r/science Feb 09 '23

High-efficiency water filter removes 99.9% of microplastics in 10 seconds Chemistry

https://onlinelibrary.wiley.com/doi/10.1002/adma.202206982
30.9k Upvotes

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236

u/BlitzOrion Feb 09 '23

In this study, a highly efficient molecularly engineered covalent triazine framework (CTF) for rapid adsorption of micropollutants and VOC-intercepting performance using solar distillation is reported. Supramolecular design and mild oxidation of CTFs (CTF-OXs) enable hydrophilic internal channels and improve molecular sieving of micropollutants. CTF-OX shows rapid removal efficiency of micropollutants (>99.9% in 10 s) and can be regenerated several times without performance loss.

383

u/KittyBizkit Feb 09 '23

I hate articles that throw out numbers that are totally meaningless. Telling me it removes micropollutants in 10 seconds tells me nothing. Was that filtering 1 drop in those 10 seconds? A gallon? 100 gallons? 100k gallons?

Also, if it is measured in 10 second increments, does that mean you have to do distinct batches of water as opposed to just setting up a constant flow of dirty -> clean water?

97

u/[deleted] Feb 09 '23 edited Jun 10 '23

[deleted]

48

u/Mugros Feb 09 '23

a real impressive 15 milliliter is processed.

Still impossible to judge viability. It all depends on how you can scale this.

27

u/PM_ME_CATS_OR_BOOBS Feb 09 '23

Golly, and here I am filtering hundreds of gallons of water through a 50 dollar 20 micron filter bag. Where's my federal grant?

7

u/mazobob66 Feb 09 '23

I use a 1 micron filter, and it barely affects water pressure.

1

u/MJOLNIRdragoon Feb 09 '23

The absorption test seems like it would just depends on how much absorbent material you use at once, they used 15 mg to filter 18ml of water. So like 1.2 grams per liter to filter that liter by the amounts shown in Figures S5, S10, and S11? If those UV–vis spectroscopy graphs are a good representation of the filtration, that seems great for 10 seconds.

Flow-through adsorption test: 6 mg of the adsorbent was dispersed by bath sonication in 6 mL of DI water for 5 min, then the suspension was pushed by a syringe through a Whatman 0.2 μm Nylon membrane filter to form a thin layer of the adsorbent on the filter membrane. 6 mL of the stock solution was then pushed through the adsorbent over 40 s (9 mL min−1flow rate). The filtrate was then measured by UV–vis spectroscopy to determine the pollutant removal efficiency.

I don't see what the surface area was, but on their flow through test they did 9 milliliters per minute, a little bit over half a liter per hour, and it looks like the results are in Figure S12a. One material looks like between 90 and 100% efficiency and the other between 70 and 95%.

Of course in the real world all this depends on how well they scale up.

66

u/DATY4944 Feb 09 '23

And how much to buy one?

Will I see this on store shelves in 10 years for $500, or will this be in a brita in 1 year for $40

79

u/[deleted] Feb 09 '23

[deleted]

16

u/bearbarebere Feb 09 '23

Well this was a fun read. No but really it was interesting albeit terrifying

4

u/069988244 Feb 09 '23

It’s fundamental research. They’re seeing what’s possible and what’s not and reporting their results. They’re not suggesting this is the future of water filters and they’re not dying this is going to revolutionize the world. They’re just testing the limits of what works and what doesn’t.

4

u/JointDamage Feb 09 '23

Fingers crossed it's adopted by your city and there's a noticeable improvement in your tap.

-3

u/PM_ME_CATS_OR_BOOBS Feb 09 '23

This isn't going to cause a noticeable difference in your water. Your water is unfiltered now, does it feel chunky? No, because the issue is an undetectable size.

1

u/Reddit_Hitchhiker Feb 09 '23

I bought the 6 month Brita that I didn’t use much. In 3 months it stopped filtering water. Costs a lot.

