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Post by David B. Benson on Apr 5, 2019 7:08:39 GMT 9.5
Plastic pollution costs the world up to $ 2.5bn a year, researchers find Kate Hodal 2019 Apr 04 The Guardian
Effects on the climate? Unknown what the microplastics will do.
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Post by huon on Apr 6, 2019 14:00:53 GMT 9.5
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Post by Roger Clifton on Apr 7, 2019 12:55:06 GMT 9.5
I read an article recently that said that a survey showed that the plastic sitting on the ocean floor is only about a quarter of the plastic that went into the ocean. The article indicated that it may be good news, implying that the stuff is being mopped up somehow on the way down. It could be being dissolved, oxidised or digested.
Whereas dissolution would be largely a function of the surface area, oxidation would vary according to the chemistry of the polymer, and digestion would vary with its toxicity. So I guess a analysis of what plastic reached the ocean floor, or more exactly, what failed to reach the ocean floor, would tell us something about where it went.
There is another possibility – that it is being eaten, broken up and expelled undigested. That would mean that the stuff is remaining in suspension in the oceans, cycling endlessly through scavengers' diets. But at least its surface area would have been increased in the process, and its other modes of decay accelerated.
On land, termites have been known to munch their way through PVC insulation. In this case, they are not after the vinyl chloride monomer, but after the plasticiser, typically phthalate. Plasticiser use has changed over the years, as presses and extruders have become more powerful, but they are still used in different forms in different plastics – and in different products.
A smooth surface would present little opportunity for a microbe or crustacean to eat into, breaking up the object. That presupposes that the bug can digest it, as one might expect of polythene and other CH or CHO polymers. Or just the plasticiser in the case of certain termites. There is a lurking hazard that the biosphere will evolve a widespread means of breaking down the vinyl chloride monomer. In the first instance that would mean widespread collapse of electrical installation and greywater piping, in the environments favouring the bug concerned. Further, the possibility that they will excrete the relatively indigestible C-Cl bond into the atmosphere presents a direct threat (as Freon did) to the ozone layer.
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Post by David B. Benson on Apr 7, 2019 13:20:46 GMT 9.5
The Chemistry of Plastic Marine Debris 6th International Marine Debris Conference 2018 Mar 12--16
Plastics do degrade, releasing additives considered harmful.
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Post by Roger Clifton on Apr 8, 2019 2:55:12 GMT 9.5
The Chemistry of Plastic Marine Debris 6th International Marine Debris Conference 2018 Mar 12--16 Hi David. I was able to find the conference, but not the page you were looking at. Would you provide us with enough keywords to go straight to the webpage, please?
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Post by David B. Benson on Apr 8, 2019 8:38:20 GMT 9.5
The Chemistry of Plastic Marine Debris
finds the page of abstracts for me. There is not a separate link per presented paper.
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Post by Roger Clifton on Apr 8, 2019 10:40:11 GMT 9.5
Got it. Your link connects me to the abstracts, dense with information...
The most common plastic, polythene (or more correctly, "polyethylene") ages with time by a crystallisation process that must open up cracks into the interior, because the outgassing of short chains (methane, ethene, ethane) increases with the ageing. Polypropylene chains also leach out, suggesting that colloidal dissolution may be significant decay pathway for all immersed plastics. Skin weathering is due primarily to exposure to sunlight, countered partially by UV blockers lingering in the artefact. So yes, plastics do decay. Eventually.
Colloidal dissolution may well be the process that keeps soils clean of charcoal in forested areas that are frequently burned over. Similarly, it casts a time limit on how long "soil sequestration" schemes can keep biochar buried.
Crystallisation to denser forms is aided by pressure, so would be expected to be faster at depth.
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Post by David B. Benson on Apr 13, 2019 18:27:37 GMT 9.5
Researchers characterize molecular scissors for plastic waste 2019 Apr 12 Phys.org
PET plastic is broken by PETase and MHETase, but not efficiently. These were found in bacteria.
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Post by huon on Apr 14, 2019 14:11:24 GMT 9.5
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Post by David B. Benson on Apr 16, 2019 14:16:19 GMT 9.5
Airborne plastic particles blanket remote mountains: study Marlowe Hood 2019 Apr 15 Phys.org
Remote Pyrenees Mountains as badly off as greater Paris.
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Post by David B. Benson on Apr 16, 2019 14:37:09 GMT 9.5
Researchers conduct the first global assessment of the life cycle greenhouse gas emissions from plastics Harrison Tasoff 2019 Apr 15 Phys.org
"All told, the emissions from plastics in 2015 were the equivalent of nearly 1.8 billion metric tons of CO2."
"Currently, 90.5% of plastic goes un-recycled worldwide, ..."
