Hi All, I am adding a KMnO4 chemic

[drogones12]

Hi All,
I am adding a KMnO4 chemical feed to my filtration compact package unit for the iron and manganese removal. I have a 50 gallon mixing day-tank and will be using powder KMnO4 for the solute to get 2% strength solution. The CAIROX potassium permanganate powder is 97% guaranteed with 2.703 g/cm^3 specific gravity. I've used the PADEP chemical calculator and got 0.451 lb/gallon solution as the result. So I would use 0.451 lb/gallon X 50 gallon = 22.55lb for 1 batch of my solution. Is this correct? Is there a formula to calculate the amount of KMnO4 that I need to be using? Thank you for your input.
thread164-432736

 

[coloeng]

Water weighs 8.34 lbs per gallon, for 50 gallons that would be 417 lbs. If you want a 2% solution, 2% of 417 lbs is 8.34 lbs. If the KMnO4 is 97%, divide the 8.34 by .97 to get 8.6 lbs for the 50 gallons.

 

[bimr]

Since you are already familiar with the PADEP, use the calculator on their page:

 

[drogones12]

I plan to add KMnO4 solution at my water treatment plant for Mn and Fe removal. Will this oxidation reaction make the water more acidic? I do use Sodium Bicarb for pH and alkalinity control.
Please see the half-reaction in the attachment. It seems the oxidation process will consume OH- and generate H+.

 

[bimr]

Permanganate quickly oxidizes Fe2+ and Mn2+ in most cases without pH adjustment. The freshly precipitated manganese floc will further adsorb metal ions and organic compounds while enhancing the effectiveness of the coagulation process.

Potassium permanganate is a salt of permanganic acid. Permanganic acid is a strong acid that is also a strong oxidizer and its reaction with potassium hydroxide yields potassium permanganate. The two neutralize each other giving a neutral base which is potassium permanganate.

In water, the permanganate dissociates into K+ and MnO4- ions, in turn forming KOH and HMnO4, giving a neutral solution.

Salt do not have either H+ or OH-. They modify the PH of water using H+ and OH- from the water.

H2O ————-> H+ + OH-

A salt dissociates into its constituent in water.

KMnO4 —————→ (K)+ + (MnO4)-

Now they will react with water and will form respective base and acid.

K+ + OH_ —————→ KOH

H+ + MnO4- —————→ HMnO4

KOH is a strong base and all OH- ion will be available freely.

HMnO4 is a weak acid, some H+ ion of this will be bound to the anion.

As a result, there will be lesser H+ then normal water. So PH will be above 7.

Carus