Zum Recycling von Span- und MDF-Platten

Franke, Robert; Roffael, E.

doi:10.1007/s001070050268

Cited by 13 publications

(7 citation statements)

References 3 publications

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“…The high pH of the MDF samples likely originates from ammonium hydroxide, which is converted from ammonia in watery solutions. The ammonia, in turn, is hydrolytically cleaved from the UF-resin polymers [18,19]. For all samples, the amount of formic and acetic acid rises with increasing severity.…”

Section: Influence Of the Severity On The Hydrolysis Reactions Of Thementioning

confidence: 95%

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Fractionation of Waste MDF by Steam Refining

Hagel

Saake

2020

Molecules

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In view of the expected increase in available waste medium-density fiberboard (MDF) and the current insufficient and unsatisfactory disposal capacities, efficient ways of recycling the waste material need to be developed. In this study, the potential of steam refining as a method to hydrolyze the resins, isolate fibers, and obtain a hemicellulose-rich extract available for further utilization in the context of a biorefinery was assessed. Two different MDF waste samples, as well as poplar (Populus spp.) and spruce (Picea spp.) wood chips for benchmarking, were treated over a severity range from 2.47 to 3.95. The separated fiber and extract fractions were analyzed with regard to yield, content of carbohydrates, acids, degradation products, and nitrogen. A fiber fraction of more than 70% yield and an extract containing up to 30% of carbohydrates for further processing can be gained by steam-refining waste MDF. At low severities, most of the nitrogen-based compounds are solubilized. Increasing the severity leads to a decrease in nitrogen in the extract as the nitrogen compounds are converted into volatiles. A non-hydrolysable resin residue remains on the fibers, independent of the treatment severity. In comparison to the benchmark samples, the extract fraction of waste MDF shows a high pH of 8 and high amounts of acetic and formic acid. The generation of furfural and 5-hydroxymethylfurfural (5-HMF) on the other hand is suppressed. Distinct differences in carbohydrate hydrolysis behavior between waste MDF and conventional wood can be observed. Especially, the mannose-containing constituents seem to be resistant to hydrolysis reactions in the milieu created in MDF fractionation.

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Section: Influence Of the Severity On The Hydrolysis Reactions Of Thementioning

confidence: 95%

“…While the highest removal rate of cured resins can be achieved using acidic solutions [16], it is still possible to remove up to two-thirds of cured resin using only water at temperatures below 100 • C [17]. More intense reaction conditions, as they are found in steam treatments, can further improve the resin hydrolysis [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Fractionation of Waste MDF by Steam Refining

Hagel

Saake

2020

Molecules

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“…Wan et al [13] mentioned that there have been developed several methods for reconstituting the waste from PBs and other medium density fiberboards (MDF) in order to solve the problem of recycling the wood composites. The processing can be chemically thermomechanical [14,15], hydrothermal [16][17][18], chemical [19] or mechanical [20][21][22][23][24]. According to Wan et al [13], it was confirmed by research results that common types of urea-formaldehyde (UF) 2 of 16 and phenol-formaldehyde (PF) resins are suitable for manufacturing PBs and MDF from recycled wood materials using conventional technology.…”

Section: Introductionmentioning

confidence: 99%

Particleboards from Recycled Wood

Iždinský

Vidholdová

Reinprecht

2020

Forests

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The effective recovery of wood waste generated in wood processing and also at the end of wood product life is important from environmental and economic points of view. In a laboratory, 16 mm-thick three-layer urea–formaldehyde (UF)-bonded particleboards (PBs) were produced at 5.8 MPa and 240 °C and with an 8 s/mm pressing factor, using wood particles prepared from (1) fresh spruce wood (C), (2) a mixture of several recycled wood products (R1), and (3) recycled faulty PBs bonded with UF resin (R2). Particles from spruce wood were combined with particles from R1 or R2 recyclates in weight ratios of 100:0, 80:20, 50:50 and 0:100. In comparison to the control spruce PB, the PBs containing the R1 recyclate from old wood products were characterized by lower thickness swelling after 2 and 24 h (TS-2h and TS-24h), lower by 18 and 31%; water absorption after 2 and 24 h (WA-2h and WA-24h), lower by 33 and 28%; modulus of rupture in bending (MOR), lower by 28%; modulus of elasticity in bending (MOE), lower by 18%; internal bond (IB), lower by 33%; and resistance to decay determined by the mass loss under the action of the brown-rot fungus Coniophora puteana (Δm), lower by 32%. The PBs containing the R2 recyclate from faulty PBs were also characterized by a lower TS-2h and TS-24h, lower by 45% and 59%; WA-2h and WA-24h, lower by 61% and 51%; MOR, lower by 37%; MOE, lower by 17%; and IB, lower by 33%; however, their biological resistance to C. puteana was more effective, with a decreased Δm in the decay test, lower by 44%.

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“…Fractionation is a necessary step to enable a material recycling of waste MDF. Using hydrothermal or steam-based treatments it is possible to hydrolyze the urea-formaldehyde (UF) based resins [10][11][12][13][14], which make up the majority of the resins used in MDF production [15]. To compare chemical and structural changes in differing steam-based treatments of lignocellulosic material, the severity factor, which combines the two main process parameters treatment duration and temperature, can be used [16,17].…”

Section: Introductionmentioning

confidence: 99%

“…The liquid fraction contains solubilized carbohydrates and lignin as well as a high amount of nitrogen and acids (acetic and formic). The pH of the liquid extract of around 8 is high in comparison to liquid fractions of steam treated native lignocellulosic material, due to a high amount of ammonium hydroxide following the degradation of the urea-formaldehyde resins [12,13]. As the fiber fraction accounts for the major fraction after the steam refining treatment, the development of an economically viable recycling pathway for the fibers is of prime interest for the advancement of material recycling of waste MDF.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

Hagel

Joy

Cicala

et al. 2021

Waste Biomass Valor

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Currently, most of the collected waste medium-density fiberboards (MDF) is incinerated or landfilled, as economically viable recycling methods are yet to be developed. By steam refining waste medium-density fiberboards (MDF), it is possible to hydrolyze the incorporated resins and isolate a high yield fiber fraction. Further refining of the steam treated fibers might enable the fibers to be utilized in applications such as paper packaging, facilitating a cascading use of the waste material stream. To this end, intimate knowledge of the material is needed. In this study, the steam refined fibers of two waste MDF samples containing differing amounts of softwood and hardwood underwent refining and beating. The resulting fibers were characterized regarding their morphology and paper test sheets were produced to evaluate their strength (compression-, tensile- and tear-strength). Distinct differences in response to refining between the MDF samples were apparent. For the sample with the higher hardwood share an increase in strength properties with increasing steam treatment severities could be observed and it was possible to produce test sheets with comparable compression strength to recycled pulp for industrial corrugated paperboard. For the sample with a higher share of softwood, the steam treatment severity did not show any influence on fiber morphology or paper properties, and the resulting paper strength was low in comparison to the other steam refined waste MDF sample. Graphic Abstract

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Zum Recycling von Span- und MDF-Platten

Cited by 13 publications

References 3 publications

Fractionation of Waste MDF by Steam Refining

Fractionation of Waste MDF by Steam Refining

Particleboards from Recycled Wood

Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

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