LaCl Solution Strength

Dennis Cartier · Oct 31, 2017

The typical LaCl solution that most people use (SeaKlear) is not available in my local country. All the other ones I have found locally are not pure LaCl. I ran across a post online about someone making their own LaCl using Reagent Grade LaCl, but can't find the post at the moment.

I ordered in some reagent grade 99.5% LaCl3 7H2O from a supplier in China. I just want to double check the impurities and get a confirmation of the mixture strength.

The impurities are:

SO4 - o.oo5
Fe - 0.002
Pb - 0.002
CeO2 - 0.2

The first 3 would seem to be reasonable, but the last one, cerium dioxide, that I am unfamiliar with. Any risk to having trace amounts of this element in the solution?

Now for the mixing strength. I was thinking of making a stock solution of 9g of LaCl/Litre, which if I am right, should give me 9000 ppm or 9 mg/ml stock solution.

I noticed the seaklear product mentions it removes 9000 ppb orthophosphate in 10,000 gallons. I am just trying to figure out how my planned stock solution would compare to the commercial product. Knowing that would make dosing easier as that strength is what is commonly used (after being diluted even more).

Feedback on my calculations for strength would be great.

Dennis

Randy Holmes-Farley · Oct 31, 2017

I have no reason to worry about those levels of impurities.

I'm not sure how pure the stuff most people actually use is, but not likely as pure as yours.

Randy Holmes-Farley · Oct 31, 2017

Dennis Cartier said:
Feedback on my calculations for strength would be great.

Dennis

I have no idea what assumptions hobby companies make to determine how much phosphate their product will remove, but I also expect it isn't very accurate since they probably assume lanthanum phosphate is the only product (it likely isn't).

Randy Holmes-Farley · Oct 31, 2017

As a rough guide, your product is about 37% lanthanum by weight.

If it all precipitated lanthanum phosphate, then each gram of actual lanthanum would precipitate about 0.7 grams of phosphate.

So 1 gram of your product will precipitate 0.26 grams of phosphate, or 2.6 ppm from 100 L of water.

Dennis Cartier · Oct 31, 2017

Randy Holmes-Farley said:
As a rough guide, your product is about 37% lanthanum by weight.

If it all precipitated lanthanum phosphate, then each gram of actual lanthanum would precipitate about 0.7 grams of phosphate.

So 1 gram of your product will precipitate 0.26 grams of phosphate, or 2.6 ppm from 100 L of water.

Thanks Randy. That really helps.

Dennis