1,721,137 research outputs found
Resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis in ultrasound cell disruption experiments
No full textMicroalgae have rigid, complex cell walls hindering direct lipid extraction. Cell disruption techniques are used to rupture these cellular structures to increase lipid extraction. Researchers investigating the downstream processing of microalgae do not always have access to microalgal cultivation systems to generate large amounts of fresh microalgal biomass. Using resuspended freeze-dried microalgal biomass as a model laboratory system for concentrated fresh biomass during cell disruption experiments offers greater flexibility in experimental planning and omits investment costs of microalgal cultivation equipment. So far, it however remains unclear whether freeze-dried resuspended biomass can be used as a model laboratory system to represent concentrated fresh biomass during cell disruption and lipid extraction experiments. This paper thus evaluated the suitability of resuspended freeze-dried Nannochloropsis as a model laboratory system for concentrated fresh Nannochloropsis during cell disruption. Ultrasound assisted cell disruption was used as example cell disruption technique and lipid extraction efficiency and free fatty acid content were investigated. Tap water and 3% sodium chloride are both suitable resuspension media for the resuspension of freeze-dried Nannochloropsis. Resuspension duration should be limited (< 120 min) to prevent the formation of free fatty acids. The condition of the biomass (concentrated fresh, or resuspended freeze-dried) prior to ultrasound assisted cell disruption did not influence the resulting lipid extraction efficiency. Resuspended freeze-dried Nannochloropsis biomass in tap water or 3% sodium chloride can thus be used as a model laboratory system for fresh microalgal biomass during research on ultrasound assisted lipid extraction. The generalization of the results to other cultivation conditions, cell disruption techniques, components of interest or microalgal species should be carefully assessed.The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Flanders’ Food and funded by Flanders Innovation and Entrepreneurship (VLAIO) through the cSBR
project EffSep (Grant number HBC.2019.0012)
Ultrasound assisted extraction of Nannochloropsis: Effects on lipid extraction efficiency and lipid stability
No full textUltrasound assisted extraction of microalgal lipids from Nannochloropsis in presence of hexane/isopropanol extraction solvent was studied. The results were compared with adequate control extractions, using the same solvent system, solvent contact time and extraction temperature but in the absence of ultrasound. Ultrasound assisted extraction at 0.45 W/mL and control extractions at elevated temperatures (comparable to the temperature induced by the ultrasound) resulted in similar lipid, free fatty acid and pigment extraction efficiencies and the free fatty acid and pigment content of the lipid extracts was comparable. The control and ultrasound assisted extractions did not influence the lipolytic and oxidative stability of the lipids during extraction. These results indicated that the positive impact of ultrasound assisted extraction can almost completely be attributed to the ultrasound induced increased temperature. Simpler extraction techniques applying moderate heating (+/- 40 degrees C) in presence of lipid extraction solvents are most probably more straightforward to implement industrially compared to ultrasound assisted extraction.The authors want to thank VLAIO and Flanders' FOOD for their funding and support during the EffSep Project [c-SBO project HBC.2019.0012]. The authors wish to thank Dr. Jonas Blockx for proofreading the paper. The authors also wish to thank C´eline Dejonghe for integrating part of the FAME chromatograms
Visualization of pectin in carrot pomace using FTIR microspectroscopy: feasibility of internal standardization
No full textPectins are a group of polysaccharides commonly used in industry as gelling, emulsifying, and stabilizing
agents. Traditionally obtained from apple or citrus peel, the increasing global demand for pectin calls for
the study of alternative sources [1], [2] . Although currently employed in animal feed, carrot pomace, a
by-product obtained after juice production, is considered a good target for pectin extraction [3], [4] .
Nevertheless, modifications on the chemical structure during biomass storage have been reported [5] ,
and there is a limited knowledge on changes occurring during pectin extraction. Industrial exploitation
of carrot pomace requires the development of robust analytical methods to collect information about
the variation in composition through the sample.
FTIR microspectroscopy allows the acquisition of spectral and spatial information simultaneously but is
not widely implemented in biomass samples due to the inherent limitations of the technique.
