Magnafloc 351 Equivalent — Nonionic Polyacrylamide

The single most common purchasing error we see on nonionic enquiries is a buyer asking for "the anionic equivalent of Magnafloc 351" because a colleague assumed all Magnafloc grades are anionic. They are not. The held BASF-attributed chart identifies Magnafloc 351 and Magnafloc 333 as nonionic while listing other 3xx grades in the same chart as anionic, so the model number alone does not tell you the charge family and cannot be read as a rule. Ordering across that boundary produces a flocculant that underdoses badly at low pH and gets written off as poor quality when the real fault was the specification.

This matters commercially as well as technically. If your circuit was commissioned on a nonionic grade, the reason is usually that someone already tried an ionic one and it failed. Acid conditions, high dissolved salt, or activated carbon in the loop are the three usual causes. Any of those three should keep you inside the nonionic family when you re-source, and none of them are visible from the grade number alone — which is why we ask for the duty rather than only the grade you are replacing.

Nonionic polyacrylamide flocculates through hydrogen bonding: the amide groups along the chain attach directly to particle surfaces and the long chain bridges particles into an aggregate heavy enough to settle. Nothing in that mechanism depends on charge, which is what makes it robust in conditions that defeat ionic grades. Anionic polyacrylamide, by contrast, relies partly on electrostatic interaction through hydrolysed carboxyl groups, and that contribution disappears as pH falls or ionic strength rises.

The honest limitation is that where charge does help, anionic outperforms nonionic on the same molecular weight. In a neutral-pH, low-salinity tailings stream with divalent calcium available to bridge, a medium-charge anionic grade will usually settle faster at a lower dose than a nonionic one. So the choice is not that nonionic is better — it is that nonionic is insensitive. Choose it when your water chemistry is hostile or variable, and choose anionic when it is stable and favourable.

A practical test that separates the two in about an hour: run parallel cylinder settling tests at your working pH, then repeat both at two pH units lower. If the anionic result collapses and the nonionic holds, your circuit needs the nonionic family regardless of what the dose comparison at working pH suggested.

The held BASF-attributed chart identifies bare Magnafloc 351 and provides no explanation of the SSK suffix. We do not have a source that confirms whether SSK marks a granulation difference, a formulation variant, or a regional specification. If you are running 351 SSK specifically, share a product label or current BASF data sheet so we can confirm the nature of the difference before nominating a supply route.

Where granulation itself is the practical question — dusting at the hopper, slow dissolution, or fish-eye formation in the make-up tank — we hold both standard and coarse granulation in our nonionic range, and the choice is answerable once we know which problem you are trying to solve. The grade number alone does not say which fault the SSK variant was chosen to fix.

Where dissolution time is the binding constraint, the fix is more often the make-up system than the polymer. A dry feeder with an undersized wetting cone will produce fish-eyes with any granulation, and a 30-minute ageing time will underperform against the 45 to 60 minutes that high molecular weight powder generally needs to reach full chain extension.

We are an independent manufacturer. We are not affiliated with, endorsed by, or a distributor for BASF, and Magnafloc is their trademark, used here only to identify the product a buyer is looking to replace. We do not claim our product is identical to theirs, because we cannot verify that without their grade-level data, which is distributed through their data sheet rather than published openly.

What we do claim is narrower and testable: we manufacture nonionic polyacrylamide across roughly 5 to 12 million daltons, the 351 position sits inside that range, and we will send a free sample so you can run the comparison yourself on your own material. Any performance claim that matters to a purchasing decision should come from that test rather than from either manufacturer's literature. Independent guidance on flocculant selection and jar-test methodology is published by the American Water Works Association and by the Water Environment Federation, and both are worth consulting if you are building a test protocol from scratch.