Cellulose biological hydrolysis

Useful reviews of the application of near infrared -to the study of various classes of compound are as follows organic compounds, polymers, silicon compounds, pharmaceuticals," food, - petrochemicals, - agricultural products, -" surface hydrolysis of cellulose, biological and medical. ... 

Urea in kidney dialysate can be determined by immobilizing urease (via silylation or with glutaraldehyde as binder) on commercially available acid-base cellulose pads the process has to be modified slightly in order not to alter the dye contained in the pads [57]. The stopped-flow technique assures the required sensitivity for the enzymatic reaction, which takes 30-60 s. Synchronization of the peristaltic pumps PI and P2 in the valveless impulse-response flow injection manifold depicted in Fig. 5.19.B by means of a timer enables kinetic measurements [62]. Following a comprehensive study of the effect of hydrodynamic and (bio)chemical variables, the sensor was optimized for monitoring urea in real biological samples. A similar system was used for the determination of penicillin by penicillinase-catalysed hydrolysis. The enzyme was immobilized on acid-base cellulose strips via bovine serum albumin similarly as in enzyme electrodes [63], even though the above-described procedure would have been equally effective. 

As mentioned in the biological—biochemical section, another approach to improve alcoholic fermentation combines saccharification and fermentation, ie, simultaneous saccharification and fermentation (SSF). Enzyme-catalyzed cellulose hydrolysis and fermentation to alcohol takes place in the same vessel in the presence of enzyme and yeast (50). Reduced fermenter pressures and enzyme and yeast recycling result in 70 to 80% ethanol yields. These process modifications, coupled with more energy-efficient distillation and heat exchanger improvements, are projected to make fermentation ethanol from low value biomass competitive with industrial ethanol (51). 

Cellulose acetate (CA), of poor chemical stability, tends to hydrolyze over time, is subject to biological attack, and can operate at only a limited pH range of 3.0 to 6.5 at 0 to 30°C. It is widely available at low cost and is tolerant of continuous low-level chlorine exposure, such as is found in city water). Often blended with cellulose triacetate (CTA), which provides reasonable hydrolysis and compaction characteristics. 

Depolymerization of the biopolymer structure is an issue in almost all utiUzation concepts. The established chemical technology using cellulose as a base material is a significant exception. Recovery of proteins is proving to be a second major exception. For the most, pari the carbohydrate structure needs to be broken down into useful monomers like glucose or xylose. Over the years, the assessment of hydrolysis with catalysts, both mineral and biological, has been evaluated with a range of biomass feedstocks. 

In the absence of active biological attack, the two dominant processes leading to natural deterioration of cellulose are acid-promoted hydrolysis and oxidation. The latter is quite slow, and we would expect cellulosic artefacts that are above neutrality and kept in a stable environment to remain in relatively good condition for hundreds of years. However, those that are somewhat acidic can show significant signs of deterioration within a few decades. 

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