Uncontrolled physical and chemical phenomena such as changes in sample size, humidity, or
instrumental drift are responsible for spectral variance, hindering the potential of this technique for
quantitative analysis [6] . Data pre-processing methods can remove the inherent variation in FTIR-
spectra but can generate artifacts [7] . Normalization of the spectra based on the signal of an internal
standard could overcome this limitation [8] . Nevertheless, internal standardization is not usually
employed on biological samples due to the difficulty of finding compounds exhibiting no spectral
interference.
This work aims to study the feasibility of internal standardization to develop a spectroscopic method for
pectin determination on carrot pomace. In a first step, a calibration model for pectin determination was
prepared, enriching carrot pomace residues obtained after pectin extraction with different percentages
of pectin and a constant amount of internal standard. Subsequently, the calibration model was tested
on samples subjected to internal standardization and analyzed by FTIR microspectroscopy.
Our results show the potential of this approach in FTIR imaging, where internal standardization could
provide a method to quantitatively assess the spatial distribution of pectin in complex biomass matrices.
The findings open up an attractive prospect of using FTIR microspectroscopy for mapping changes of
target compounds at different stages of extraction.This study is funded by Flanders’ Food and VLAIO in the framework of the EffSep project (Grant number HBC.2019.0012
Visualization of pectin in carrot pomace using FTIR microspectroscopy: feasibility of internal standardization
No full textPectins are a group of polysaccharides commonly used in industry as gelling, emulsifying, and stabilizing
agents. Traditionally obtained from apple or citrus peel, the increasing global demand for pectin calls for
the study of alternative sources [1], [2] . Although currently employed in animal feed, carrot pomace, a
by-product obtained after juice production, is considered a good target for pectin extraction [3], [4] .
Nevertheless, modifications on the chemical structure during biomass storage have been reported [5] ,
and there is a limited knowledge on changes occurring during pectin extraction. Industrial exploitation
of carrot pomace requires the development of robust analytical methods to collect information about
the variation in composition through the sample.
FTIR microspectroscopy allows the acquisition of spectral and spatial information simultaneously but is
not widely implemented in biomass samples due to the inherent limitations of the technique.
Uncontrolled physical and chemical phenomena such as changes in sample size, humidity, or
instrumental drift are responsible for spectral variance, hindering the potential of this technique for
quantitative analysis [6] . Data pre-processing methods can remove the inherent variation in FTIR-
spectra but can generate artifacts [7] . Normalization of the spectra based on the signal of an internal
standard could overcome this limitation [8] . Nevertheless, internal standardization is not usually
employed on biological samples due to the difficulty of finding compounds exhibiting no spectral
interference.
This work aims to study the feasibility of internal standardization to develop a spectroscopic method for
pectin determination on carrot pomace. In a first step, a calibration model for pectin determination was
prepared, enriching carrot pomace residues obtained after pectin extraction with different percentages
of pectin and a constant amount of internal standard. Subsequently, the calibration model was tested
on samples subjected to internal standardization and analyzed by FTIR microspectroscopy.
Our results show the potential of this approach in FTIR imaging, where internal standardization could
provide a method to quantitatively assess the spatial distribution of pectin in complex biomass matrices.
The findings open up an attractive prospect of using FTIR microspectroscopy for mapping changes of
target compounds at different stages of extraction.This study is funded by Flanders’ Food and VLAIO in the framework of the EffSep project (Grant number HBC.2019.0012
Curriculum design for a sustainable future: the case of the new master in materiomics
No full textIn 2022-2023, a new master's program ‘Master of Materiomics’ starts at Hasselt University (Belgium), aimed at students
who want to develop sustainable and innovative materials at the interface of chemistry and physics and on the basis of
both theoretical/computational and experimental approaches (4 possible areas of specialization: circular processes; energy
generation, storage and efficiency; materials for quantum technologies; or materials for innovative healthcare). From the
very beginning the rapidly growing awareness regarding sustainability issues both globally and in this specific field has been
guiding our curriculum design. Accordant with the UHasselt educational policy plan 2022-2029, societal sustainability
challenges and sustainability competences are given an explicit place in the curriculum of the master in materiomics (cf.
Greencomp: e.g., embracing complexity in sustainability, envisioning sustainable futures; Bianchi et al., 2022), both in
specific courses (e.g., Sustainable materials and energy; Sustainable development goals: materials and their management)
and in the 4 specialization pillars (mainly circular processes and energy generation, storage and efficiency). Moreover, an
interdisciplinary educational approach was taken in response to increasingly complex societal issues, which are in part
material-related: climate change, pandemics, innovative and safe communication technologies, the energy transition,
changing industrial processes, innovative space research and finite resources that are becoming depleted. Students are
trained in conceptualizing and developing alternative, sustainable materials that may contribute to solutions for these
grand challenges and which may help the world to remain within planetary boundaries and not to overshoot.
