Fate of So‐Called Biodegradable Polymers in Seawater and Freshwater

Abstract

The stability of polymers with C—C and stable C—heteroatom backbones against chemicals, hydrolysis, temperature, light, and microbes has challenged society with the problem of accumulation of plastic waste and its management worldwide. Given careless disposal of plastic waste, large amounts of plastic litter accumulate in the environment and disintegrate into microplastics. One of the questions frequently raised in the recent times is if so‐called biodegradable polymers can substitute conventional polymers for several applications and help to tackle this challenge. The answer is not so simple as biodegradability is a certified property occurring only under certain environmental conditions and therefore requires systematic study. As a first step, this study focusses on comparative degradation studies of six polymers (five taken from the so‐called biodegradable polyesters, including poly(lactic‐ co ‐glycolic acid) (PLGA), polycaprolactone (PCL), polylactic acid (PLA), poly(3‐hydroxybutyrate) (PHB), Ecoflex, and one well‐known non‐degradable polymer poly(ethylene terephthalate) (PET) in artificial seawater and freshwater under controlled conditions for 1 year. Only amorphous PLGA shows 100% degradation as determined by weight loss, change in molar mass with time, NMR, electron microscopy, and high‐performance liquid chromatography. This is a step forward in understanding the degradability of polyesters required for the design of environmentally friendly novel polymers for future use.

Biodegradable Polymers: Present Opportunities and Challenges in Providing a Microplastic‐Free Environment

“…A similar trend regarding the biodegradability of PLA in soil and in artificial seawater and freshwater was seen in laboratory tests. [ 10 ] Further, it is not possible to distinguish clearly in these studies between fragmentation and biodegradation. The biodegradation should be evidenced by the conversion of organic carbon to CO 2 /methane and biomass.…”

“…[ 14 ] There are no indications of the biodegradation of PBAT in aquatic systems over a period of at least 1 year. [ 10 ] Currently, the biodegradation under actual environmental conditions is only tested by following the visual change in the form, mass, structure, and properties of the polymer under test. The additional environmental factors, such as sunlight, wind, wind speed, and humidity, can have a significant influence on the rate and mechanism of polymer biodegradation under natural environmental conditions as photodegradation, photooxidation, and cross‐linking become significant in the natural environment.…”

Beyond oil degradation: enzymatic potential of Alcanivorax to degrade natural and synthetic polyesters

“…Furthermore, polymer degradation in marine environments is even more challenging due to the low temperatures and oligotrophic conditions that hamper microbial activity as well as the reduced encounter rate in such dilute ecosystems. Hence, although some marine microbial isolates have been reported to degrade a range of polyesters (Mabrouk and Sabry, ; Ghanem et al ., ; Sekiguchi et al ., ), such a process is not as obvious in marine environments as highlighted by studies that failed to observe degradation of some theoretically biodegradable polymers such as PHB, PES and PBS (Sekiguchi et al ., ; Bagheri et al ., ).…”

“…Hence, although some marine microbial isolates have been reported to degrade a range of polyesters (Mabrouk and Sabry, 2001;Ghanem et al, 2005;Sekiguchi et al, 2010), such a process is not as obvious in marine environments as highlighted by studies that failed to observe degradation of some theoretically biodegradable polymers such as PHB, PES and PBS (Sekiguchi et al, 2010;Bagheri et al, 2017).…”

Change of some characteristics of HDPE pipes tested in Nghe An province seawater

“…The results showed that PLGA was degraded completely in both 2 environments after 270 testing days while PHB was decomposed up to 8 % after 365 testing days. [2] The tensile properties of poly(3-hydroxybutyrate-cohydroxyvalerate)/polyethylene oxide ((PHBV)/PEO) modified starch blend were decreased after 150 testing days in seawater (Puerto Rico). [3] It can be seen the development of fungi on the surface of starch and blend samples.…”