PolyDADMAC vs Polyamine: Which Organic Coagulant?
PolyDADMAC and polyamine are both cationic organic (polymeric) coagulants, but PolyDADMAC is a high-charge, higher-molecular-weight quaternary ammonium polymer whose charge is pH-independent, while polyamine is a lower-cost polymer whose amine charge weakens as pH rises. Choose PolyDADMAC for tough, variable or high-turbidity water and lower doses; choose polyamine for cost-sensitive, moderate-duty clarification. Both cut the inorganic-coagulant dose and the resulting sludge.
What are organic (polymeric) coagulants?
Organic coagulants are water-soluble cationic polymers that neutralize the negative charge on suspended colloids directly — without adding metal ions. Used alone or ahead of an inorganic coagulant such as PAC, they cut chemical dose, shrink sludge volume, add no aluminium or iron, and barely move pH or alkalinity. The two dominant families are PolyDADMAC and polyamine (poly-epi/DMA).
PolyDADMAC explained
PolyDADMAC — poly(diallyldimethylammonium chloride) — is a quaternary-ammonium homopolymer. Its charge sits on a permanently quaternized nitrogen, so it is strongly and consistently cationic across the whole pH range. It is typically higher molecular weight with a narrower molecular-weight distribution than polyamine, which gives strong charge neutralization plus some bridging: excellent turbidity, color and organics removal, effective at low dose, and reliable when raw-water quality swings (storm turbidity, algal blooms).
Polyamine explained
Polyamine (epichlorohydrin-dimethylamine, "epiDMA") carries primary, secondary and tertiary amine groups. Those amines are protonated (charged) at low pH but lose charge as pH rises, so performance is more pH-dependent. Polyamine is generally lower molecular weight and lower cost, and is a strong performer for oily water, sludge conditioning and moderate-turbidity clarification where its economics win.
Head to head: charge, MW, pH and dose
PolyDADMAC's quaternary charge is stronger and pH-independent; polyamine's amine charge is pH-sensitive. PolyDADMAC is usually higher MW (better bridging, larger floc) and often works at a lower dose, while polyamine competes on price. In hybrid systems, PolyDADMAC generally outperforms polyamine, and either can be paired with an anionic PAM flocculant to grow settleable floc.
A note on NDMA and drinking water
For potable water, be aware of disinfection by-products: research shows polyamine tends to form more N-nitrosodimethylamine (NDMA) than PolyDADMAC, because the tertiary amines terminating polyamine chains are NDMA precursors, whereas PolyDADMAC lacks tertiary amines. Where NDMA is regulated, favor PolyDADMAC, control the dose, and use products certified for potable use.
How to choose
- Variable / high-turbidity / algae / cold water → PolyDADMAC (pH-independent, low dose, robust).
- Cost-sensitive, moderate-turbidity, oily water, sludge conditioning → polyamine.
- Potable water with NDMA limits → PolyDADMAC, certified grade, optimized dose.
- Maximum solids capture → organic coagulant + inorganic PAC + anionic PAM (a jar-tested three-part program).
PolyDADMAC vs polyamine at a glance
| Property | PolyDADMAC | Polyamine (epiDMA) |
|---|---|---|
| Charge type | Quaternary ammonium (permanent) | Primary/secondary/tertiary amine |
| Charge vs pH | Strong, pH-independent | Weakens as pH rises |
| Molecular weight | Higher (narrower distribution) | Lower |
| Typical dose | Lower | Higher |
| NDMA precursor | Lower | Higher |
| Relative cost | Higher | Lower |
| Best for | Variable/turbid/potable water | Cost-sensitive, oily water, sludge |
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Frequently asked questions
What is the difference between PolyDADMAC and polyamine?
Both are cationic organic coagulants. PolyDADMAC is a quaternary-ammonium polymer with a strong, pH-independent charge and higher molecular weight, so it works at lower dose and stays effective across pH swings. Polyamine (epiDMA) has amine groups whose charge weakens as pH rises; it is lower molecular weight and lower cost. PolyDADMAC also forms less NDMA.
Which organic coagulant is better for drinking water?
For potable water where N-nitrosodimethylamine (NDMA) is a concern, PolyDADMAC is generally preferred because it forms less NDMA than polyamine, which contains tertiary-amine precursors. Use a grade certified for potable contact, and optimize the dose with a jar test to avoid overdosing.
Does PolyDADMAC or polyamine need a lower dose?
PolyDADMAC usually works at a lower dose because of its stronger, pH-independent charge and higher molecular weight. Polyamine competes mainly on price and can be the better economic choice for moderate-turbidity, cost-sensitive duties or oily water and sludge conditioning.
Can organic coagulants replace PAC or alum?
They can reduce or replace inorganic coagulant in some waters, cutting sludge and adding no metal ions. In practice the best results often come from a combined program — a small dose of organic coagulant plus PAC and an anionic polyacrylamide flocculant — optimized by jar testing.
Is VCYCLETECH a PolyDADMAC and polyamine manufacturer?
Yes. VCYCLETECH supplies PolyDADMAC and polyamine organic coagulants factory-direct from China at a range of molecular weights and charge densities, ISO 9001/14001/45001 certified, with a COA on every batch, free samples and OEM/ODM service. Email sales@vcycletech.com.
About the manufacturer
VCYCLETECH is a China-based manufacturer of water treatment chemicals — coagulants, flocculants, antiscalants, scale & corrosion inhibitors, biocides, dispersants and paper chemicals — ISO 9001 / 14001 / 45001 certified, with a COA on every batch and OEM/ODM service. See our quality & certifications.
References
- Poly(diallyldimethylammonium chloride) — Wikipedia
- Polyamine — Wikipedia
- N-Nitrosodimethylamine (NDMA) — Wikipedia
Related: PolyDADMAC product · Polyamine · PAC · All coagulants & flocculants · Coagulation vs flocculation