To obtain these goals, interdisciplinary competences are required: while taking the larger societal context into account,
students need to cross boundaries between chemistry and physics, as well as between experimental and
theoretical/computational methods. Interdisciplinarity is gradually introduced throughout the curriculum, building on the
four learning mechanisms from boundary crossing theory (Kluijtmans, 2019, based on Akkerman & Bakker, 2011), i.e.
identification, coordination, reflection and transformation. More specifically, students are introduced to the different perspectives and approaches, making connections between
different perspectives, synthesizing them (e.g. through assignments, group work...), and applying all this to new, complex
material problems (e.g. through a hands-on project, the internship and the master's thesis). In order to maximize the
development of interdisciplinary competences among students, a learning portfolio is used which is discussed three times
a year with a mentor (professor of the master). In addition, however, we want to provide evidence-informed and
systematic support for professors and students w.r.t. interdisciplinary collaboration and competence development
associated with it. To this end, staff members have e.g. followed professional development trajectories regarding both
interdisciplinary and sustainable education. During our action atelier, we will further elaborate on how we hope our
curriculum design will lead to transformative learning by our students and we will also go deeper into some specific courses
and their teaching and assessment approaches. Participants are invited to a) reflect on advantages and obstacles of
interdisciplinary competence development for sustainability education and for their own education (e.g., by means of a
speed boat activity; Pavelin, Pundir, & Cham, 2014) and b) to design interdisciplinary learning activities for their own
courses/educational program according to the four learning mechanisms described above
Pyrolysis of brewer’s spent grain biomass to form functional adsorbers
No full textPYROLYSIS OF BREWER’S SPENT GRAIN BIOMASS TO FORM FUNCTIONAL ADSORBERS
D. BLEUS 1, B. JOOS 2,3, W. MARCHAL 1, D. VANDAMME 1
1 Analytical and Circular Chemistry (ACC), Institute for Materials Research (IMO), Hasselt University, Hasselt, Belgium.
4 Design and Synthesis of Inorganic Nanomaterials (DESINe), Institute for Materials Research (IMO-IMOMEC), Hasselt University, 3590 Diepenbeek, Belgium
3 EnergyVille, Thor Park, 3600 Genk, Belgium
1. Keywords
Biomass, valorisation, pyrolysis, adsorbers
2. Highlights
- Brewer’s spent grain and malt dust biomass streams were extracted using bio-based solvents to recover (poly-)phenolic compounds.
- The extracted biomass was pyrolyzed using a lab-scale pipe furnace setup.
- The resulting biochar was then physically activated to obtain activated carbon (AC).
- The AC adsorbers will further be employed as adsorber material in solid phase separation/purification of (poly-)phenolic compounds.
3. Purpose
The proposed research abstract elaborates a novel, circular valorization methodology for
brewer spent grain (BSG) through green solvent-extraction and subsequent pyrolysis and
activation of the biomass resource to produce activated carbon (AC) materials. Finally, the
obtained AC will be investigated for use as adsorber for separation and purification of
extraction mixtures.
BSG is a nutrient-rich side product obtained from the beer brewing process. Many types of
BSG have proven to be naturally abundant in phenolic compounds, which could find
application as anti-oxidants 1 in a variety of food, feed, non-food products and
pharmaceuticals. As an industrial side stream that exceeds 3.4 million tons per year in the EU
alone 2 , a viable valorization route would create both economic and ecological opportunity.
Malt dust, on the other hand, is a lesser-known and underexplored waste stream that
encompasses all fine particulate matter separated from the freshly germinated and dried
barley. It is captured before the brewing process, and therefore still retains most naturally
present nutrients and extractable components.
To create a sustainable 3 valorization route for these biomass streams, extractions should be
carried out using bio-based or biocompatible solvents, while also minimizing the required
energetic budget.
