal for formulations where adding a strong acid (like liquid HEDP, pH less than 2.0) would destabilize the mixture or cause unwanted chemical reactions.
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Lattice Distortion & Metal Chelation: Retains HEDP’s core performance—strongly chelating Ca2+, Mg2+, and Fe3+ ions at sub-ppm concentrations to prevent scaling up to 250°C.
Primary Applications
1. Solid-Formulation Water Treatment Compounds
Many modern water treatment service companies prefer using solid chemical blocks, sticks, or granular blends for small-to-medium cooling towers, institutional boilers, and HVAC loops to completely eliminate the hazards of liquid chemical spills. HEDP•Na4 granules are the primary choice for compounding these solid, slow-release scale and corrosion inhibitors.
2. Industrial & Daily Chemical Detergents
The alkaline nature of HEDP•Na4 makes it perfectly compatible with alkaline washing powders and solid cleaning blocks:
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Laundry Powders & Dishwasher Tablets: It acts as a built-in water softener, preventing hard-water ions from precipitating onto fabrics or glassware (which causes spotting).
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Bar Soaps: Used as a clarifying agent and rancidity stabilizer by trapping the trace heavy metals that catalyze the breakdown of fatty acids.
3. Textile Processing Auxiliaries
When compiling dry auxiliary powder kits for textile mills (such as concentrated scouring, bleaching, or dyeing kits), HEDP•Na4 granules are used as the active chelating component. It stabilizes hydrogen peroxide bleaching baths and maintains dye leveling under neutral-to-alkaline processing conditions.
4. Metal Cleaning and Electroplating Batches
Because it is already neutralized into a sodium salt, it is added directly to alkaline soak cleaners, electroplating bath makeups, and metal descaling powders where severe acidic etching of the base metal must be avoided.
Technical Specification Overview
| Property | Standard Value |
| Appearance | White granular solid / granules |
| Active Component (as HEDP) | 50.0% – 54.0% |
| Active Component (as HEDP•Na4) | 85.0% – 90.0% |
| Total Phosphorus (as $\text{PO}_4^{3-}$) | 52.0% – 54.0% |
| pH (1% Water Solution) | 10.0 – 12.0 |