Efficient Lignin Fractionation from Scots Pine (Pinus sylvestris) Using Ammonium-Based Protic Ionic Liquid : Process Optimization and Characterization of Recovered Lignin

Lignin-based chemicals and biomaterials will be feasible alternatives to their fossil-fuelbased counterparts once their breakdown into constituents is economically viable. The existing commercial market for lignin remains limited due to its complex heterogenous structure and lack of extraction/depolymerization techniques. Hence, in the present study, a novel low-cost ammoniumbased protic ionic liquid (PIL), 2-hydroxyethyl ammonium lactate [N11H(2OH)][LAC], is used for the selective fractionation and improved extraction of lignin from Scots pine (Pinus sylvestris) softwood biomass (PWB). The optimization of three process parameters, viz., the incubation time, temperature, and biomass:PIL (BM:PIL) ratio, was performed to determine the best pretreatment conditions for lignin extraction. Under the optimal pretreatment conditions (180 ◦C, 3 h, and 1:3 BM:PIL ratio), [N11H(2OH)][LAC] yielded 61% delignification with a lignin recovery of 56%; the cellulose content of the recovered pulp was approximately 45%. Further, the biochemical composition of the recovered lignin and pulp was determined and the recovered lignin was characterized using 1H–13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, quantitative 31P NMR, gel permeation chromatography (GPC), attenuated total reflectance (ATF)–Fourier transform infrared spectroscopy (ATR-FTIR), and thermal gravimetric analysis (TGA) analysis. Our results reveal that [N11H(2OH)][LAC] is significantly involved in the cleavage of predominant β–O–4’ linkages for the generation of aromatic monomers followed by the in situ depolymerization of PWB lignin. The simultaneous extraction and depolymerization of PWB lignin favors the utilization of recalcitrant pine biomass as feedstock for biorefinery schemes

Remote energy lab. Experience and improvements of european cooperation in remote labs

Due to the COVID-19 pandemic, online teaching methods have gained more interest. Most formats of teaching can be easily transferred into an online format from a technical point of view. However, this is more difficult for practical courses in a laboratory. Together with partners from three European universities, we tackled the issue of providing a practical online course for higher education levels in the framework of the EuroTeQ university. In this work, we present our concept of the course and discuss the course goals and further improvements. We tested the remote lab setting in order to offer the course on a yearly basis in future. The remote lab was focused on energy engineering and was open to students from different engineering disciplines and countries. The course was comprised of three blocks, each consisting of one lecture on the broader context of the topic and one experimental laboratory session. The experimental session was streamed via a video broadcasting service. Students were required to either deliver a written report or to write a newspaper article for each of the three blocks. The learning outcome of the course was that students on the one hand learn about the technologies discussed in the course and on the other hand learn about intercultural communication skills. The goal was to show the diversity of technologies and to show the significance of each technology for a specific country. The online experimental sessions proved to deliver a clear explanation of the topic for the students when provided with sufficient course material adapted to online formats. Contrary, keeping a high level of interaction with students during remote experiments was found most challenging

Characterization of oil shale kerogen semi-coke and its application to remove chemical pollutants from aqueous solutions

An alternative adsorbent from oil shale semi-coke material for removing chemical pollutants from aqueous solutions was investigated. For this purpose, enriched oil shales with different kerogen contents (57, 79 and 90 wt%) were pyrolyzed in nitrogen atmosphere at 600â900 °C at a heating rate of 10 °C/min and a hold time of 60 min. The surface properties of semi-cokes, namely Brunauer-Emmett-Teller (BET) surface area, pore volume and pore size distribution (PSD), were determined by nitrogen adsorption. The studied semi-cokes were found to be micro- and mesoporous. The highest semi-coke BET surface area, 160 m2/g, was obtained at a pyrolysis temperature of 700 °C, which corresponds to 519 m2/g of char, excluding the minerals. This porous carbon material was tested as an adsorbent to remove pesticides and phenolic compounds from aqueous solutions. Three kinds of phenolic compounds (resorcinol, 5-methylresorcinol, 4-nitrophenol) and three kinds of organophosphorus pesticides (dimethoate, parathion, malathion) were tested to study the adsorption on the semi-coke material. Different contact times were tested for the adsorption of the compounds of interest. The results showed that with an adsorbent dosage of 10 mg/mL over 98% of pesticides were removed from the solution within 30 min at an initial concentration of 100 µM (corresponding to 23â33 mg/L depending on the compound). More than 97% of the phenolic compounds were adsorbed from water within six hours at an initial concentration of 10 µM (1.1â1.4 mg/L)

Long-term mineral transformation of Ca-rich oil shale ash waste

Power generation and other industries using solid fossil fuels like coal, lignite, oil shale and peat are responsible for producing large quantities of solid residues that are often chemically reactive and/or unstable and are disposed in holding ponds and deposition sites. Stability and long-term behaviour of such deposits are typically studied in short-term laboratory experiments that cannot describe nor predict long-term changes taking place in these materials. Here, we study long-term (>40 years) transformations, in highly alkaline conditions, of the Ca-rich ash deposit in Estonia composed of oil shale processing residues from the Eesti power plant. Detailed mineralogical, chemical and micromorphological analyses using X-ray diffraction, X-ray fluorescence, 29Si nuclear magnetic resonance, scanning electron microscopy and other methods were applied in order to identify the composition of the waste with a focus on formation and transformation of semicrystalline phases in the deposit. The results show progressive formation of calcium-silicate-hydrate (C-S-H) type phase at the expense of silicate minerals and amorphous glass phases with increasing depth and age of the sediments, from about 25% in the upper part of the depository to over 60% in the oldest-deepest part. This demonstrates that over time the high alkalinity of the ash is responsible for initiating natural alkali-activation. The formation of C-S-H-type phases increases the mechanical strength of the sediment and ensures long-term stability of waste deposits. These findings may encourage the use of these ashes in binder or other construction material production or as construction aggregates