Biomass-based adsorbers show well-documented potential in traditional solvent purification
and extractive recuperation procedures. 4- 5 Hence, in this project biomass-based adsorber
materials are put forward as a promising tool in the efficient recuperation of solvent after
the extraction step has been carried out. Extraction or ‘washing’ pretreatment steps have an
impact on the obtained pyrolysis products, and can yield increased surface area
carbonaceous materials. 6,7 It is therefore postulated that an optimized extraction process can
have a synergistic effect in the production of high surface area AC materials. Not only would
the successful implementation of these adsorbers boost the applicability of bio-based
solvents in the industry, but it would also increase the utilization of biomass side streams
that would otherwise be discarded as waste in landfills or incineration plants. 8
4. Materials and methods
BSG and malt dust were obtained from a local brewery. The samples were dried at 60°C and
stored at -20°C until further use. Different bio-based solvent systems are prepared and
evaluated for their efficiency. The mixtures were extracted using maceration at 70°C, 90°C,
and 120°C, respectively. The mixture was then centrifuged at 4000 rpm for 30 minutes,
before being filtered off under vacuum. The filtered extracts were then analysed on HPLC-
MS.
The solid biomass precipitate obtained after centrifugation was collected, excess bio-based
solvent was removed by vacuum filtration, and finally dried in vacuo at 60°C to remove
remaining water. The extracted biomass with residual bio-based solvent was then pyrolyzed
in a tube furnace at 700°C, under N 2 atmosphere. The resulting biochar was collected and
yield was determined gravimetrically, before performing physical activation on part of the
biochar material.
Resulting biochar and AC materials were then analysed using BET (Brunauer–Emmett–Teller)
specific surface area using gas adsorption measurement, scanning electron microscopy for
surface morphology, Ultimate analysis for elemental CHNO-composition, and
thermogravimetric analysis for volatiles and ash content determination.
5. Results and discussion
Preliminary results confirm the findings of earlier studies regarding the extraction efficiency
of bio-based solvents as a valid alternative to optimized extraction methods that utilize
classical solvents, such as acetone:H 2 O mixtures. 9 Using an optimized extraction setup at
elevated temperatures (120°C), extraction efficiencies were improved over classical
maceration methods.
Through the combination of centrifugation and vacuum filtration, (poly-)phenolic extracts
have been separated from the extracted solid biomass residue, obtaining pure liquid extracts
suitable for direct analysis on HPLC-MS. Qualitative identification of various (poly-)phenolic
compounds was performed through an optimized separation method on C18 column, with
acidified H 2 O:MeOH elution gradient.
‘Wet’ biomass was pyrolyzed at 700°C and steam-activated at 800°C in small scale
experiments, obtaining AC materials with promising surface areas, exceeding 500 m 2 /g.
6. Conclusions and perspectives
Promising preliminary results confirm the plausibility of the above-mentioned methodology
for circular valorisation of BSG and malt dust biomass. On one hand, phenolic anti-oxidant
compounds were qualitatively extracted from BSG and malt dust biomass streams, using
green solvents.
The obtained AC materials will be further analysed for chemical and phyiscal functionality,
with additional optimizations of the lab-scale pyrolysis and activation process still to be
performed. Future perspective includes the setup of small-scale preparative phenolic
isolation, and elution tests, which will be performed with the obtained AC adsorbers.
7. References
[1] L. F. Guido, Food Bioprocess Technol., 2017, 10, 1192–1209.
[2] J. Steiner, Eur. Food Res. Technol., 2015, 241, 303–315.
[3] J. C. W. P.T. Anastas, Oxford University Press, 1998.
[4] B. Chen, Environ. Sci. Technol., 2008, 42, 5137–5143.
[5] J. Li, J. Hazard. Mater., 2014, 280, 450–457.
[6] W. Vercruysse, Journal of Analytical and Applied Pyrolysis, 2021, 159, 105294.
[7] J. Castro, Polymers, 2020, 12(1483), 1–13.
[8] A. Korus, Fuel Process. Technol., 2019, 185, 106–116.
