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Doctoral defence of Ayobami Salami, MSc, Applied Physics, 26 Nov 2021: Biorefining of lignocellulosic biomass and chemical characterization of slow pyrolysis distillates

The doctoral dissertation in the field of Applied Physics will be examined at the Faculty of Science and Forestry on the Kuopio Campus and streamed live.

MSc Ayobami Salami, what is the topic of your doctoral research?

Biochar is a prime source of energy in most African countries and is a driving force in their economies. Biochar is one of the main products derived during the carbonization process (slow pyrolysis), and its mainly used as a low-value energy supplement for households in many African countries. In Africa, the slow pyrolysis methods used to convert wood to biochar are generating a huge amount of waste, increasing greenhouse gas emissions, increasing charcoal-induced deforestation, and the risk of environmental contamination in every year. Due to this, there is an emphasized need for the development of the bio-economy through sustainable use of wood biomass for clean energy, increase and improve the value of biomass chain using biochar process. The implementation of the European Food Safety Authority (EFSA) directives in 2009 and most importantly the EU ban on propiconazole and other active substances in plant products in 2018 suggest that synthetic pesticides pose a realistic threat to the general population. 

Currently, the agricultural sector in Europe is striving to develop natural and environmentally friendly biochars, fertilizers, and pesticides to avoid the health hazards associated with conventional synthetic pesticides. Liquid distillates obtained from slow pyrolysis potentially could resolve some of these problems. Various analytical techniques such as liquid chromatography-mass spectrometry (LC-MS), gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS), two-dimensional gas chromatography (GC × GC or 2D GC-MS), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) along with other different ionization methods. However, due to the complex nature of the distillate, it is difficult to obtain a more precise identification of the individual compounds. NMR spectroscopy is considered as the more reliable of all these analytical techniques since it potentially allows a more comprehensive and precise identification of individual compounds in LCB distillates.

 This study provides groundwork by using high-resolution 2D NMR techniques to provide a structural assignment and concentration determination of the most abundant compounds in the distillates. In addition, Thesis findings indicate an overall economic assessment of the biochar process and utilization of both water-based and bio-oil distillates, e.g. for potential natural pesticide application in the EU. 

What are the key findings or observations of your doctoral research?

 Distillates were successfully analyzed with benchtop low-resolution NMR and FT-IR. Cost-effective chemical screening of the distillates was enhanced by the complementary analyses.

 Structural assignment and determination of the concentration of most abundant compounds in industrial hemp leaves, hurds, and roots were successfully achieved with NMR, GC-MS, and FT-ICR MS. 

Complementary analytical methods were found to be suitable for detailed chemical profiling and semi-quantitative comparison of compounds in the distillates. 

The overall economic assessment of the biochar process and optimize both water-based and bio-oil distillates for potential natural pesticide production. 

How can the results of your doctoral research be utilised in practice?

 The study can be utilised in the bioeconomy development through sustainable use of wood biomass for clean energy in Africa and high-value products such as natural biopesticide and biostimulants from the biochar process.

What are the key research methods and materials used in your doctoral research?

 Thermochemical process (slow pyrolysis)

Raw materials, namely Lophira lanceolata Tiegh. ex Keay., Dialium guineense Willd, Afzelia africana Sm., and industrial hemp were pyrolyzed at temperatures RT-400 oC.  Modern slow pyrolysis equipment was used and allowed for the collection of distillates. Hotwell (HW) software and Logo software were used to control and analyse the slow pyrolysis process. Raw distillates were collected at three condensation temperatures  5 oC - 130 oC next to each other. VWR and WK1200 Lauda were used to control condensation temperatures. 

Chemical characterization

The composition of the liquid distillates was screened chemically by using cost-effective Bruker FTIR, benchtop Picospin 80 MHz 1H NMR, high-resolution 1D-2D NMR, LC-MS, GC -MS, and FT-ICR MS.

Economic assessment

The economic assessment of the overall biorefining of lignocellulosic biomass was based on our industrial hemp farm project (KUHAKO) yields.

The doctoral dissertation of MSc Ayobami Salami, entitled Biorefining of lignocellulosic biomass and chemical characterization of slow pyrolysis distillates, will be examined at the Faculty of Science and Forestry, on the Kuopio campus, on 26 November at 12 noon. The opponent will be Professor Emeritus Raimo Alén, University of Jyväskylä, and the custos will be Professor Reijo Lappalainen, University of Eastern Finland. Language of the public defence is English.

For further information, please contact:

Ayobami Salami, ayobasa (a), tel.+358 503202879

Public examination online

Dissertation book