Scientists Figure Out New Way to Remove Salt From Water Giving Hope to Oil and Gas Industry

Sounds like good news for both the Oil & Gas industry and for the Environment.  Win - Win.

Scientists Figure Out New Way to Remove Salt From Water Giving Hope to Oil and Gas Industry

The solvent-based method could be much cheaper to use than reverse osmosis or distillation based on water evaporating.

Brine water produced by the oil and gas industry contains even more dissolved salts than ocean water, and is a growing environmental concern - but scientists have figured out a new way to treat it.

These hypersaline brines can pollute the fresh water resources which communities depend on, and are difficult to treat.

But a team of engineers from Columbia University in the US say they have now developed a radical new approach to desalinating them.

The method, known as "temperature swing solvent extraction" (TSSE), involves mixing the hypersaline brine with an amine solvent.

Scientists say the method can desalinate very high-salinity brines, up to seven times the concentration of seawater. This is more than both the method currently used for seawater desalination, known as reverse osmosis, and the water evaporation method can achieve.

The method was published in the scientific journal Environmental Science & Technology Letters.

Once it is mixed in the brine, the solvent, which is less dense, is lifted to the top of the brine.

The mix is then placed on a room temperature bath to help complete the water extraction - and after that the solvent is decanted from the mixture.

A warm water bath then provides a temperature swing which de-mixes the processed water from the solvent - because the solvent is less able to hold water at higher temperatures.

When the solvent releases the water, it sinks to the bottom of the bottle - from where it can be collected.

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Tom, here is the single most fascinating part of this concept, which I quote from the article:

    " Crucially, the solvent method is powered by low-grade heat, under 70C (158F), meaning it is far less energy-intensive to use, and can remove up to 98.4% of the salt in these brines and recover high amounts of water."

Now that is fascinating.  It implies that this method could be used either in conjunction with osmosis for drinking water from seawater, or as a replacement for the osmosis protocol.  Either way, the dramatic drop in energy use will make drinking water cheaper.  And, as an added bonus, that "low-grade heat" is easily extracted from the hot desert sun, so places from Morocco to Yemen can have lots of fresh water simply by using solar reflectors to heat up the water.  Build a half-pipe concentrator out of shiny sheet metal, and you are all set!

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Interesting article, thank you for sharing Tom.

I only delved into thermodynamics enough to learn that you can't break the rules...

From the paper abstract...

This study demonstrates TSSE desalination of high-salinity brines simulated by NaCl solutions with three amine solvents: diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), and N,N-dimethylcyclohexylamine (DMCHA)

This is definitely an interesting chemical engineering technology, but I am left asking these questions:

1) What volume of solvent is required for reaction of desalinate a given amount of water at a given salinity?

2) How much reaction energy is required on the front end in manufacturing the solvent? I saw that DMCHA costs about $80 a liter...

3) What other incidental costs/risks (aside from energy input) are associated with manufacturing and using the solvent (e.g., toxicity/treatment costs of properly mitigating public health risk posed by solvents and by-products).

For what it's worth, pretty sure the supply chain for all these solvents involves Chinese manufacturing.

 


 

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On ‎5‎/‎13‎/‎2019 at 11:50 AM, Jan van Eck said:

Tom, here is the single most fascinating part of this concept, which I quote from the article:

    " Crucially, the solvent method is powered by low-grade heat, under 70C (158F), meaning it is far less energy-intensive to use, and can remove up to 98.4% of the salt in these brines and recover high amounts of water."

Now that is fascinating.  It implies that this method could be used either in conjunction with osmosis for drinking water from seawater, or as a replacement for the osmosis protocol.  Either way, the dramatic drop in energy use will make drinking water cheaper.  And, as an added bonus, that "low-grade heat" is easily extracted from the hot desert sun, so places from Morocco to Yemen can have lots of fresh water simply by using solar reflectors to heat up the water.  Build a half-pipe concentrator out of shiny sheet metal, and you are all set!

That would take sea water down to about 600mg/litre which would be reasonable quality potable water providing the solvent can be completely removed.

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On 5/13/2019 at 11:48 PM, esgeo said:

Interesting article, thank you for sharing Tom.

I only delved into thermodynamics enough to learn that you can't break the rules...

From the paper abstract...

This study demonstrates TSSE desalination of high-salinity brines simulated by NaCl solutions with three amine solvents: diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), and N,N-dimethylcyclohexylamine (DMCHA)

This is definitely an interesting chemical engineering technology, but I am left asking these questions:

1) What volume of solvent is required for reaction of desalinate a given amount of water at a given salinity?

2) How much reaction energy is required on the front end in manufacturing the solvent? I saw that DMCHA costs about $80 a liter...

3) What other incidental costs/risks (aside from energy input) are associated with manufacturing and using the solvent (e.g., toxicity/treatment costs of properly mitigating public health risk posed by solvents and by-products).

For what it's worth, pretty sure the supply chain for all these solvents involves Chinese manufacturing.

Good questions, esgeo.  I'm not the correct person to answer them though, as I am not a chemical engineer.

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