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Post by Roger Clifton on Apr 17, 2019 10:05:23 GMT 9.5
It says... "bio-based plastics could also drive down emissions. ... the material itself carbon-neutral, although manufacturing still generates a small amount of greenhouse gasses (sic).... Ultimately, Suh and Zheng found that replacing fossil-based energy with renewable sources had the greatest impact on plastic's greenhouse gas emissions overall. Transitioning to 100% renewable energy — a purely theoretical scenario, Suh concedes — would reduce emissions by 51%""Ultimately 51%"? I would have thought that the word "ultimately" should lead us to an ultimate scenario, where 100% noncarbon energy is used to manufacture goods from 100% bio-plastic. But he did not say "noncarbon", he said "renewable", which inevitably ends up being backed by carbon-based gas. It would seem that the author is surrounded by an audience that will not tolerate anything less than 50% carbon-based fuel, dooming us to 50% emissions. However, are they all really so intolerant of researchers saying otherwise?
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Post by David B. Benson on Apr 18, 2019 15:41:55 GMT 9.5
What's happened to all the plastic rubbish in the Indian Ocean? 2019 Apr 17 Phys.org
There doesn't seem to be a so-called garbage patch in the Bay of Bengal. The Southern Indian Ocean is blown over to the South Atlantic Ocean, where there is a small gyre. The authors from University of Western Australia are left with a mystery.
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Post by David B. Benson on Apr 19, 2019 16:30:41 GMT 9.5
The Toxic Consequences of America's Plastics Boom Zoe Carpenter 2019 Mar 14 The Nation, 2019 Apr 01 issue
Available online.
Thanks to fracking, petrochemicals giants are about to make the plastic pollution crisis much, much worse.
This is a result of ethane being essentially free. I'm still reading the article in the print edition.
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Post by engineerpoet on Apr 20, 2019 0:40:43 GMT 9.5
Researchers invent pathway to make gasoline-range cyclic hydrocarbons and aromatics from PET waste: www.greencarcongress.com/2019/04/20190415-dalian.htmlThe first step in this process regenerates dimethylterephthalate monomer by reaction of PET with methanol. The regenerated DMT precipitates out when the temperature is lowered. I did a bit of digging and found that PET is made by reacting DMT with ethylene glycol, producing MeOH as a byproduct. It appears that this could allow complete recycling of PET, not just conversion into fuels.
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Post by David B. Benson on Apr 20, 2019 8:43:40 GMT 9.5
Seabin --- 'rubbish bin for the water' --- comes to Australia Kerrin Thomas 2019 Apr 20 ABC, Australia
Typically installed in marinas, etc. Gets some of the floating plastic.
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Post by Roger Clifton on Apr 21, 2019 13:49:40 GMT 9.5
...this could allow complete recycling of PET, not just conversion into fuels. Before this or that plastic can be recycled, it must be sorted from the municipal waste stream. Currently the sorting is done almost entirely by human hand, with a necessary collapse of efficiency, limiting recycling to only the most valuable plastic/glass/etc. However this might be one of the most useful applications of AI (artificial intelligence). If the waste stream is crushed, then a series of sensors might supply the characterising information to the AI, so that it may choose which side stream each fragment should go. Thus the different plastics and other materials might form a reliable source of raw materials for recycling.
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Post by engineerpoet on Apr 21, 2019 22:58:19 GMT 9.5
Before this or that plastic can be recycled, it must be sorted from the municipal waste stream. In regions with bottle laws, much of this is already done for PET. The Tomra and other machines accept bottles, crush them and put them into bins. What you get is a pre-sorted supply of slightly dirty PET, plus whatever the labels and bottle caps are made of (HDPE and/or PP for the caps, from what I dug up). It seems likely to me that the methanol reaction also yields ethylene glycol. It looks like the initial reaction would be MeOH + PET bottles in, MeOH + DMT + glycol solution plus other solids out. HDPE and PP appear to be immune to methanol and will separate by filtration. The HDPE/PP can be recycled separately, the DMT precipitates when the temperature is lowered, and the MeOH and glycol separate from residual soda by distillation. Hmmm... residual soda is sugary. If you can strip the MeOH well enough to avoid inhibiting yeast you might have a product suitable for fermentation. Voila, a fuel stream (albeit a very small one).
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Post by Roger Clifton on Apr 23, 2019 8:43:18 GMT 9.5
What's happened to all the plastic rubbish in the Indian Ocean? There is no doubt that flotsam is routinely blown south-west clean across the span of the Indian Ocean. Wreckage from the missing Malaysia Airlines flight MH 370 that crashed off Australia has been found in several places across the southern African coast and islands on the way. (1) The same strong tradewinds drive the Agulhas current (2) close along that coast and past the Cape, where its momentum (not IMHO wind) carries it a short distance into the Atlantic. It is undercut by the colder and denser eastbound Antarctic Circumpolar Current (3). The latter is the world's strongest current, its eastward momentum drawing water up from the entire ocean column and the Ekman force (a Coriolis effect referred to in the paper (4)) driving a near-surface flow northwards into each of the three great ocean basins. At a conference I heard that if the Current were magically stopped, it would take 400 years to rebuild its momentum. The Current is maintained by the relentless winds of the Roaring Forties and Fifties, raising a sea that I imagine would fragment and sink any plastics entering it. The paper is behind a pay wall, but its abstract is accessible (4). I'm particularly interested to hear of research from The University of Western Australia as it has given me two degrees. Similarly the nearby Curtin University, which also has a strong oceanographic section. Both focus on the Indian Ocean, including the search for the MH 370. (1) www.theguardian.com/world/ng-interactive/2017/jan/17/missing-flight-mh370-a-visual-guide-to-the-parts-and-debris-found-so-far(2) en.wikipedia.org/wiki/Agulhas_Current(3) en.wikipedia.org/wiki/Antarctic_Circumpolar_Current(4) agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JC014806
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Post by David B. Benson on Apr 24, 2019 14:20:27 GMT 9.5
Hello, Little Microbe. Doesn't This Jacket Look Yummy? Vanessa Friedman 2019 Apr 22
The New York Times
Attempts to make fiberfill jackets which degrade relatively swiftly after use. A long slog ahead, in my humble opinion.
