81–90 of 141 posts
Earlier quoted context omitted.
It needs gold and platinum catalyst. The trouble would be there would be no catalyst in the plant to process water, the day after it is deployed in a remote area.
*palladium Though I guess that is also a precious metal.
> A typical H₂O₂ synthesis reaction was carried out using 120 mg of 1% AuPd/TiO₂ [...] The reactor system was then pressurized, typically to 10 bar. The reactor was then cooled by a water bath to 2 °C. When the reactor had reached the required pressure and the flow through the system had stabilized, the solvent (H²O, HPLC grade), typically at a flow of 0.2 ml min¯¹, was introduced into the system.
Oh hey, 0.2 mL/min of water. In Virginia, the lowest flow cutoff for waterworks is 0.5 MGD (or 5000 people), the border between Class 3 and Class 4. That flow rate is 6.5 million times that done in the tests here. The large water treatment plant I worked at is another 400 times that, and there are plants that would be another 5 or 6 times that. So the necessary scaling factor is going to be measured in the billions.
So what about those reagants? This uses about 0.6 mg of gold to process 0.2 mL/min of water (if I'm reading the notation of 1% AuPd/TiO₂ correctly). Scale that to our small plant, and that's about $225,000 of gold and $350,000 of palladium. Go to the scale I worked at, and that's $190 million of catalyst in terms of raw metal worth alone. That's comparable to the cost of a regular treatment plant of that scale--just on the catalyst. This assumes that there's a neat linear scaling, which I doubt is going to be the case (square-cube law!).
Earlier quoted context omitted.
Part of what will prevent mass adoption is it ignores distribution, which will still require chemical residual treatment, like chlorination. If you have to install chlorinating equipment and operate it, then it becomes a matter of if the marginal savings in chlorine is worth it. However there's also a good chance that chlorine concentration is controlled by downstream factors more than initial treatment- which is bas…
I'm not very familiar with this field, why is chlorination required in addition to peroxide? Is it because it's pretty stable and so provides protection after the water has left the treatment plant? If that's the case, I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between pro…
Yes, that is what residual treatment is.
I'm not familiar with peroxide systems, but for this industry, you don't change things without a very good reason. If we're talking about new niche uses, then that's a different story, but still merits caution.
Related story:
Washington DC tried to "upgrade" from a chlorine system to another chlorine derivative that was supposed to have some marginal EPA benefits, and on paper it was a great design.
In practice (and many tens/hundreds of millions of dollars later), the water quality had a sharp decline, with all sorts of unexpected chemicals showing up. It turns out the old system had the unintentional side effect of "filtering" out all kinds of nasty reactive stuff (including lead), and the new chemical balance reversed the process. All the chemicals that had been sequestered in the pipe walls for decades or longer, were now getting pulled back into the water. Oops.
Then there was the initiative in India where thousands of water wells were drilled, only to discover the water contained arsenic.
>I suspect that the type of decentralized system the authors think that this is useful for would be a nature where that's less of a concern. Smaller system leading to decreased time/distance between processing and use.
It may, but UV disinfection has similar properties and has been available for a while now, probably at a lower price.
Also, if water's getting transported in personal containers, chances are they're dirtier than any water main. It's easy to draw the limits of the system at a convenient point, but these are the situations that probably need residual treatment more than than we do.
Of course reality dictates what's feasible, especially in the 3rd world, and "exciting" new tech like this might get funding that boring old school solutions won't.
Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better...and makes me suspicious of any claim in the article. Hopefully it can help people in areas that are currently without clean water, but I'm not holding my breath.
If you take your 90%+ as a baseline (ie zero) then you can fiddle with the stats to get a massive number. Let's say the best effort is 91.001% and our smart new process is 92.001%. Now set the baseline at 91.000% This is the sleight of hand bit: If we say that "normal" is 91.000, we now set the best effort as 0.001 and our effort as 1.001. That can seem quite reasonable when trotted out by a news reader or reporter.…
But in your example it's more sane if you flip it.
Survival rate from a new medicine may be 99.99% and only allows 1.0001 multiple of improvement. For severe outcomes, not allowing expansive language to describe improvements is a legitimate problem. i.e. if we insisted on this, it would be hard to motivate improvements in safety from 99% to 99.999% since they are "only So in cases like this I think of it in reverse: the death rate of 0.01% can be improved by 90% (or 10x) to 0.001%. This does run the risk of inflating the importance of the fix when the base rate is extremely low.
My rule is: articles which use multiples or percentages must give enough detail to exactly reconstruct the calculation method used.
Yeah, the use of "millions of times better" just doesn't pass the sniff test. Given that current commercial methods kill 90%+ bacteria in water, thus, nothing can be even 2x better...and makes me suspicious of any claim in the article. Hopefully it can help people in areas that are currently without clean water, but I'm not holding my breath.
If you take your 90%+ as a baseline (ie zero) then you can fiddle with the stats to get a massive number. Let's say the best effort is 91.001% and our smart new process is 92.001%. Now set the baseline at 91.000% This is the sleight of hand bit: If we say that "normal" is 91.000, we now set the best effort as 0.001 and our effort as 1.001. That can seem quite reasonable when trotted out by a news reader or reporter.…
The real problem is percentages; people also intuitively assume "50% less than (50% more than X) is X"
"heres a solution for limitless free energy! step one, launch a bunch of solar reflectors into space to reflect solar energy at concentrated points on the surface of the earth. Step 2, wait, you don't have a scalable and advanced aerospace industry capable of launching thousands of collectors into orbit? I guess this won't work for you."
Earlier quoted context omitted.
The researcher himself is directly quoted saying things like “revolutionising water disinfection technologies around the world”. If that’s not backed up by it being feasible or valuable commercially, then the criticism is spot on.
I think the point is the science can be useful in that endeavor by demonstrating a new approach one can take. That’s not to say it’s all that would be required. It’s unreasonable and incorrect to expect a full commercial solution to come directly out of a set of lab experiments.
Oh dear. After reading the notes in the study itself about the scale this was done at, scaling up might be an issue: > A typical H₂O₂ synthesis reaction was carried out using 120 mg of 1% AuPd/TiO₂ [...] The reactor system was then pressurized, typically to 10 bar. The reactor was then cooled by a water bath to 2 °C. When the reactor had reached the required pressure and the flow through the system had stabilized, th…
Now others can try to reproduce it, refine it, find other methods of producing the same reactive oxygen species, find substitutes that are more effective or cheaper, etc.
It doesn't have to be panacea either. Maybe it will fill a niche. It could save some lives.