Posted on 07/09/2021 1:41:29 PM PDT by blam
Could the holy grail of turning salt water to drinkable water finally be upon us?
A new report from Interesting Engineering seems to suggest that could be the case – detailing a new nanofiber membrane, developed by Yunchul Woo and his team at the Korea Institute of Civil Engineering and Building Technology, that appears to be “stable in the long term” for desalinization. And it can be done “in minutes”, the report says.
Membranes had been used in the past, but there is often a challenge in keeping them dry for long periods of time. When they become wet, their filtration characteristics become ineffective and large amounts of salt can pass through.
Woo’s team has created a membrane “made of nanofibres that have been fabricated into a three-dimensional hierarchical structure” by using a technology called “electrospinning”. This new membrane is said to be highly water repellant.
Water from one side is heated and allows water vapor to pass through the membrane, which is then condensed on the other side. The process is called membrane distillation.
“Since the salt particles are not converted to the gaseous state, they are left out on one side of the membrane, giving highly purified water on the other side,” the report says.
It also notes that the researchers used silica aerogel in their membrane fabrication process.
Upon testing the technology for 30 days continuously, they found the membrane filtered out 99.9% of salt without wetting problems.
Desalinization is the obvious answer to the global issue of over 785 million people lacking clean drinking water. Up until now, scientists have been unable to figure out a quick, cost-efficient and effective way to turn salt water into drinkable water.
Fresh water only accounts for 2.5% of the total water available on Earth, the report notes.
Too much salt leftover? The Morton company would suppress that./s
There are several ways to desalinate seawater. The problem is to do so quickly and economically. Heating seawater then cooling and capturing the condensate takes too much energy to be really efficient. Perhaps these membranes, if they can be produced cheaply and will stand up to a large volume of water, are the answer. The problem still remains of disposing of the slurry of salt and other minerals. Currently most desalination plants return the sludgy, salty leftovers to the water supply, which is highly destructive of the environment.
I believe Union Carbide had this process back in the 70s.
Getting the water separated out is only one-half the cost battles for desalinization. The other half has been dealing with the brine collected in the process. Yes, getting the first step’s costs down will help (as they will be with more efficient filters from more efficient materials), but in the long run the second problem - dealing with the leftover brine - needs much improvement as well.
Well, if we desalinize a lot of ocean water, that will take care of the rising ocean levels.
Sounds like you don’t have to boil the water as you do in distillation, so it would require a lot less energy.
Duh!!! Well yeah! .. of course .. if you use a nanofiber membrane!
Heard about electrospinning back in the 1990’s, it is really interesting technology which is largely relegated to medical textiles such as wound dressings. We’ve done it where I work but decided not to enter the market for which the fabric was intended.
Its basic problem is that it makes fabric very slowly compared to traditional techniques. If they could spin the fibers using the “islands-in-sea” technology you could get similar diameter fibers (we’re talking nanofibers with both technologies, often less than 100 nanometer fiber diameter).
Guess they used electrospinning because it is inexpensive to set up. Hopefully they can scale this thing up and everyone with a boat on the ocean could carry the device in case of emergency.
The latent heat of vaporization doesn’t change.
I understand that, but it is kind of interesting. The purified water recovered doesn't disappear from the water cycle, but is used and eventually reenters the cycle at some point, and that would include the oceans. In other words, the water your remove from the ocean eventually finds it's way back.
So, if you don't dispose of the salt and minerals recovered back into the ocean, won't that eventually throw off the salinity of the oceans by making them less salty than they should be?
Someone could invent a process that uses C02 and Skittles to produce limitless fresh water and the greenies would still ban it.
I take it you aren’t aware that water evaporates despite the dreaded “latent heat of vaporization?”
Correct.
Doesn't this process bypass the vaporization phasechange?
Yes but consider what is in that brine from the ocean...many usable and extractable minerals and metals in a concentrated form...economical? Perhaps the researchers will discover.
“I take it you aren’t aware that water evaporates despite the dreaded “latent heat of vaporization?””
Please educate me ...
Well, they heat it up, maybe not to boiling, but enough to create steam...
From the article:
Water from one side is heated and allows water vapor to pass through the membrane, which is then condensed on the other side.
Put a dish of water on your kitchen table for a few days and get back to me.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.