Mechanical disintegration pretreatment

It seemed reasonable to supplement our results obtained with low-DP linters cellulose powders by some experiments with high-DP cotton linters, given analogous pretreatments in the original state and after mechanical disintegration. 

Acid hydrolysis of these samples led to the results to be expected, i.e., a lowering of LODP and residue value by NH3 pretreatment and mercerization as well as by mechanical disintegration prior to the hydrolytic treatment (Table XII). With regard to residue value, an NH3 pretreatment again proved to be more efficient in enhancing accessibility than a mercerization, while the rate constant of chain-length degradation was increased somewhat more by mercerization. 

With the samples at first mechanically disintegrated, all the statements regarding the influence of an NH3 and an NaOH pretreatment were confirmed (Table XII). In any case, the previous mechanical disintegration decreased the rate of enzymatic attack as compared with the appropriate nondisintegrated samples. Probably some homification and/or change in pore structure occurs during mechanical disintegration in the dry state. 

NFC depend on the cellulose source. Besides, it was found that the degree of crystallinity of NFC slightly decreases with an increase in the number of passes through the high-pressure homogenizer (Iwamoto et al., 2007). Such pretreatments as enzymatic hydrolysis and TEMPO-oxidation do not change the crystalline stracture of the final NFC. However, the nanofibrils produced after preliminary carboxymethylation have lower crystallinity and size of crystallites than NFC obtained by conventional mechanical disintegration. 

The DP decreases slightly after mechanical disintegration of ceUulose materials. However, after bio- or chemical pretreatments a sharp reduction in DP value takes place. For example, the DP value of the dissolving pulp decreased from 1280 to 820 after pretreatment with cellulolytic enzyme (0.2 mg/g) and the subsequent homogenization (Henriksson et al., 2007 Henriksson, 2008). 

Cellulose nanofibers, also called micro/nanofibrillated cellulose (MFC/NFC), are obtained by mechanical disintegration after the raw cellulosic materials were chemically or enzymatically pretreated to get pure cellulose. Thus, the MFC has a high aspect ratio with a length over 1000 nm including crystalline and amorphous cellulose (Siro and Plackett, 2010). Microfibrillar cellulose (MFC) shows more commercial production availability than hydrolyzed CNC (Brinchi et al., 2013). 

Catalyst preparation is crucial in successful Fischer-Tropsch synthesis. Appropriate catalyst composition and delicate pretreatment and operating conditions are all necessary preconditions to achieve the desired results. Catalyst disintegration brought about by oxidation and carbide formation is a serious problem that can be prevented only by using catalysts with adequate chemical and mechanical stability under appropriate operating conditions. 

Cellulose EFB could disintegrate in order to produce cellulose nanofiber (CNF). In history, there are various techniques studied in order to obtain pure, new, and improved EFB fiber. The purity and quality of the final product is distinguished from the very beginning of each process integration. There are several processes in nanofiber isolation that include pretreatment, bleaching, and extraction of cellulose nanofiber suspension which can be done through hydrolysis using chemical or mechanical process. 

The application of an external pulsed electric field (PEF), the induced local structural changes of the cell membrane, and also the increase in permeability due to the appearance of permanent membrane pores were found to positively affect any subsequent drying processes of porous plant materials. PEF provides an alternative to the mechanical, thermal or enzymatic cell disintegration of plant tissue, providing a short-term (milliseconds), low-energy pretreatment (<10kJkg-Y... 

Mechanical pretreatment is usually required for high solid content feedstocks before any other kind of pretreatment, and actually refers to milling, through which particle size reduction of feedstocks is accomplished. Mechanical pretreatment disintegrates the solids and/or decreases the particle size of the biomass and so increases the surface area, resulting in increased substrate availabiUty for the microorganisms. Consequently, microbial growth and AD process are improved (Ariunbaatar et al., 2014). 

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