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Biocarbon mechanochemical activation

Zbigniew Najzarek 1Janusz Wełnowski Remigiusz Petrich 2

1. Opole University, Independent Department of Process Engineering (KIP), Dmowskiego 7-9, Opole 45-365, Poland
2. Gorden Sp. z o.o., Azalowa 23, Białe Błota 86-005, Poland


At present, biocarbon (biocoal, charcoal, torriiefied biomass, as well as hydrochar)  can be produced efficiently and economically by heat treatment (i.e. via pyrolysis, carbonization or torrefication) as well as by hydrothermal (HTC) or vapothermal (VPC) carbonization of the lignocellulosic biomass, such as: wood, sawdust, straw, peat, crop residues and other waste plant residues, municipal and industrial waste,  moses, and related substrates. In particular, straw as the abundant and renewable agricultural residue that are not useful in obtaining food constitute an important source of  precursors for the biocarbon production especially after pre-treatment in a new mill introduced here.. Biocarbon thus produced has no heavy metals, contains almost no sulfur, very little nitrogen, low ash, and carbon dioxide emission from such source is not counted as the greenhouse gas emission. Because storage and transportation are safe here, functional infrastructures were established to deliver biocarbon from producers to consumers which promote its use.   The carbonization processing were performed within a wide temperature range, in a controlled gas atmosphere, under a controlled pressure, and with the optimal presence of a catalyst. Therefore, the structure and properties of the biocarbon can be varied widely and tailored to the  specific requirement of each application. The biocarbons are generally   composed of non-carbonized and carbonized organic matters and their relative fractions are affected by the above  processing conditions. The structure varies from amorphous to amorphous-crystalline, and the biocarbons represent essentially a nanocomposite made up of amorphous carbon, graphite nanocrystallites and graphene layers. Moreover, as-produced biocarbon can maintain the  biomorphic pore  microstructure of the lignocellulosic substrate which efficiently increases its performance in various applications. However, so far received biocarbons consist of poorly structured agglomerates of  biocarbon-derived nanoparticles. The properties of these agglomerates are not improved in  environments of  the well-known mills and mechanochemical reactors. In addition, such conducted mechanochemical processes run at the nanoscale reactants slowly and generallny inefficiently. Instead, they cause   the destruction of the above mentioned microstructure  of technologically preferred reactants. On the other  hand,  nanoparticulete materials that can be prepared from conventional chemical reactants via the carbothermal processing as well as carbon nanotube fibers  that were able to isolate from the environment of the carbothermal processing of the lignocellulosic substrate showed very favorable performances. Therefore, the introduction here of a new, efficient mechanochemical processing has essential  importance. Apart from the pore structure, the functional groups on the biocarbon surface affect significantly the biocarbon properties However, the known physical and chemical activatiopn methods used so far for the case of biocarbon does not allow control of  such changes in its properties. Known methods do not allow even an effective micronization of the biocarbon in spite of these facts, that such micronization enables optimization  of the majoraty of biocarbon applications and runs much easier than micronization of the starting biomass. According to the literature [V. Soloiu, et al.., Energy 36(2011)4353-4371], the most efficient micronization of biocarbon led .to polidisperse size distribution with average size of particie 10.5 mm and significant fractions of larger particles over 50 mm and up to 200 mm which limits such microparticle application range, e.g. as the diesel engine fuel. This micronization was carried out in a laboratory scale multi-step slow batch process of biocarbon slurries from selected wood.. Comparatively, in this work micronization proceed in the solid phase, which allowed efficient mechanochemical activation of as-formed  microparticles, as a continuous, well-controlled process on an industrial scale at  a rate about 1 kg/s. The literature average size of particle 10.5mm was attained here far from the maximal performance of the new supersonic rotor mill [J.Wełnowski, et al.., Patent application (2013)], within the monodisperse size distribution, without the fraction of  larger particles. Such process of efficient micronization with mechanochemical activation  was carried out for biocarbons prepared from the rye straw as well as from a number of representative and renewable lignocellulosic waste. These waste were pyrolysed according to the literature method [C. Schmedt, G. Bogdanow, EP 2565255(2013)]. As a result, this wok introduces a new method of micronization and mechanochemical activation of biocarbon. This method is characterized by a very high efficiency. Such activated microparticles can improve the quality of biocarbon-derived products, especially electrochemical, sorptive, composite, catalytic, as well as fuel, chemical reagents , and fertilizers. This method is currently being extended for the nanoprocessing purposes


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Related papers

Presentation: Oral at Nano PL 2014, Symposium A, by Zbigniew Najzarek
See On-line Journal of Nano PL 2014

Submitted: 2014-06-30 04:26
Revised:   2014-10-07 15:39