Fractionation of Waste MDF by Steam Refining

Abstract

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.

Influence of Adding Offcuts and Trims with a Recycling Approach on the Properties of High-Density Fibrous Composites

“…Furthermore, to reduce wood wastes disposed of in landfills, MDF can be produced from up to 100% recovered fibers, or even of old newsprint fibers [ 17 , 18 ]. Also, there are suggestions to re-use the post-used MDF fibers in MDF production after their steam refining conversion [ 19 ]. This approach sounds to be more reasonable than the deeper processing of the MDF recovered fibers to bioethanol production [ 20 ].…”

Maize Silage Pretreatment via Steam Refining and Subsequent Enzymatic Hydrolysis for the Production of Fermentable Carbohydrates

“…Therefore, the usage of acidic catalysts, such as SO 2 , is indicated for softwood. For poplar wood, acetic acid values of 1% to 3% are presented [ 45 ], whereas values below 1% are described for analogous experiments with softwood without catalysts [ 42 ]. Therefore, with values higher than 1%, an occurring autohydrolysis can be suggested for ensiled maize, and the usage of acidic catalysts is not needed, which is also beneficial in terms of cost considerations.…”

“…This process is described by different authors for the production of chemical pulp [ 38 ], for the pretreatment of LCB, such as poplar wood [ 39 , 40 ], corn stover [ 41 ], spruce wood [ 42 ], and spruce forest residues [ 43 ]. Furthermore, possibilities for the utilization of alkaline-extracted steam-refining lignin in phenol-formaldehyde resins [ 44 ] and fractionation approaches for the recycling of waste medium-density fiberboards (MDF) by steam refining are reported [ 42 ]. The steam-refining process was also compared with the steam explosion processes by Schütt et al [ 45 ].…”

Characterization of Zinc Oxide-Urea Formaldehyde Nano Resin and Its Impact on the Physical Performance of Medium-Density Fiberboard

“…Nanoparticles are an example of materials that lead to attractive results, such as a decrease of swelling and lower mass gain when in contact with water [ 8 ]. The main aims are to study the physical properties, i.e., water absorption and thickness swelling of MDF, by examining the effects of using different ZnO nanoparticles weight percentages in its resin content.…”