## Chemical Dosing Rate Calculation - Acid Water Neutralisation

## Chemical Dosing Rate Calculation - Acid Water Neutralisation

(OP)

Hi All,

Looking for some assistance on a relationship/calculation to determine the caustic dosage rate required into a certain flow rate of acid water so as to neutralise it to a certain pH. If you refer to the attached sketch, it shows the parameters i am looking to get a relationship for. Hopefully i have the correct variables covered but let me know if not

Cheers

Looking for some assistance on a relationship/calculation to determine the caustic dosage rate required into a certain flow rate of acid water so as to neutralise it to a certain pH. If you refer to the attached sketch, it shows the parameters i am looking to get a relationship for. Hopefully i have the correct variables covered but let me know if not

Cheers

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

But if you started with something other than ultrapure water and ultrapure sodium hydroxide, you will need more information about what else is in the water to accurately estimate how much acid is required to get you from pH 9 down to 7-8.

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

Thanks

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

## RE: Chemical Dosing Rate Calculation - Acid Water Neutralisation

pH = - log10 [ H⁺ ] …………………..①

pOH = - log10 [ OH⁻ ] ……………..②

pH + pOH = 14 ……………………..③

Your inlet water pH is 2. According to formula ① ,

H⁺= 10⁻² mol ̷ L

Suppose the inlet flow is 50 m3 ̷ h .

So the H⁺ flow rate , 10⁻²mol ̷ L X 50 m3 ̷ h X 1000 = 500 mol ̷ h

To bring the pH 2 to 7( neutral zone) , you need to dose NaOH in the rate of 500 mol ̷ h.

Molarity of NaOH is 40.01 mol ̷ L .When the Caustic strength diluted to 50 % ,

The molarity will be 40.01 mol ̷ L X 50 % = 20 mol ̷ L

The dosing rate of NaOH =( 500 mol ̷ h) ̷ (20 mol ̷ L )

= 25 L ̷ h

Like wise you can calculate the dosing rate for alkali water using ② and ③ formulas. But keep in mind that these are just theoretical , the actual could vary due to numerous reasons.