Analytical methodology for sampling and analysing eight siloxanes and trimethylsilanol in biogas from different wastewater treatment plants in Europe.
Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200 L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0 mg Nm(-3), respectively, and exceeding the tolerance limit of most energy conversion systems.
CETaqua, Centro Tecnológico del Agua, Carretera d'Esplugues 75, 08940 Cornellà de Llobregat, Spain. Electronic address: jordiraich@gmail.com.
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Raich-Montiu
Dpto Química Analítica, Sección de Cromatografía, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain.
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Ribas-Font
CETaqua, Centro Tecnológico del Agua, Carretera d'Esplugues 75, 08940 Cornellà de Llobregat, Spain.
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de Arespacochaga
Dpto Química Analítica, Sección de Cromatografía, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain.
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Roig-Torres
Dpto Química Analítica, Sección de Cromatografía, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain.
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Broto-Puig
CIRSEE, Suez-Environnement, 38 rue du Président Wilson, F-78230 Le Pecq, France.
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Crest
CETaqua, Centro Tecnológico del Agua, Carretera d'Esplugues 75, 08940 Cornellà de Llobregat, Spain.
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L
Bouchy
CETaqua, Centro Tecnológico del Agua, Carretera d'Esplugues 75, 08940 Cornellà de Llobregat, Spain.
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JL
Cortina
D005060:Europe; D008401:Gas Chromatography-Mass Spectrometry; D005740:Gases; D057230:Limit of Detection; D012833:Siloxanes / Q000032:analysis*; D014297:Trimethylsilyl Compounds / Q000032:analysis*; D062065:Wastewater; D018508:Water Purification / Q000295:instrumentation*
D005740:Gases; D012833:Siloxanes; D014297:Trimethylsilyl Compounds; D062065:Wastewater; C055926:trimethylsilanol
Biogas; Gas chromatography coupled to mass spectrometry; Sampling techniques; Siloxanes; Trimethylsilanol; Waste water treatment plants