[9] A. Zuorro, Processes., 2019, 7(3), 126
The production and characterization of magnetic microwave absorbers for microwave-assisted pyrolysis
No full textMicrowave absorbers (MWAs) are materials with the capability to convert microwaves into heating energy due to their high dielectric permittivity and/or magnetic permeability. Due to these properties, these materials are able to generate heat from microwave energy upon absorption. In this study, various microwave absorbers were used for microwave-assisted pyrolysis of hardwood. The microwave absorbers used in this study originated from commercial activated carbon (Chemviron’s pulsorb WP260 AC) and were modified through magnetite (Fe3O4) addition. Three variables (magnetite addition level: 5 and 20 wt.%, addition method: in-situ co-precipitation and physical blending and washing agent: water and ethanol/water) were tested. The resulting microwave absorbers were evaluated on the pyrolysis performance of hardwood in a Milestone Flexiwave microwave reactor (Power: 400 W; Residence time: 37 min; Pressure: 100 – 500 mbar; Total reactor loading: 20 g) with 10 wt.% MWA addition. The biochar yield varied from 24 wt.% and 89 wt.% and seemed to be significantly influenced by the synthesis method rather than Fe3O4 level. The microwave absorbers with physically blended Fe3O4 resulted in the best pyrolysis performance. All other modified MWAs performed less than the original commercial WP260 AC sample. The resulting biochars from the experiments with physically blended Fe3O4 AC and WP260 were characterized by elemental composition (C,H,N,S,O and ash content) after physical separation from the MWA. Furthermore, the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) in the selected biochars were evaluated. The results suggest that physical Fe3O4 blending seems to cause a reduction of total PAHs content, mainly by reduction of the pyrene content in the biochar. Future experiments will involve the study concerning the possibility of magnetic separation of the MWA from the produced biochar. This will provide us more possibilities when scaling up the microwave-assisted pyrolysis process
Dissolved air flotation of a native Cuban Chlorella sp. using chitosan: influence of extracellular organic matter on coagulant dose and floc properties
No full textBridging the gap between biochar’s physicochemical characteristics and plant growth
No full textIndustrialized farming relies heavily on the use of unsustainable synthetic fertilizers to attain their required plant production goals, this usage has several adverse side-effects e.g. eutrophication of water bodies or the increase of atmospheric nitrogen levels [1]. The last decade, the attention of the scientific community has shifted to biobased fertilizers, such as biochars, which can be produced via simple and low-cost methods, while being both energy-negative and carbon neutral. In this regard, Vercruysse et al. [2] synthesized biochars based on extracted common ivy trimmings. Physicochemical characterization of the biochars showed that they had great potential as effective fertilizers, however this was not supported by plant-growth experiments yet.
The aim of this study is to assess whether common ivy-based biochars would have beneficial effects on seedling development. To assess this, lab-scale plant growth experiments on Arabidopsis thaliana seedlings were performed and correlations between important biochar properties and plant development were established. Two different biochar pyrolysis temperatures were tested, 400 and 700 °C and the effect of two different valuable compounds extractions, ethanol extraction and steam distillation, on the biochar’s effectiveness was investigated. This was done via a lab-scale 96-well plant growth experiment, in which 0.5 and 1% of biochar were added to an adapted ¼ Murashee and Skoog plant growth medium. After 7 and 10 days of plant growth seedlings were harvested. After 7 days of growth, phenotypical analysis was performed and the plant’s cell cycle regulation was investigated [3]. Next, plants cultivated for 10 days were also phenotypically analyzed. Furthermore, changes in the plant growth medium due to biochar addition, were evaluated through leaching experiments.
K-leaching from the biochars caused the growth medium’s pH and conductivity to increase significantly in the first 7 days of plant growth. This leaching caused the plants to express initial growth stress responses (Pearson = 0.930), proven by changes in their cell cycle regulation. The second part of the investigated cultivation period, 7-10 days, showed total recovery of the seedlings subjected to biochars produced at 400 °C. Moreover, significant increases in plant fresh weight were established at 1% biochar application rate. Besides that, biochars produced at 700 °C did not significantly affect plant development compared to the control group. At high (1%) biochar loading, low-temperature biochars improved plant development significantly better than high-temperature biochars. This was due to the phosphate availability in high temperature biochars decreasing significantly, which would decrease several plant stress remediation mechanisms.
In conclusion, low-temperature (400 °C) biochars significantly outperform high-temperature (700 °C) in terms of plant development. Furthermore, valuable compound extractions are perfectly suitable as a pretreatment process for common ivy trimmings as they do not diminish the biochar’s performance as soil amendment.This work was financially supported by Research Foundation Flanders (FWO SB – 1S92020N
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