Degradation of conventional plastic wastes in the environment: A review on current status of knowledge and future perspectives of disposal

Ali, Sameh S.; Elsamahy, Tamer; Koutra, Eleni; Kornaros, Michael; El‐Sheekh, Mostafa M.; Abdelkarim, Esraa A.; Zhu, Daochen; Sun, Jianzhong

doi:10.1016/j.scitotenv.2020.144719

Cited by 297 publications

(151 citation statements)

References 160 publications

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“…In contrast, when sufficient oxygen cannot be maintained, polymer peroxyl radicals react with polymer macro radicals (Path 11). Conclusively, olefins and ketones are the expected products of the termination reactions [16]. The whole process causes a reduction in the molecule's weight, and the polymer becomes more brittle, leading to further photodegradation.…”

Section: Free Radical Mechanism Of Oxidationmentioning

confidence: 99%

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Photocatalytic Degradation of Plastic Waste: A Mini Review

Lee

2021

Micromachines

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Plastic waste becomes an immediate threat to our society with ever-increasing negative impacts on our environment and health by entering our food chain. Sunlight is known to be the natural energy source that degrades plastic waste at a very slow rate. Mimicking the role of sunlight, the photocatalytic degradation process could significantly accelerate the degradation rate thanks to the photocatalyst that drastically facilitates the photochemical reactions involved in the degradation process. This mini review begins with an introduction to the chemical compositions of the common plastic waste. The mechanisms of photodegradation of polymers in general were then revisited. Afterwards, a few photocatalysts were introduced with an emphasis on titanium dioxide (TiO2), which is the most frequently used photocatalyst. The roles of TiO2 photocatalyst in the photodegradation process were then elaborated, followed by the recent advances of photocatalytic degradation of various plastic waste. Lastly, our perspectives on the future research directions of photocatalytic plastic degradation are present. Herein, the importance of catalytic photodegradation is emphasized to inspire research on developing new photocatalysts and new processes for decomposition of plastic waste, and then to increase its recycling rate particularly in the current pandemic with the ever-increasing generation of plastic waste.

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Section: Free Radical Mechanism Of Oxidationmentioning

confidence: 99%

“…In the propagation step [8,16], polymer macro radicals formed through photo-initiation react with the oxygen to form polymer peroxyl radicals (Path 2). Subsequent reactions of polymer peroxyl radicals with another polymer produce hydroperoxides and polymer macro radicals (Path 3).…”

Section: Free Radical Mechanism Of Oxidationmentioning

confidence: 99%

Photocatalytic Degradation of Plastic Waste: A Mini Review

Lee

2021

Micromachines

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“…Considering the structural backbone, synthetic plastics have been broadly categorized into two groups, i.e., (1) plastics with a C-C backbone and (2) plastics with a C-O backbone (Figure 2). The first category of plastics is non-hydrolysable, and examples include polypropylene (PP) and polyethylene (PE), among others.…”

Section: Synthetic Plastics-categories and Petmentioning

confidence: 99%

“…Furthermore, the minimally reactive C-C bonds in the backbone of polyesters are considered a significant obstacle to the biodegradation process [22]. The plastic materials in the second category with a C-O backbone are hydrolysable, and examples include polyethylene terephthalate (PET) and polyurethane (PU) among others and hold around 18% of the global market share [1,23,24]. Collectively, the global plastic market was valued at around $568.9 billion in 2019, which increased to $579.7 billion in 2020, and is expected to grow at a compound annual growth rate (CAGR) of 3.4% from 2021 to 2028 [25].…”

Section: Synthetic Plastics-categories and Petmentioning

confidence: 99%

“…Plastics are synthetic materials of utmost importance in all modern societies. This is mainly because the robust attributes of plastic products evolved through time, including durability, weathering resistance, transparency, lightweight, low-price, high stability, and compact structural characteristics [1]. Undoubtedly, all these characteristics make plastics a vital entity for many domestic and industrial sectors [2].…”

Section: Introductionmentioning

confidence: 99%

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Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation

Ahmaditabatabaei

Kyazze

Iqbal

et al. 2021

JoF

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The ubiquitous persistence of plastic waste in diverse forms and different environmental matrices is one of the main challenges that modern societies are facing at present. The exponential utilization and recalcitrance of synthetic plastics, including polyethylene terephthalate (PET), results in their extensive accumulation, which is a significant threat to the ecosystem. The growing amount of plastic waste ending up in landfills and oceans is alarming due to its possible adverse effects on biota. Thus, there is an urgent need to mitigate plastic waste to tackle the environmental crisis of plastic pollution. With regards to PET, there is a plethora of literature on the transportation route, ingestion, environmental fate, amount, and the adverse ecological and human health effects. Several studies have described the deployment of various microbial enzymes with much focus on bacterial-enzyme mediated removal and remediation of PET. However, there is a lack of consolidated studies on the exploitation of fungal enzymes for PET degradation. Herein, an effort has been made to cover this literature gap by spotlighting the fungi and their unique enzymes, e.g., esterases, lipases, and cutinases. These fungal enzymes have emerged as candidates for the development of biocatalytic PET degradation processes. The first half of this review is focused on fungal biocatalysts involved in the degradation of PET. The latter half explains three main aspects: (1) catalytic mechanism of PET hydrolysis in the presence of cutinases as a model fungal enzyme, (2) limitations hindering enzymatic PET biodegradation, and (3) strategies for enhancement of enzymatic PET biodegradation.

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Recycled Additive Manufacturing Feedstocks for Fabricating High Voltage, Low‐Cost Aqueous Supercapacitors

Wuamprakhon

Crapnell

Sigley

et al. 2022

Advanced Sustainable Systems

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day life. However, managing the endof-life of plastic materials has become an increasingly urgent topic due to the reliance of most virgin plastics production on non-renewable resources like oil, and the significant, harmful effects that environmentally persistent waste plastic can have on the natural world. [1] Limiting these effects requires consumption of virgin plastic to be reduced wherever possible, and where not possible, plastic waste should be recycled into new products such that it does not enter traditional waste streams (e.g., by being sent to landfill). With regards to plastics recycling, the ideal situation is one in which innovation facilitates "upcycling" of plastic waste into products that retain high value and longevity, such that the material flow from raw material to waste product is slowed significantly. [2] Seeking upcycling in this way can be especially effective when incorporated into Circular Economy (CE) practices; [2] while the precise definition of CE has not been formalized, in broad terms, it is a new economic model intended to cause a sea change in the way society approaches sustainable development. [3] Additive Manufacturing (AM), otherwise known as 3D

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Degradation of conventional plastic wastes in the environment: A review on current status of knowledge and future perspectives of disposal

Cited by 297 publications

References 160 publications

Photocatalytic Degradation of Plastic Waste: A Mini Review

Photocatalytic Degradation of Plastic Waste: A Mini Review

Fungal Enzymes as Catalytic Tools for Polyethylene Terephthalate (PET) Degradation

Recycled Additive Manufacturing Feedstocks for Fabricating High Voltage, Low‐Cost Aqueous Supercapacitors

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