SO2 scrubbing with NaOH aquas solution

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Discussion Overview

The discussion revolves around the scrubbing of SO2 from exhaust flue gas using NaOH aqueous solution. Participants explore the appropriate ratios of NaOH to water for effective scrubbing, as well as related chemical engineering considerations.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant seeks guidance on the ratio of NaOH to water for scrubbing SO2 from exhaust gas, noting a flow rate of 200 ml/min and an SO2 content of 0.25%.
  • Another participant suggests that the problem is more aligned with chemical engineering, involving mass transfer and equilibrium considerations.
  • There is a discussion about the concentration of NaOH, with suggestions ranging from 25% to 40% NaOH in water, and a participant mentions that a saturated solution of NaOH can lead to salt precipitation if water evaporates.
  • Clarification is sought regarding the solubility of K2SO4 and Na2SO4 in water at room temperature, with some participants referencing external sources for this information.
  • A later post inquires about determining the eutectic temperature of a mixture of compounds, indicating a shift in focus to another chemical property.

Areas of Agreement / Disagreement

Participants express varying levels of uncertainty regarding the appropriate NaOH concentration for scrubbing SO2, and there is no consensus on the exact ratio. Additionally, the discussion about solubility and eutectic temperatures introduces further complexity without resolution.

Contextual Notes

Participants note the importance of specific conditions such as temperature and concentration, which may affect the outcomes of their scrubbing process and solubility inquiries. There is also mention of the need for specialized handbooks for accurate data.

Who May Find This Useful

This discussion may be of interest to those involved in chemical engineering, environmental science, or anyone working with gas scrubbing technologies and solubility of chemical compounds.

HP Raj
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Hi friends, as part of my research work, I need to scrub off the SO2 content in the exhaust flue gas from a tubular furnace in my lab.

I got the information about the usage of NaOH aquas solution for the SO2 scrubbing.

Could you please suggest the ratio of water and NaOH that would be mixed together.

The flow rate of the exhaust gas mixture is 200 ml/min. The SO2 content in the gas mixture os 0.25%.

I got stuck in this portion of my project...Please help me...
 
Engineering news on Phys.org
This is more chemical engineering than just chemistry.
 
Hmmm, could you please suggest an approximate ratio...
 
HP Raj said:
Hmmm, could you please suggest an approximate ratio...
It depends on the setup. How is the contact being carried out?

Chet
 
We are planning to bubble the exhaust gas which contain SO2 through the NaOH solution in a container.
The flow rate of the exhaust gas is 200 ml/min.
The 'ppm' (Parts Per Million) of SO2 in the exhaust flue gas is 5.26.
But, the allowable ppm for SO2 is below 5 ppm.
I don't know in what ratio we need to mix the water and NaOH for scrubbing the SO2 from this exhaust flue gas.
 
As Borek said in #2, this is a chemical engineering problem involving convective mass transfer and interphase equilibrium near rising bubble interfaces. Hire a chemical engineering consultant to help you.

Chet
 
HP Raj said:
We are planning to bubble the exhaust gas which contain SO2 through the NaOH solution in a container.
The flow rate of the exhaust gas is 200 ml/min.
The 'ppm' (Parts Per Million) of SO2 in the exhaust flue gas is 5.26.
But, the allowable ppm for SO2 is below 5 ppm.
I don't know in what ratio we need to mix the water and NaOH for scrubbing the SO2 from this exhaust flue gas.

If you are already at 5.26 ppm, and you want <5 ppm, you are pretty close. The most NaOH in water you can get is 50%, a saturated solution. At that concentration you will have some salt precipitation if any water evaporates.

HP Raj said:
Hmmm, could you please suggest an approximate ratio...

So try 25-40%. NaOH in water
 
It means, for 1 ltr of water, we can go for 250 - 400 g of NaOH. Am I rt?
 
Hyo X said:
If you are already at 5.26 ppm, and you want <5 ppm, you are pretty close. The most NaOH in water you can get is 50%, a saturated solution. At that concentration you will have some salt precipitation if any water evaporates.
So try 25-40%. NaOH in water

It means, for 1 ltr of water, we can go for 250 - 400 g of NaOH. Am I rt?
 
  • #10
Not exactly, but most likely close enough.
 
  • #11
Friends, could you please let me know the solubility of K2SO4 and Na2SO4 in water at room temperature...
 
  • #12
HP Raj said:
Friends, could you please let me know the solubility of K2SO4 and Na2SO4 in water at room temperature...

Have you tried wikipedia?
 
  • #13
Yes, but in that, they have given the solubility at 20-25 Deg. C.
Can we consider this as the solubility of these chemicals at room temperature?
Am totally confused...
Please forgive my ignorance...
 
  • #14
20-25 deg C is a room temperature.

Any decent chemistry handbook will contain solubility tables, typically for different temperatures. Mine definitely has them.
 
  • #15
Friends, if we know the individual melting point of the compounds, is there any way to find out the eutectic temperature of the mixture of these compounds?
Could you please help me to find out
Borek said:
20-25 deg C is a room temperature.

Any decent chemistry handbook will contain solubility tables, typically for different temperatures. Mine definitely has them.

Thank you for the information...it worked well...
 
  • #16
Hi friends,
If we know the individual melting point of certain compounds, is it possible to find out the Eutectic temperature of the mixture of these compounds?

Could you please help me to find out the Eutectic temperature of the mixture contains K2SO4, Na2SO4, Fe2O3, Al2O3 and SiO2
 
  • #17
Please start new threads for new problems.

This is again about data that - if known - are held in tables in specialized handbooks.
 

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