[cjwater2]

Hello -

I work at a water treatment plant.  We haul 50 lb. bags of calcium hydroxide into large tanks to raise the ph of the water.  We do this about 100 times a day and it is grueling.  I read somewhere that there is concentrated calcium hydroxide, and I also read that adding sucrose to the mix increases the ph...

I was wondering what the solution would be to make it so we that had to add less lime.  Or even a different compound that would work with the setup set up for the lime.  Does an ultra dense mixture exist that would only require a small amount to be added to the water or limewater?  Does anyone have any thoughts on this problem at all?

Any help is super appreciated.

Thank you a million times.

Best,

CJ

[Arkcon]

The great thing about lime is that its very cheap, and very alkaline.  Although insoluble, a large quantity will make a large volume of water alkaline, which is what's needed for water treatment.  Something like sodium hydroxide would work, and you would need much less.  But if the volume of water is huge, sodium hydroxide would be too expensive.

[Borek]

AFAIK there is no such thing as "concentrated calcium hydroxide". Slaked lime - being solid - is about as concentrated as you can get.

Perhaps you can use burnt lime - CaO - that would mean using about 75% mass of the slaked lime, but adding CaO to water means evolving heat, which can pose a problem (and the difference in mass is not that large).

[cjwater2]

Thank you for the responses.  What would happen if you added sucrose to the mixture?  How would it be added?

Thanks again,

CJ

[Arkcon]

Sucrose doesn't affect pH.  I don't know where that is from.

[cjwater2]

I read somewhere online that sucrose raises the ph in limewater.  Clearly that could be wrong.  I am not a chemist (although I would like to one day be) I am working at a water treatment facility and am interested in a quick fix.  Sodium hydroxide is a whole new ball of wax, I am looking for something that would work under existing conditions.  Burnt lime is interesting but there would be no way to use heat to add it to the large tanks of water.  I am searching (in vain mostly) for an ingenius solution to avoid adding hundreds of 50 lb bags of lime everyday.


Thanks to all,

CJ

[curiouscat]

Sucrose doesn't affect pH.  I don't know where that is from.

I think I know where that came from. The connection of sucrose and lime is that sucrose is one of the few things that can boost the solublity of slaked lime almost a 100 fold.

Useless in a water treatment context but useful elsewhere.

If solubility went up I guess pH would too? Don't know.

[Borek]

Could be there is some kind of complex created in the presence of sucrose, that could increase lime solubility - and increase liberation of OH^-.

But I am just guessing.

[curiouscat]

Could be there is some kind of complex created in the presence of sucrose, that could increase lime solubility - and increase liberation of OH^-.

But I am just guessing.

Possibly apocryphal, but one WW-II era sabotage strategy I've heard of was to throw in sugar into setting concrete.

Dunno if that works. Apparently strength is severely degraded.

[consul]

If adding sucrose to lime were to increase the solubility of lime, then it would mean an increase in the concentration of OH- ion, and consequently, an increase in the pH.

That's my take on it. Correct me if I'm wrong.

*From what I read adding sucrose increases the rate of dissolution of Ca(OH)2 in water. Increasing the rate of dissolution does not mean an increase in solubility. It simply means that it dissolves the lime faster. But, as to how much lime is dissolved, that is limited by the solubility, which is affected by temperature (in this case, an increase in temperature decreases the solubility).  Hence, the increase in pH is not guaranteed by increasing the rate of dissolution, but an increase of solubility does increase the pH.

I think I know where that came from. The connection of sucrose and lime is that sucrose is one of the few things that can boost the solublity of slaked lime almost a 100 fold.

Useless in a water treatment context but useful elsewhere.

If solubility went up I guess pH would too? Don't know.

[curiouscat]

*From what I read adding sucrose increases the rate of dissolution of Ca(OH)2 in water. Increasing the rate of dissolution does not mean an increase in solubility. It simply means that it dissolves the lime faster. But, as to how much lime is dissolved, that is limited by the solubility, which is affected by temperature (in this case, an increase in temperature decreases the solubility).  Hence, the increase in pH is not guaranteed by increasing the rate of dissolution, but an increase of solubility does increase the pH.

Unfortunately I don't have a reference at hand but it enhances solubility too. Not just rate.

Maybe this:

http://books.google.co.in/books?id=ssltAbEO4kkC&lpg=PA227&ots=rigzJq1k_s&dq=sucrose%20enhances%20solubility%20of%20lime&pg=PA227#v=onepage&q&f=false


Or this :

"The addition of sugar to the lime solution results in an enormous increase in the solubility of lime through the formation of an intermediate product, calcium succrate. "

http://www.cheneylime.com/limefact.htm

Or here:

http://books.google.co.in/books?id=zNicdkuulE4C&lpg=PA563&ots=Nitct-E4tc&dq=sugar%20%20solubility%20of%20lime&pg=PA563#v=onepage&q&f=false

[cjwater2]

Thank you again for all of your thoughtful responses.  So the next question becomes implementation...  About how much sucrose would you add to an approximately 748 gallon tank of limewater?  Are there any negative consequences to adding sucrose to a mixture that is getting pumped into pipes that lead to water mains?  Would the pumps be affected?  When would be the optimal time to add the sucrose, before or after the lime?  The tanks are being constantly mixed by a motor arm.  Clearly I will go through the proper channels before experimenting, but if this experiment proves successful it would be a life saver.  So again, much thanks, everyone has been really kind.

Best,

CJ

[billnotgatez]

Why is adding sugar not added to water treatment plants as a mater of course and be a well published procedure.
You might want to rethink this before propose it.

@cjwater2
What happens to the water once you treat it? Where does the output go?

[curiouscat]

Thank you again for all of your thoughtful responses.  So the next question becomes implementation...  About how much sucrose would you add to an approximately 748 gallon tank of limewater?  Are there any negative consequences to adding sucrose to a mixture that is getting pumped into pipes that lead to water mains?  Would the pumps be affected?  When would be the optimal time to add the sucrose, before or after the lime?  The tanks are being constantly mixed by a motor arm.  Clearly I will go through the proper channels before experimenting, but if this experiment proves successful it would be a life saver.  So again, much thanks, everyone has been really kind.

Best,

CJ

I sure would not add it. In water treatment it'd make no sense.

[cjwater2]

Thanks again for all of your help.  Before I proposed the idea I wanted to research it.  It is not common practice.  But I wonder why.  If it increases solubility and ph as a result, then would save thousands of dollars per month plus many hours of man power...