Evaluating the aerobic biodegradability of plastics in soil environments through GC and IR analysis of gaseous phase

• Published in: Polymer testing Vol. 26; no. 6; pp. 729 - 741
• Main Authors: Dřímal, Pavel, Hoffmann, Jaromír, Družbík, Martin
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2007; Elsevier
• Subjects: Acidimetry; Applied sciences; Biodegradation; Exact sciences and technology; Gas chromatography; IR spectroscopy; Physical properties; Polymer industry, paints, wood; Properties and testing; Soil tests; Technology of polymers; Biodegradation; Gas chromatography; Acidimetry; Soil tests; IR spectroscopy; Biological properties; Microcrystalline material; Aerobiosis; Biodegradability; Ageing; Cellulose; Carbon dioxide; Ester polymer; Xanthan gum; Butyrate(hydroxy)polymer; Experimental study; Soils; Analysis method; Aliphatic polymer; Oside polymer; Fourier-transformed infrared spectrometry
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2007.03.008

The subject of this study was the verification of various alternatives for testing the biodegradability of polymers under soil conditions. The aim was to use gas chromatography to analyse the gaseous phase (CO 2 and O 2 content), a Micro-Oxymax respirometer (IR analysis of CO 2, analysis of O 2 by paramagnetic analyser) to observe the biodegradation of polymeric substances in a soil environment in closed test flasks, and to compare measured results with a standard acidimetric procedure for determining CO 2. The experimental conditions of tests in soil were suggested as follows: test flasks of 1140 ml volume; dosage of soil inoculum: 30 g dry matter of soil and 30 g inert material (Perlite or other possessing comparable properties), soil moisture content approximately 50%, weight of test sample 150–300 mg with respect to the anticipated biodegradability. A frequency of analyses for CO 2 or O 2 content in the gaseous phase was selected so as to preserve aerobic conditions for tests (minimum 6 vol% O 2). Aeration (so-called “refresh”) was performed whenever the O 2 content in the gaseous phase of the closed flasks decreased. Under these conditions, the replacement of GC, IR and titration methods for determining CO 2 was verified in tests with a reference substrate, poly- β-hydroxybutyrate (PHB), and model samples (polysaccharide Xanthan, microcrystalline cellulose Avicel). Biodegradation was evaluated by CO 2 produced ( D CO 2 ) and O 2 consumed ( D O 2 ). Differences among values of D CO 2 were less than 5%. Differences between D CO 2 and D O 2 values (determined by GC analysis) were on a level not exceeding 10%. The selected test conditions for IR or GC determination of CO 2 and/or paramagnetic or GC determination of O 2 proved to be suitable for examining the biodegradability of substances in soils.