Mixing Effects in Cellulase-Mediated Hydrolysis of Cellulose for Bio-Ethanol Production

Chakraborty, Saikat; Aniket,; Gaikwad, Ashwin

doi:10.1021/ie100466h

Cited by 27 publications

(7 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, in the absence of complete data, we consider an equal probability of formation any chain i from any longer chain length j ( i < j ), and we use the term 2/( j – 1) in this model. The factor 2 accounts for the formation of the fractions j and ( i – j ), and the fractions ( i – j ) and j , from a chain length i . , …”

Section: Kinetic Modelmentioning

confidence: 99%

See 1 more Smart Citation

Multiscale Dynamics of Hemicellulose Hydrolysis for Biofuel Production

Dutta

Chakraborty

2019

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

Hemicelluloses are the earth's second most abundant structural polymers and are found in lignocellulosic biomass. This work uses a tightly coupled experimental and theoretical analysis to show that the enzymatic hydrolysis of hemicellulose is a two-phase multiscale reactive process, comprising the molecular scale, the pore scale, and the reactor scale. The pore scale is the smallest of these three scales, and the sequence of the length scales is given by reactor scale > molecular scale > pore scale. Enzyme adsorption to the solid xylan particles is the first important step in hemicellulose hydrolysis, followed by the cleaving of β-(1 → 4)-glycosidic bonds by an endoenzyme in solid and liquid phases. Our experiments show that enzyme adsorption and solid-phase hydrolysis primarily occur on the pore surface, with the former, though initially nonequilibrium, attaining equilibrium at 5 h. At the molecular scale, the products (xylose and xylobiose) inhibit the hydrolysis noncompetitively in both liquid-and solid-phase hydrolyses, and the nature of product inhibition remains unaltered by the mixing at the reactor scale. Model−experiment comparisons allow us to quantify the adsorption and desorption rate constants as well as the kinetic constants in the solid-and liquid-phase hydrolyses. The optimum solid loading is obtained as 5 mg/mL, above which substrate inhibition sets in. We develop an "optimal mixing" strategy comprising 55−70 min of initial reactor mixing followed by no mixing for the rest of the hydrolysis, which increases xylose and reducing sugar yields by 6.3−8% and 13−20%, respectively, over continuous mixing at 150 rpm for 1−5 mg/mL xylan, with an energy saving of 94−96% on reactor mixing over 24 h. We quantify the dominant phenomena and the determining timescales at each length scale, and we show that efficient depolymerization of solid carbohydrates results from coupled interscale interactions at various stages of the two-phase hydrolysis process.

show abstract

Section: Kinetic Modelmentioning

confidence: 99%

“…The factor 2 accounts for the formation of the fractions j and (i − j), and the fractions (i − j) and j, from a chain length i. 20,21 The rates of the formation of hemicelluloses of chain length i (i ≥ 12) in the solid phase are…”

mentioning

confidence: 99%

Multiscale Dynamics of Hemicellulose Hydrolysis for Biofuel Production

Dutta

Chakraborty

2019

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

show abstract

“…(Gaikwad and Chakraborty, 2013); what is the optimally mixed reactor configuration for enzymatic hydrolysis in continuous systems? (Chakraborty et al, 2010);(c) what is the optimal reactor mixing strategy for batch hydrolysis of cellulose? (Pal and Chakraborty, 2013);(d) what are the optimal mixing and temperature conditions for catalytic conversion of cellulose to biofuels in ionic liquid media?…”

Section: Introductionmentioning

confidence: 99%

A multiscale three-zone reactive mixing model for engineering a scale separation in enzymatic hydrolysis of cellulose

Chakraborty

Raju

Pal

2014

Bioresource Technology

Self Cite

View full text Add to dashboard Cite

“…In our previous work, we have discussed through model simulations how mixing limitations can offset inhibition, and increase yield as well as the rate of formation of desired product when the cellulose hydrolysis is performed in CSTRs. 32 We also suggested a novel reactor configuration of two CSTRs in series (with reasonable macromixing) with minimal local mixing/ micromixing in each tank and glucose removal at the exit of the first tank as the optimum reactor configuration for maximizing glucose yield. 32 We also performed modeling studies on cellulase-mediated hydrolysis of cellulose in batch reactors, in which enzyme diffusivity, two-site binding of the substrate, both solid and the soluble part of the substrate, degree of synergy between the enzymes, etc., were considered.…”

Section: ■ Introductionmentioning

confidence: 99%

“…32 We also suggested a novel reactor configuration of two CSTRs in series (with reasonable macromixing) with minimal local mixing/ micromixing in each tank and glucose removal at the exit of the first tank as the optimum reactor configuration for maximizing glucose yield. 32 We also performed modeling studies on cellulase-mediated hydrolysis of cellulose in batch reactors, in which enzyme diffusivity, two-site binding of the substrate, both solid and the soluble part of the substrate, degree of synergy between the enzymes, etc., were considered. 33 This article presents a tightly coupled experimental and theoretical study on the effect of mixing on Avicel hydrolysis in batch reactors.…”

Section: ■ Introductionmentioning

confidence: 99%

Mixing Effects on the Kinetics of Enzymatic Hydrolysis of Avicel for Batch Production of Cellulosic Ethanol

Gaikwad

Chakraborty

2013

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

This article presents a tightly coupled experimental and theoretical study to explore the effects of mixing and mass transfer on the kinetics and dynamics of cellulase-mediated cellulose (Avicel) hydrolysis for bioethanol production in batch reactors. The kinetic parameters (K M and V Max) for the three enzymes (endoglucanase, exoglucanase, β-glucosidase) that constitute cellulase are determined at various mixing speeds: 0 (no mixing), 40, 80, and 150 rpm (high mixing). The experimental values of K M and V Max are fitted to algebraic expressions that quantify them as functions of mixing speed, and that, in the asymptotic limit of complete mixing, give their purely kinetic values (without any mass transfer disguise). The glucose and reducing sugar yields as well as the degree of polymerization (DP) for Avicel are measured at all four mixing speeds for 45 h of incubation. Maximum yields of 76% for glucose and 87% for reducing sugar are obtained at no mixing condition (i.e., mass transfer controlled regime), and the DP was found to reduce from 300 to 41. An unsteady-state multistep three-enzyme kinetic model incorporating competitive and noncompetitive inhibition caused by the products glucose (monomer) and cellobiose (dimer) is simulated using the experimentally obtained K M and V Max values at various mixing speeds, and our model simulations are validated with our experiments. Our analysis shows that the K M and V Max for the three cellulase enzymes remain mass-transfer disguised kinetic parameters even at high mixing speeds, and we quantify the purely kinetic values they attain in the limit of perfect mixing. Our experiments and simulations show that lower mixing speeds increase glucose and reducing sugar yields and decrease DP by preventing the products glucose and cellobiose from coming in contact with the active sites of the cellulase, thus reducing product inhibition, an observation that may significantly reduce the energy costs for bioethanol production.

show abstract

Mixing Effects in Cellulase-Mediated Hydrolysis of Cellulose for Bio-Ethanol Production

Cited by 27 publications

References 17 publications

Multiscale Dynamics of Hemicellulose Hydrolysis for Biofuel Production

Multiscale Dynamics of Hemicellulose Hydrolysis for Biofuel Production

A multiscale three-zone reactive mixing model for engineering a scale separation in enzymatic hydrolysis of cellulose

Mixing Effects on the Kinetics of Enzymatic Hydrolysis of Avicel for Batch Production of Cellulosic Ethanol

Contact Info

Product

Resources

About