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Main Title: Recovery of the PHA Copolymer P(HB-co-HHx) With Non-halogenated Solvents: Influences on Molecular Weight and HHx-Content
Author(s): Bartels, Moritz
Gutschmann, Björn
Widmer, Torsten
Grimm, Thomas
Neubauer, Peter
Riedel, Sebastian L.
Type: Article
Abstract: Biodegradable and biocompatible polyhydroxyalkanoates (PHAs) are promising alternatives to conventional plastics. Based on the chain length of their monomers they are classified as short chain length (scl-) or medium chain length (mcl-) PHA polymers. The type of monomers, the composition and the molecular weight (MW) define the polymer properties. To accelerate the use of PHA as a bulk material, the downstream associated costs need to be minimized. This study focuses on the evaluation of non-halogenated solvents, especially acetone as a scl-PHA non-solvent, for the recovery of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) – P(HB-co-HHx) – with an mcl-HHx content >15 mol% and a MW average (Mw) < 2 × 105 Da. Solvents and precipitants were chosen regarding zeotrope formation, boiling point differences, and toxicity. Non-halogenated solvent-precipitant pairs were evaluated regarding the MW characteristics (MWCs) of the extracted polymer. Acetone and 2-propanol as a low toxic and zeotropic solvent-precipitant pair was evaluated at different extraction temperatures and multiple extraction times. The extraction process was further evaluated by using impure acetone for the extraction and implementing a multi-stage extraction process. Additionally, P(HB-co-HHx) extracted with three different solvents was characterized by 1H and 13C-APT NMR. The screening of precipitants resulted in a negative influence on the MWCs by ethanol precipitation for extractions with acetone and ethyl acetate, respectively. It was observed, that extractions with acetone at 70°C extracted a higher fraction of PHA from the cells compared to extractions at RT, but the Mw was decreased by 9% in average. Acetone with a 2-propanol fraction of up to 30% was still able to extract the polymer 95% as efficient as pure acetone. Additionally, when acetone and ethyl acetate were used in a multi-stage extraction process, a two-stage process was sufficient to extract 98–99% of the polymer from the cells. 1H and 13C-APT NMR analysis confirmed the monomer fraction and structure of the extracted polymers and revealed a random copolymer structure. The presented strategy can be further developed to an ecological and economically feasible PHA downstream process and thus contributes to the commercialization of low-cost PHAs.
Subject(s): polyhydroxyalkanoate
non-halogenated solvents
multi-stage extraction
molecular weight
medium chain length PHA
Ralstonia eutropha
Issue Date: 7-Aug-2020
Date Available: 8-Dec-2020
Language Code: en
DDC Class: 570 Biowissenschaften; Biologie
Sponsor/Funder: TU Berlin, Open-Access-Mittel – 2020
BMBF, 031B0001C, Bioökonomie International 2014: PHABIO APP - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten für die Produktion von wertschöpfendem, biobasierten und abbauendem Plastik; Teilprojekt C
BMBF, 031B0001B, Bioökonomie International 2014: PHABIO APP - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten für die Produktion von wertschöpfendem, biobasierten und abbauendem Plastik; Teilprojekt B
BMBF, 031B0798C, Bioökonomie International 2017: PHABio-up - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten: Scale-up zur Realisierung einer industriellen Produktion - Teilvorhaben: Feedstock und Produktextraktion
Journal Title: Frontiers in Bioengineering and Biotechnology
Publisher: Frontiers
Volume: 8
Article Number: 944
Publisher DOI: 10.3389/fbioe.2020.00944
EISSN: 2296-4185
TU Affiliation(s): Fak. 3 Prozesswissenschaften » Inst. Biotechnologie » FG Bioverfahrenstechnik
Appears in Collections:Technische Universität Berlin » Publications

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