Detection of trace metals in biogas using extractive electrospray ionization high-resolution mass spectrometry

Stamatios Giannoukos,Mohamed Tarik,Christian Ludwig,Serge Biollaz,Jay Slowik,Urs Baltensperger,Andre Stephan Henry Prevot

doi:10.1016/j.renene.2021.01.047

Stamatios Giannoukos, Mohamed Tarik + Show 5 more

Open Access

https://doi.org/10.1016/j.renene.2021.01.047

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Abstract

On-line measurements of metal emissions in energy conversion systems at very low concentrations are difficult to perform using existing techniques. Metals are of high importance due to their detrimental impact on human health, the environment and various industrial processes and/or equipment. Herewith and for the first time, we report the real-time detection and characterization of metals and trace elements in a Swiss biogas production plant using a novel technology based on an extractive electrospray ionization (EESI) source coupled to a high-resolution time-of-flight mass spectrometer (TOF-MS). The deployment examines the ability of the EESI-TOF to resolve highly transient signals, while providing a relatively straightforward and well-characterized platform for in-field diagnostic measurements. The EESI-TOF-MS was operated in the negative ion production and detection mode, and qualitative and quantitative results for a range of trace metals (e.g. Fe, Cu, Zn, Cd, Pb, etc.) were obtained. On-site results showed fast responses (1 Hz) and detection limits below 3 ng/m3. In addition, the EESI-TOF-MS was used for the off-line analysis of condensable trace metals of biogas samples collected using a continuous liquid-quench sampling system in 2-propanol. The results of the offline and online methods were compared and show good agreement.

Highlights

Biomass energy is considered as one of the renewable energy sources that meets climate change goals and contributes to the circular economy
The objectives are: a) to identify which metal elements are present in the raw biogas directly after its production from the anaerobic digestion of manure and mixed organic sources, b) to evaluate the quality of the biogas as it passes through a cleaning system, c) to determine quantitatively the main metals present along the entire production and processing line and d) to compare on-line analysis with off-line measurements of raw biogas samples collected by a continuous liquid-quench sampling (LQS) system
Sampled metal particles interact with the highly charged reagent analyte spray droplets and bind strongly among them, generating complexes of the general form: [Ethylenediaminetetraacetic acid (EDTA) þ XM e yH], where x is the atomic mass of the metal isotope and y the number of hydrogen cations lost during the deprotonation, which depends on the oxidation state in which the detected metal exists [25]

Summary

Introduction

Biomass energy is considered as one of the renewable energy sources that meets climate change goals and contributes to the circular economy. It refers to the conversion of biogenic waste such as agricultural, industrial and domestic waste into solid, liquid and biogas fuel. Bioenergy conversion processes include thermal (i.e., combustion, torrefaction, pyrolysis, gasification), biochemical (i.e. anaerobic digestion, fermentation, composting) and electrochemical procedures. One of the most common biogas production techniques is anaerobic digestion, during which specific groups of microorganisms promote a sequence of chemical processes and decompose biodegradable organic material (e.g. sewage, municipal waste, agricultural waste, manure, and food waste). Raw biogas is a complex mixture of output gases, primarily consisting of methane (50e75%), carbon dioxide (20e45%) and traces of other gases such as nitrogen, oxygen and hydrogen as well as volatile organic compounds, hydrocarbons, organohalogens, organosulfur compounds, or siloxanes [1e4]

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