Neutralizing Chlorine: How Does It Work?

[dingpud]

Hopefully this is not an ignorant question, but does anyone know what neutralizes chlorine? I looked it up in my old college Chem book, and the only thing that I could fined regarding chlorine was that it is used to purify and clean water so that water born diseases would be neutralized. Anyway, if anyone knows what neutralizes chlorine, I would appreciate it.

Thanks again.

 

[Moonbear]

From what I've found, it seems calcium carbonate is used to neutralize chlorine spills.

 

[Bystander]

It depends a lot on what you mean when you say "neutralize," and on what you mean when you say "chlorine." Elemental chlorine is a strong oxidizer, very reactive toward a list of materials I'm not going to bother hunting down at the moment, and "neutralize" in such a context means you're going to react it with something in a controlled fashion to produce something more innocuous than chlorine --- dissolve it in lime water or a lye solution to get hypochlorite (bleach) which is still reactive, results in chemical burns to the skin and eyes. Then let the bleach solution "chew" on some organic material for a while --- get inorganic chlorides, few organic chlorides, a nasty letter or two from the EPA. Adsorb it on charcoal, bury the charcoal, and still get nasty letters from the EPA. Or, recognize that chlorine is a gas at STP (heavy, and tends to hug the ground when in high concentrations), and let it dissipate into the atmosphere --- bring in the FD's ventilation fans and portable stacks to loft it upward, and get yet another nasty letter from the EPA.

 

[Gokul43201]

Yes, as Bystander has mentioned, this depends on what you mean by "neutralize" and what the specific application involved is.

If you are, in fact talking about water purification, then the effect of chlorine is to make the water acidic $Cl_2 + H_2O \longrightarrow HCl + HOCl$. This acidity can be neutralized by a suitable base. I'm not sure what the current standard is, but about a decade ago, ammonia was commonly used as the neutralizing base.

 

[dingpud]

All sounds good

This question originally had started when someone at my work had asked me how to neutralize chlorine? I didn't have an answer, so I figured that I would turn to my friends at Physics/Chemistry forums to find the answer. I am goig to talk with him and share the results that you have posted. Thank you very much for your feedback, it is much appreciated.

Scott
-----------------------------------------------------------------------------
Please support our troops.

 

[chesterdaly]

The chemical processes for extraction of chlorine gas

Chlorine can be manufactured via the electrolysis of a sodium chloride solution, ie. brine. There are three methods for the extraction of chlorine by electrolysis used industrially.

Mercury cell electrolysis Mercury cell electrolysis was the first method used to produce chlorine on an industrial scale. Titanium anodes are located above a liquid mercury cathode, a solution of sodium chloride is positioned between the electrodes. When an electrical current is applied chloride is released at the titanium anodes, whilst the sodium dissolves into the mercury cathode forming an amalgam.

The amalgam can be regenerated into mercury by reacting it with water producing hydrogen and sodium hydroxide. These are useful byproducts.

This method consumes vast amounts of energy and there are also concerns about mercury emissions.

Diaphragm cell electrolysis An asbestos diaphragm is deposited on an iron grid cathode preventing the chlorine forming at the anode and the sodium hydroxide forming at the cathode from re-mixing.

This method uses less energy than the mercury cell, but the sodium hydroxide is not as easily concentrated and precipitated into a useful substance.

Membrane cell electrolysis The electrolysis cell is divided into two by a membrane acting as an ion exchanger. Saturated sodium chloride solution is placed in the anode compartment whilst distilled water is placed in the cathodes compartment.

This method is nearly as efficient as the diaphragm cell and yet produces very pure sodium hydroxide.

http://www.answers.com/chlorine

 

[SpaceTiger]

http://www.answers.com/chlorine

Do you work for that site or something?

 

[chesterdaly]

Do you work for that site or something?

No, I'm only in 11th grade silly. But I'm bored tonite and avoiding homework and working on my science project. I'm just surfing the net and came across that site so thought I'd share it. How do I get the smiley face to work on here? I keep clicking on the faces and it doesn't show up and when I make my own face it doesn't show the icon :) <---- see no icon

 

[chem geek]

Chlorine can be most easily neutralized by adding a reducing agent such as sodium thiosulfate. It can also be removed by exposure to ultraviolet light such as from sunlight, though this will take longer if the water contains Cyanuric Acid (CYA) that shields chlorine from sunlight (CYA absorbs UV) and also combines with chlorine to form chlorinated cyanurates that are more resistant to breakdown from UV. So removing chlorine from an outdoor pool takes longer -- a few days usually -- while removing it from tap water is easy by just exposing it to sunlight for even a few hours.

Chlorine can also be removed through filtration processes such as carbon block (activated carbon) filters. The same is true for monochloramine which is also used as the residual disinfectant by some water utilities.

Richard

 

[chroot]

Please do not resurrent ancient threads. Thanks.

- Warren