Cellulose milling

Processes have been developed in North America to pilot scale growing the bacterium Cellulomonas or the fungus Trichoderma on pre-treated milled cellulosic material in conventional fermentors, ie in a liquid medium. However, preparation costs are considerably higher than with solid-substrate fermentations. 

Cellulase is a complex of enzymes showing various types of activities. Cellulose substrates include highly resistant crystalline forms such as cotton, various types of microcrystalline cellulose such as Avicel and hydrocellulose, sulfite pulps such as Solka Floe, as well as filter paper and cotton fabrics. More susceptible substrates include swollen or reprecipitated cellulose, cellophane, and ball-milled cellulose. Most susceptible are the soluble derivatives (of low D.S.) such as carboxymethylcellulose and cellulose sulfate. It is not surprising that there are many assay methods to detect or measure cellulase (9). These methods differ markedly in sensitivity, and in cellulase components detected, depending on the substrate used, the effect measured, and the duration and conditions of... 

In heated and milled cellulose, we have a material which is by far the best substrate yet found for cellulose saccharification, where the major goal is to obtain high glucose concentrations at a rapid rate. 

Screen Analysis of the Substrate. The milled cellulose was screen analyzed in a Ro-Tap Testing Sieve Shaker (The W. S. Tyler Company, Cleveland, Ohio) using a series of 40, 60, 100, 120, 170, 200, and 270 mesh U.S. Standard Screens sifting for 45 min. plus an additional 5 min. after the first weight to check the reproducibility of weights of the screened fractions. Both the weights checked very well. The same procedure was followed in the case of SF, SF-H, SF-HM, SF-MH, and Sweco 70 samples, all of which were subsequently tested. Summary of screen analyses reports is presented in Table II and Figure 9. 

Figure 21. Effect of milling cellulose in contact with cellulose on saccharification...

Kocherbitov, V., Ulvenlund, S., Kober, M., Jarring, K., Amebrant, T., 2008. Hydration of microcrystaUine cellulose and milled cellulose studied by sorption calorimetry. Journal of Physical Chemistry B 112, 3728-3734. 

The conversion of ball-milled cellulose, glucose and fructose into micro-ciystalline lactic acid and 5-hydro g methylfurfural in water, catalysed by lead(ii) nitrate, has been reported (Scheme 22.5). The process involves a multistep cascade including the hydrolysis of cellulose to glucose, the isomerisation of glucose to fructose, retro-aldol fragmentation of fructose to trioses and their subsequent conversion to lactic acid lead(ii) catalyses both the conversion of glucose to fructose and the multistep cascade from fructose to lactic acid. The capacity of lead(ii) to be chelated by... 

Liu et al. used the same pathway to produce hexane from cellulose. With an Ir-ReOySiO catalyst combined with a H-ZSM-5 zeolite in a biphasic system (H O—dodecane), they were able to convert ball-milled cellulose and microcrystalline cellulose to hexane in one pot with yields up to 83% and 78%, respectively [179]. The catalytic reaction proceeds via the formation of sorbitol from cellulose afterward it undergoes hydrogenolysis into hexane. Independently... 

Besides, powders of microciystalline and nano-cellulose, ball-milled cellulose and some others also can be used. The dry samples of the equal mass are pressed into tablets that are used for WAXD experiments. The conditions for preparation of the tablets should... 

The degree of crystallinity can vary from 0 for non-crystalline sample (e.g., ball-milled cellulose] to 1 for hypothetical macrocrystals of cellulose. Minimal and maximal values of crystallinity index (CrI] of MCC Avicel PH-101 obtained by various researchers using different methods (Park et al., 2010 Terinte et al., 2011] and degree of crystallinity of this sample are shown in Fig. 7.6. 

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