Chemical and physical characterization of oil shale combustion emissions in Estonia

In this study, oil shale combustion emission measurements were conducted in a 60 kW(th) Circulating Fluidized Bed combustion test facility located in a laboratory-type environment. A comprehensive set of instruments including a nitrate-ion-based Chemical Ionization Atmospheric Pressure interface Time-of-Flight Mass Spectrometer, a Soot-Particle Aerosol Mass Spectrometer, and a Potential Aerosol Mass (PAM) chamber was utilized to investigate the chemical composition and concentrations of primary and secondary emissions in oil shale combustion. In addition, the size distribution of particles (2.5-414 nm) as well as concentration and composition of gaseous precursors were characterized. Altogether 12 different experiments were conducted. Primary emissions were studied in seven experiments and aged emissions using PAM chamber in five experiments. Combustion temperatures and solid fuel circulation rates varied between different experiments, and it was found that the burning conditions had a large impact on gaseous and particulate emissions. The majority of the combustion particles were below 10 nm in size during good burning whereas in poor burning conditions the emitted particles were larger and size distributions with 2-3 particle modes were detected. The main submicron particle chemical component was particulate organic matter (POM), followed by sulfate, chloride, nitrate, and ammonium. The secondary particulate matter formed in the PAM chamber was mostly POM and the concentration of POM was many orders of magnitude higher in aged aerosol compared to primary emissions. A significant amount of aromatic volatile organic compounds (VOCs) was measured as well. VOCs have the potential to go through gas-to-particle conversion during the oxidation process, explaining the observed high concentrations of aged POM. During good combustion, when VOC emissions were lower, over 80% of SO2 was oxidized either to gaseous H2SO4 (37%) or particulate sulfate (46%) in the PAM chamber, which mimic the atmospheric processes taken place in the ambient air after few days of emission.Peer reviewe

Characterization of different wood species as potential feedstocks for gasification

Received: August 26th, 2020 ; Accepted: January 12th, 2021 ; Published: January 18th, 2021 ; Correspondence: [email protected] paper provides an extended overview of the chemical characteristics of 19 different wood species originating from Estonia. The variation of chemical composition in wood and bark was investigated using a variety of analytical techniques including WD-XRF, ICP-MS, and elemental analysis. Principal component analysis (PCA) was used to observe clustering in the sample set. It revealed a clear data clustering in terms of the wood and bark samples. Wood characteristics exhibit quite narrow ranges, on the other hand the composition of wood bark samples is significantly different and more distributed. The correlations and associations among 27 chemical parameters, including 16 ash-forming elements, were studied. Several significant positive correlations between Cr-Ni-Fe, Ca-Sr, Al-Na-Si-Ti, K-Mg-P, Fe-Zn-Cr-Ni-Cu, Ash-Ca, N-S-P and O-volatile matter were found. Most of the metallic components are negatively correlated with volatile matter, C, H, O and heating value and are positively related to each other, or no significant correlation was identified. Results are compared to literature data and technical quality standards for biomass. Biomass feedstocks availability and composition for gasification process was discussed. Wood samples had higher volatiles content than in bark which is an indication that higher conversion rate and lower gasification temperature can be used. Spruce, pine and black alder barks have higher fixed carbon content than other common species that may increase biochar yield. Commonly available woods like Scots pine, Norway spruce, aspen, birch, black alder and grey alder may considered as suitable feedstocks for gasification because of their low N, S, Cl, and ash content together with high volatile matter, however, relatively high total heavy metals content were found from birch and grey alder barks compared to other hardwoods

Effect of Woody Biomass Gasification Process Conditions on the Composition of the Producer Gas

Using woody biomass in thermochemical gasification can be a viable alternative for producing renewable energy. The type of biomass and the process parameters influence the producer gas composition and quality. This paper presents research on the composition of the producer gas from the gasification of three woody biomass species: spruce, alder, and pine. The experiments were conducted in a drop-tube reactor at temperatures of 750, 850, and 950 °C, using air as the gasifying agent, with equivalence ratios of 0.38 and 0.19. Gas chromatography with a thermal conductivity detector was used to determine the composition of the producer gas, while the production of total organic compounds was detected using Fourier-transform infrared spectroscopy. All three wood species exhibited very similar producer gas composition. The highest concentration of combustible gases was recorded at 950 °C, with an average of 4.1, 20.5, and 4.6 vol% for H2, CO, and CH4, respectively, and a LHV ranging from 4.3–5.1 MJ/m3. The results were in accordance with other gasification studies of woody species. Higher temperatures enhanced the composition of the producer gas by promoting endothermic and exothermic gasification reactions, increasing gas production while lowering solid and tar yields. The highest concentrations of combustible gases were observed with an equivalence ratio of 0.38. Continuous TOC measurement allowed understanding the evolution of the gasification process and the relation between a higher production of TOC and CO as the gasification temperature raised