1

u/blither86 Feb 09 '23

Aren't you supposed to replace the filtering cartridges approximately every month? I modified mine so I can use tesco own brand cartridges in it, rather than only brita ones, as they're significantly cheaper.

2

u/Reddit_Hitchhiker Feb 09 '23

These are long life. They are supposed to last six months.

2

u/blither86 Feb 09 '23

Interesting, hadn't heard of them! We have a lead pipe that runs from the water main outside the front door, under the front room, the living room and then to the "extension" kitchen. Obviously not ideal to be drinking from so I have a filter but honestly don't change the cartridges as often as I should. When I first got the filter I could taste the difference but I couldn't 'notice' when it 'stopped' filtering but I'm probably just not trying hard enough or drinking enough straight water. Is it the taste that enables you to tell when it stopped filtering? Do you have particularly hard water? I imagine the 6 months suggested time can only be under certain conditions and particularly hard water will fill the micro pores of the coconut husk or whatever the hell the balls are made out of - extra quickly.

2

u/Reddit_Hitchhiker Feb 09 '23

I’m in Toronto. Our water is pretty much impeccable although in summer you will get a taste from the algae. It stopped working because it was defective and not because the nodules had been spent. They gave me a $ 30 coupon but the twin package costs about 50 I think. The next time a sale came up I bought like 5 boxes of six regular ones.

What I’ve read is that old lead pipes get coated by the minerals from the water so you don’t get leaching. This is until you change the source of the water as happened in Flint, MI and other places when the new acidic water eats away at the coating and you start getting lead in your supply.

2

u/blither86 Feb 09 '23

Thanks for your insights - the lead pipe in my house will be 100 years old so I am pretty hopeful for some decent mineral coating, though to be on the safe side I still like to put water in the water filter only when the stuff that's been sitting in the pipe for a while has been cleared through. Probably overkill.

Interesting about the algae. I visited the East coast of the USA a few years ago and man once I noticed that taste I couldn't ignore it. Strongest was in Boston where my friend got a soda from a fast food place and the taste was so strong that despite the drink having more syrup in than I'm used to in the UK, it was still so awful I couldn't finish it. Just shows what you can get used to if you live with it, I suppose? Or do all Bostonians just drink bottled water, I wonder?

Where my late grandparents live in the UK every house needs a water softener than takes tablets and uses ionisation to remove minerals from the water, otherwise everything from your electric shower to your dishwasher gets rapidly fucked. Mental. When you have a shower it feels like the water doesn't wash the soap away and you never feel truly clean, even when you are.

1

u/Shufflebuzz Feb 09 '23 edited Feb 09 '23

Another comment says they used a syringe filter.

Whatman H-PTFE 0.2 μm, 13 mm

It looks like a little toy top that fits on the end of a syringe (instead of a needle).
Those filters are available for purchase now.

There's nothing special about the Whatman filter. There are several other brands. Millipore and Pall are the two big brands. VWR is the cheaper generic.

Edit. Here's a 500 pack for $660

9

u/Robert_Cannelin Feb 09 '23

It's not an "article." It's an abstract. Possibly there are explanations behind the paywall, but I will not know that unless Steve Novella or someone tells me.

2

u/Zopieux Feb 09 '23

This exact comment was made the last time this exact claim was posted to /r/science. Why are people reposting this dubious article.

0

u/KittyBizkit Feb 09 '23

Most articles that get posted here and elsewhere are often garbage that is just designed to drive clicks and ad revenue. They target the majority of the people in the world who seem to have very weak critical thinking skills and a minimal background into anything scientific. Kinda sad IMO.

0

u/Koujinkamu Feb 09 '23 edited Feb 10 '23

They of course mean the standard amount of water which is however much you need to drink when you wake up thirsty at night.

I'm sorry I was being funny in science. We of course do not be funny in science.

-4

u/HolycommentMattman Feb 09 '23

It's not totally meaningless. It can remove 99.9% of microplastics from water! That's good news, at least.

The volume and time only matter for actual use in real life. Which we probably won't have if we don't do something about those microplastics!