Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/38754
Title: Activated carbon adsorbers from NADES-extracted brewer’s spent grain and malt dust biomass
Authors: BLEUS, Dries 
JOOS, Bjorn 
MARCHAL, Wouter 
VANDAMME, Dries 
Issue Date: 2022
Source: CRF-ChemCYS, Blankenberge, Belgium, 12/10/2022-14/10/2022
Abstract: Keywords Biomass; valorisation; pyrolysis; adsorption materials; activated carbon This investigation elaborates on a sustainable two-step valorization method for obtaining specialty bio-chemicals and activated carbon materials from biomass side products of the beer brewing industry. Two specific biomass streams are investigated: Brewer’s spent grain (BSG), a nutrient- and antioxidant-rich side product obtained after the beer brewing process (3.4 million tons per annum in the EU ), and malt dust (MD), an underexplored biomass stream obtained from the barley malting process. As a two-step valorization route, antioxidant phenolic compounds are first hydrothermally extracted from these biomass streams using non-toxic, bio-based natural deep eutectic solvents (NADES), after which the spent biomass is further pyrolyzed and activated to obtain activated carbon (AC) adsorption materials . These biomass-based AC are proposed as a promising tool for separation of phenolic extracts and NADES solvent recuperation. Dry biomass was extracted using a hydrothermal extraction method at 120°C. Two choline chloride-based NADES solvents (malic acid:choline chloride, glycerol:choline chloride) were evaluated for their efficiency against a ‘conventional’ acetone-water solvent mixture. Filtered extracts were analysed on HPLC for contents of four major phenolic components (caffeic acid, syringaldehyde, p-coumaric acid and ferulic acid). Next, the spent biomass was pyrolyzed at 700 °C, and physically activated using CO2 at 800 °C. The produced AC were then analysed using nitrogen physisorption experiments to obtain their BET (Brunauer–Emmett–Teller) specific surface area, scanning electron microscopy for surface morphology, ultimate (CHNSO) analysis, and thermogravimetric analysis for volatiles and ash content determination. To test the applicability of AC for separation of solutes from NADES solvents, preliminary batch ad- and desorption tests were performed. Hydrothermal extractions performed with NADES generally offered favourable results for both biomass streams (22.3 µg/g caffeic acid, 4.7 µg/g syringaldehyde, 91.8 µg/g p-coumaric acid and 272.0 µg/g ferulic acid for BSG, 33.5 µg/g caffeic acid, 6.5 µg/g syringaldehyde, 17.2 µg/g p-coumaric acid and 42.3 µg/g ferulic acid for MD). These results are in line with, or exceed the findings of earlier studies . Results also showed that the hydrothermal process using NADES solvent could serve as a valid alternative to extraction methods with classical solvents. Elemental analysis, ICP-OES and FT-IR analysis showed (slight) alterations in the physico-chemical properties of AC obtained from spent biomass. BET surface areas of the produced AC’s reached up to 1658 m2/g for BSG biomass, and up to 1198 m2/g for malt dust, representing an uptick of 16% and 33% over the untreated biomass AC from each stream, respectively. In conclusion, through the proposed two-step valorisation method of BSG and MD biomass, phenolic anti-oxidant compounds were successfully extracted from BSG and malt dust biomass streams, using green solvents and a novel hydrothermal extraction method. Secondly, the obtained AC’s from spent biomass were characterized with excellent surface areas that exceeded those of untreated biomass. Physisorption tests will be performed to indicate the ad- and desorption capacity of the produced AC. L. F. Guido. et al. Techniques for Extraction of Brewer’s Spent Grain Polyphenols: a Review. Food and Bioprocess Technology, 10(7), 1192–1209 (2017). J. Steiner. et al. Brewer’s spent grain: source of value-added polysaccharides for the food industry in reference to the health claims. European Food Research and Technology. 241(3), 303–315 (2015). J. Li. et al. A comparison of biochars from lignin, cellulose and wood as the sorbent to an aromatic pollutant. Journal of Hazardous Materials. 280, 450–457 (2014). Y. Cai. et al. Adsorption and Desorption Performance and Mechanism of Tetracycline Hydrochloride by Activated Carbon-Based Adsorbents Derived from Sugar. Molecules. 24 (2019). K. Dubey. et al. Adsorption-Desorption Process Using Wood-Based Activated Carbon for Recovery of Biosurfactant from Fermented Distillery Wastewater. Biotechnological progress. 21, 860−867 (2008). A. Zuorro. et al. Water-organic solvent extraction of phenolic antioxidants from brewers’ spent grain. Processes. 7(3), 126 (2019). McCarthy, A. L. et al. The hydroxycinnamic acid content of barley and brewers’ spent grain (BSG) and the potential to incorporate phenolic extracts of BSG as antioxidants into fruit beverages. Food Chemistry. 141(3), 2567–2574 (2013).
Document URI: http://hdl.handle.net/1942/38754
Category: C2
Type: Conference Material
Appears in Collections:Research publications

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