Editing Polystyrene (section)

==Degradation==
Polystyrene is relatively chemically inert. While it is waterproof and resistant to breakdown by many acids and bases, it is easily attacked by many organic solvents (e.g. it dissolves quickly when exposed to [[acetone]]), chlorinated solvents, and aromatic hydrocarbon solvents. Because of its resilience and inertness, it is used for fabricating many objects of commerce. Like other organic compounds, polystyrene burns to give [[carbon dioxide]] and [[water|water vapor]], in addition to other thermal degradation by-products. Polystyrene, being an [[aromatic hydrocarbon]], typically [[Charring|combusts incompletely]] as indicated by the [[soot]]y flame.{{Citation needed|date=January 2021}}

The process of [[Depolymerization|depolymerizing]] polystyrene into its [[monomer]], [[styrene]], is called [[pyrolysis]]. This involves using high heat and pressure to break down the chemical bonds between each styrene compound. Pyrolysis usually goes up to 430&nbsp;°C.<ref>{{Cite web |url=https://www.azocleantech.com/article.aspx?ArticleID=336 |title=What is Pyrolysis? |date=2012-12-29 |website=AZoCleantech.com |language=en |access-date=2019-08-15}}</ref> The high energy cost of doing this has made commercial recycling of polystyrene back into styrene monomer difficult.{{Citation needed|date=January 2021}}

===Organisms===
Polystyrene is generally considered to be non-biodegradable. However, certain organisms are able to degrade it, albeit very slowly.<ref>{{cite journal |last1=Ho |first1=Ba Thanh |last2=Roberts |first2=Timothy K. |last3=Lucas |first3=Steven |title=An overview on biodegradation of polystyrene and modified polystyrene: the microbial approach |journal=Critical Reviews in Biotechnology |date=August 2017 |volume=38 |issue=2 |pages=308–320 |doi=10.1080/07388551.2017.1355293|pmid=28764575 |s2cid=13417812 }}</ref>

In 2015, researchers discovered that [[mealworm]]s, the larvae form of the darkling beetle ''Tenebrio molitor'', could digest and subsist healthily on a diet of EPS.<ref name="news.stanford.edu">{{cite web |title=Plastic-eating worms may offer solution to mounting waste, Stanford researchers discover |author=Jordan, R. |date=29 September 2015 |url=http://news.stanford.edu/pr/2015/pr-worms-digest-plastics-092915.html |website=Stanford News Service |publisher=Stanford University |access-date=4 January 2017 |archive-date=8 January 2021 |archive-url=https://web.archive.org/web/20210108134659/https://news.stanford.edu/pr/2015/pr-worms-digest-plastics-092915.html |url-status=dead }}</ref><ref name="mealworms">{{cite journal |vauthors = Yang Y, Yang J, Wu WM, Zhao J, Song Y, Gao L, Yang R, Jiang L |title = Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests |journal = Environmental Science & Technology |volume = 49 |issue = 20 |pages = 12080–6 |date = October 2015 |pmid = 26390034 |doi = 10.1021/acs.est.5b02661 |bibcode = 2015EnST...4912080Y }}</ref> About 100 mealworms could consume between 34 and 39 milligrams of this white foam in a day. The droppings of mealworm were found to be safe for use as soil for crops.<ref name="news.stanford.edu"/>

In 2016, it was also reported that superworms (''[[Zophobas morio]]'') may eat expanded polystyrene (EPS).<ref>{{cite web |title=Think you can't compost styrofoam? Mealworms are the answer! |url=http://livingearthsystems.com/mealworms-compost-styrofoam/ |publisher=Living Earth Systems |website=Blog |date= 2016-10-08|access-date=4 January 2017}}</ref> A group of high school students in [[Ateneo de Manila University]] found that compared to ''Tenebrio molitor'' larvae, ''Zophobas morio'' larvae may consume greater amounts of EPS over longer periods of time.<ref>{{cite web |last1=Aumentado |first1=Dominic |title=A Comparative Study of the Efficacy of ''Tenebrio molitor'' Larvae and ''Zophobas morio'' Larvae as Degradation Agents of Expanded Polystyrene Foam |website=Academia |url=https://www.academia.edu/43122081}}{{primary source inline|date=September 2020}}</ref>

In 2022 scientists identified several bacterial genera, including ''[[Pseudomonas]]'', ''[[Rhodococcus]]'' and ''[[Corynebacterium]]'',  in the gut of superworms that contain encoded enzymes associated with the degradation of polystyrene and the breakdown product styrene.<ref name="Sun et al. 2022">{{cite journal |last1=Sun |first1=Jiarui |last2=Prabhu |first2=Apoorva |last3=Aroney |first3=Samuel T. N. |last4=Christian |first4=Rinke |title=Insights into plastic biodegradation: community composition and functional capabilities of the superworm (Zophobas morio) microbiome in styrofoam feeding trials |journal=Microbial Genomics |date=2022 |volume=8 |issue=6 |pages=1–19 |doi=10.1099/mgen.0.000842 |doi-access=free |pmid=35678705 |pmc=9455710 }}</ref>

The bacterium ''[[Pseudomonas putida]]'' is capable of converting [[styrene]] oil into the [[biodegradable plastic]] [[Polyhydroxyalkanoates|PHA]].<ref>{{cite web |last=Roy |first=Robert |url=http://www.livescience.com/technology/060307_styrofoam_cup.html |title=Immortal Polystyrene Foam Meets its Enemy |publisher=LiveScience |date=2006-03-07 |access-date=2019-01-17}}</ref><ref>{{cite journal |vauthors = Ward PG, Goff M, Donner M, Kaminsky W, O'Connor KE |title = A two step chemo-biotechnological conversion of polystyrene to a biodegradable thermoplastic |journal = Environmental Science & Technology |volume = 40 |issue = 7 |pages = 2433–7 |date = April 2006 | pmid = 16649270 |doi = 10.1021/es0517668 |bibcode = 2006EnST...40.2433W }}</ref><ref>{{cite journal |last1=Biello |first1=David |title=Bacteria Turn Styrofoam into Biodegradable Plastic |journal=Scientific American |date=27 February 2006 |url=http://www.scientificamerican.com/article/bacteria-turn-styrofoam-i/}}</ref> This may someday be of use in the effective disposing of polystyrene foam. It is worthy to note the polystyrene must undergo pyrolysis to turn into styrene oil.{{Citation needed|date=January 2021}}