Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

BACKGROUND
Purification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia.

RESULTSDigestion temperatures were critical to the obtainable purity and the amount of recovered PHA. At temperatures below 75 °C (regardless of the incubation time and ammonia concentration), a low PHA recovery (down to 65 %) and no increase in purity was observed. By increasing the temperature above 75 °C, a significantly higher PHA purity and higher recovery (above 90 %) could be achieved. Temperatures maximizing the purity (140 °C) led to a detrimental reduction in the molar mass of the isolated PHA, but the use of a sonication pre‐treatment enabled to increase the purity at temperatures leading to limited molar mass loss (75‐115 °C). The impurities still present in the recovered PHA did not compromise its thermal stability, and no significant degradation occurred during melting of PHA with 86 % purity (comparably to pure chloroform‐extracted PHA). Conversely, PHA recovered through H2SO4 digestion underwent severe degradation during melting, despite presenting higher purity (98 %).

CONCLUSIONS
High PHA purity, recovery and thermal stability can be obtained with dilute ammonia digestion. These observations, combined with the possibility of reusing ammonia within the process, make this method a promising approach for a more sustainable purification of PHA.
Original languageEnglish
JournalJournal of Chemical Technology and Biotechnology
ISSN0268-2575
Publication statusAccepted/In press - 2020

Cite this

@article{b2a3478d8165469395056c3c7a6f757a,
title = "Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures",
abstract = "BACKGROUNDPurification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia.RESULTSDigestion temperatures were critical to the obtainable purity and the amount of recovered PHA. At temperatures below 75 °C (regardless of the incubation time and ammonia concentration), a low PHA recovery (down to 65 {\%}) and no increase in purity was observed. By increasing the temperature above 75 °C, a significantly higher PHA purity and higher recovery (above 90 {\%}) could be achieved. Temperatures maximizing the purity (140 °C) led to a detrimental reduction in the molar mass of the isolated PHA, but the use of a sonication pre‐treatment enabled to increase the purity at temperatures leading to limited molar mass loss (75‐115 °C). The impurities still present in the recovered PHA did not compromise its thermal stability, and no significant degradation occurred during melting of PHA with 86 {\%} purity (comparably to pure chloroform‐extracted PHA). Conversely, PHA recovered through H2SO4 digestion underwent severe degradation during melting, despite presenting higher purity (98 {\%}).CONCLUSIONSHigh PHA purity, recovery and thermal stability can be obtained with dilute ammonia digestion. These observations, combined with the possibility of reusing ammonia within the process, make this method a promising approach for a more sustainable purification of PHA.",
author = "Anna Burniol-Figols and Skiadas, {Ioannis V.} and Daugaard, {Anders E.} and Gavala, {Hariklia N.}",
year = "2020",
language = "English",
journal = "Journal of Chemical Technology and Biotechnology",
issn = "0268-2575",
publisher = "JohnWiley & Sons Ltd.",

}

TY - JOUR

T1 - Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

AU - Burniol-Figols, Anna

AU - Skiadas, Ioannis V.

AU - Daugaard, Anders E.

AU - Gavala, Hariklia N.

PY - 2020

Y1 - 2020

N2 - BACKGROUNDPurification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia.RESULTSDigestion temperatures were critical to the obtainable purity and the amount of recovered PHA. At temperatures below 75 °C (regardless of the incubation time and ammonia concentration), a low PHA recovery (down to 65 %) and no increase in purity was observed. By increasing the temperature above 75 °C, a significantly higher PHA purity and higher recovery (above 90 %) could be achieved. Temperatures maximizing the purity (140 °C) led to a detrimental reduction in the molar mass of the isolated PHA, but the use of a sonication pre‐treatment enabled to increase the purity at temperatures leading to limited molar mass loss (75‐115 °C). The impurities still present in the recovered PHA did not compromise its thermal stability, and no significant degradation occurred during melting of PHA with 86 % purity (comparably to pure chloroform‐extracted PHA). Conversely, PHA recovered through H2SO4 digestion underwent severe degradation during melting, despite presenting higher purity (98 %).CONCLUSIONSHigh PHA purity, recovery and thermal stability can be obtained with dilute ammonia digestion. These observations, combined with the possibility of reusing ammonia within the process, make this method a promising approach for a more sustainable purification of PHA.

AB - BACKGROUNDPurification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia.RESULTSDigestion temperatures were critical to the obtainable purity and the amount of recovered PHA. At temperatures below 75 °C (regardless of the incubation time and ammonia concentration), a low PHA recovery (down to 65 %) and no increase in purity was observed. By increasing the temperature above 75 °C, a significantly higher PHA purity and higher recovery (above 90 %) could be achieved. Temperatures maximizing the purity (140 °C) led to a detrimental reduction in the molar mass of the isolated PHA, but the use of a sonication pre‐treatment enabled to increase the purity at temperatures leading to limited molar mass loss (75‐115 °C). The impurities still present in the recovered PHA did not compromise its thermal stability, and no significant degradation occurred during melting of PHA with 86 % purity (comparably to pure chloroform‐extracted PHA). Conversely, PHA recovered through H2SO4 digestion underwent severe degradation during melting, despite presenting higher purity (98 %).CONCLUSIONSHigh PHA purity, recovery and thermal stability can be obtained with dilute ammonia digestion. These observations, combined with the possibility of reusing ammonia within the process, make this method a promising approach for a more sustainable purification of PHA.

M3 - Journal article

JO - Journal of Chemical Technology and Biotechnology

JF - Journal of Chemical Technology and Biotechnology

SN - 0268-2575

ER -