Effect of Particle Size on the Kinetics of Enzymatic Hydrolysis of Microcrystalline Cotton Cellulose: a Modeling and Simulation Study

Abstract

As the bioconversion of cellulosic substrate to fuels is essential to suppress the dependence on conventional fossil fuels, development of new improved bioprocess engineering techniques are requisite for fulfilling the rising demand of biofuels throughout the world. For this purpose, the effect of particle size on enzymatic hydrolysis of cotton cellulose has been explored in great detail. The model simulations for the enzymatic hydrolysis of microcrystalline cotton cellulose of different concentrations (0.25-20 mg/ml) were performed for the average particle size ranging from 0.78 to 25.52 μm. A highest glucose yield (99.8%) was observed for the smallest particle size of 0.78 μm in 50 h of enzymatic hydrolysis. Effect of inhibition (competitive and non-competitive) on glucose yield was analyzed through the incorporation of product inhibition in the kinetic model. The extent of cleaving of 1-4 glycosidic bonds by cellulase was quantified by degree of polymerization (DP) of cotton polymers which also indicates that faster scission of bonds can be observed under competitive inhibition and, hence, more glucose yield. The model simulations shows that particle size reduction may be useful for reducing the long residence time required for the hydrolysis step in the bioconversion of cellulose to ethanol.

Biodegradation of Functionalized Nanocellulose

“…We note that LC-CNF samples experienced more extensive overall biodegradation than DA-CNF samples despite LC-CNF samples reaching higher DS surface values (max 2.46) than DA-CNFs (max 0.43). This behavior is a direct result of the production of HCl during CNF functionalization with acyl chlorides, which reduces cellulose chain length and particle size. ,− This decrease in the chain length increases the overall biodegradability of cellulosic materials by offering more sites/surface area (e.g., chain ends) for the initiation of enzymatic attack. ,, In contrast, esterification using carboxylic acid reagents as used in the synthesis of DA-CNFs does not produce HCl at the site of functionalization, limiting damage to the cellulose chain, thereby producing DA-CNF samples with lower DS surface values, which undergo a smaller degree of biodegradation.…”

“…63,94−97 This decrease in the chain length increases the overall biodegradability of cellulosic materials by offering more sites/surface area (e.g., chain ends) for the initiation of enzymatic attack. 55,98,99 In contrast, esterification using carboxylic acid reagents as used in the synthesis of DA-CNFs does not produce HCl at the site of functionalization, limiting damage to the cellulose chain, thereby producing DA-CNF samples with lower DS surface values, which undergo a smaller degree of biodegradation.…”

Impact of particle size reduction on high gravity enzymatic hydrolysis of steam-exploded wheat straw

“…Many studies impose that particle size reduction increases the accessibility between enzymes and cellulose, which results in improved glucan conversion [41]. For example, a recent modeling and simulation study from Gaikwad [42] investigated the effect of particle size dimensions of 0.78-25.52 µm on enzymatic hydrolysis of cotton cellulose. He stated that particle size reduction also increases the available reactive surface area for mass transfer actions, which favors enzyme adsorption and also reduces the probability of inhibition by lignin or hydrolysis products.…”

The role of the particle size reduction and morphological changes of solid substrate in the ultrasound-aided enzymatic hydrolysis of cellulose

“… [15] , [16] . Nevertheless, the effect of particle size on the enzymatic hydrolysis of cellulose is still contradictory in the scientific literature [17] , [18] , [19] , since the morphology, chemical composition, particle size of the original substrate, and the methods used for determining the size of particles (e.g. sieving, microscopy, laser diffraction, etc.)…”