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Post by David B. Benson on Apr 30, 2019 16:02:39 GMT 9.5
Chemists make thermoset polymer using amine and triketone that is recyclable Bob Yirke 2019 Apr 29 Phys.org
The recycling requires acid. Unsure how feasible this is.
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Post by engineerpoet on May 1, 2019 1:35:21 GMT 9.5
Here's the article link: phys.org/news/2019-04-chemists-thermoset-polymer-amine-triketone.htmlStrong acids are widely used in industrial chemistry. Concentrated H2SO4 travels well by railroad tank car. HNO3, HCl and HF find uses all over the place. I find the diagram in the article a bit unclear but it looks like the acid is a proton donor which reverses the polymerization reaction by turning the amine group into ammonium. It's likely that the acid can be regenerated and recycled once the ammonium salts are separated. If the application of the plastic does not require acid resistance, it looks like this could be the thermosetting resin counterpart to the methanolysis recycling of PET.
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Post by David B. Benson on May 10, 2019 17:08:12 GMT 9.5
Researchers develop viable, environmentally-friendly alternative to Styrofoam Tina Hilding 2019 May 09 Phys.org
This may well replace many of the uses of Styrofoam. The major constituent is a forestry industry waste product which the wood processers burn to be rid of.
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Post by David B. Benson on May 14, 2019 9:16:04 GMT 9.5
Mismanaged waste 'kills up to a million people a year globally' Fiona Harvey 2019 May 13 The Guardian
Plastics make the problem worse.
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Post by David B. Benson on May 15, 2019 13:49:09 GMT 9.5
It's not just fish, plastic pollution harms the bacteria that help us breathe 2019 May 14 Phys.org
Prochlorococcus is the most abundant photosynthetic organism in the oceans. Laboratory tests demonstrate that chemicals "leached" from common plastics are detrimental.
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Post by David B. Benson on May 17, 2019 10:50:59 GMT 9.5
Some of the plastic in the Indian Ocean ends up on Cocos Island:
414 million pieces of plastic found on remote island group in the Indian Ocean Ben See 2019 May 16 The Guardian
I wonder whether this is another application in oceanography of the Brouwer Fixed Point Theorem as is Sable Island in the North Atlantic Ocean.
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Post by Roger Clifton on May 17, 2019 12:28:58 GMT 9.5
The Great Ocean Conveyor Belt is a flow of surface water that en route, passes from the North Pacific Ocean, through Indonesia, into the northern Indian Ocean. Close to the equator, the trade winds then blows some of it eastward. Consequently, one would expect that Cocos and Keeling Islands (south-west of Sumatra) would collect plenty of North Pacific flotsam.
Much of the flow through Indonesia passes through the Lombok Strait. Forty-odd years ago I visited the beach at Lombok Strait, more or less to pray at the Wallace Line. The beach had collected hulks of palm tree trunks, many coconuts in various stages of sprouting and dying, and the broken timber that was thrown off cargo ships in those days. About five years ago I visited the same beach for the same reason. However, this time it was littered with human jetsam, mainly plastic bottles with their lid still on, labelled in Japanese, Korean, Chinese, Bahasa, Thai, Tagalog and English. But no Hindi.
I would bet that the plastic found on Cocos Island originates from the North Pacific rather than the Indian Ocean rim.
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Post by David B. Benson on May 17, 2019 17:50:05 GMT 9.5
Quickly checking the surface currents of the ocean off West Australia it does appear that Cocos Island is near the locus of a small counter-clockwise gyre.
Indeed, the current on the north side is from Indonesia. I would suspect much of the plastic from there.
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Post by David B. Benson on May 17, 2019 19:03:05 GMT 9.5
East Timor on the forefront of fixing the global recycling crisis James Massola 2019 May 17 Sydney Morning Herald
They want to build a plastic recycling plant. We shall see...
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Post by David B. Benson on May 18, 2019 11:17:53 GMT 9.5
Plastics are sealing the planet's fate Sarah Sax 2019 May 19 ThinkProgress
Currently the equivalent to 200 coal burning power plants according to this article which offers a fine review.
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