Diffusion coefficients of carbohydrates in modified κ-carrageenan gels with and without Escherichia coli immobilized

Brito, Edmundo; Juan, José Don; Domínguez, Fernándo; Casas, L.

doi:10.1016/0922-338x(90)90203-9

Cited by 18 publications

(5 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An alternative approach, proposed by Brito et al (1990) for galactose entrapped in modified K-carrageenan gel without cells, could also be extended to the present situation. Plotting lilD versus (l/T), according to a familiar Arrheniustype equation, they calculated an "activation energy" of 14.17 x lo3 J/mol for the diffusion process.…”

Section: 5mentioning

confidence: 99%

“…In particular, the results of Teixeira et al (1994) seem to demonstrate that, also when highly porous materials are used, glucose diffusivity is not significantly influenced by the support, while those of other metabolites, such as malic acid, are much more affected. On the other hand, different gels introduce an additional mass transfer resistance in the diffusion of several solutes, among which glucose and galactose (Furui and Yamashita, 1985;Brito et al, 1990).…”

mentioning

confidence: 99%

“…Unfortunately, because of the above drawbacks, the data available in the literature on glucose diffusivities are not sufficient to confirm the validity of the well-known equations of Wilke and Chang and Guzman and Andrade in the presence of cell aggregates. The equations were proposed in the past to relate diffusivity, viscosity, and temperature of non-electrolyte solutions at low concentrations (Wilke and Chang, 1955;Perry and Chilton, 1980) and subsequently were used in this field for diffusivity prediction only in the case of free diffusion in water (Brito et al, 1990;Beyenal and Tanyolaq, 1996;Hinson and Kocher, 1996). Notwithstanding the attempts of Karel et al (1985), Fan et al (1 990), and Beyenal and Tanyolaq (1996) to collect most of the available data, the operative conditions and the microbial systems used in the tests were too different.…”

mentioning

confidence: 99%

See 2 more Smart Citations

The effects of temperature and viscosity on glucose diffusivity through saccharomyces cerevisiae biofilms

et al. 1999

View full text Add to dashboard Cite

The present study helps us to understand the effects of temperature and viscosity on bioprocesses in immobilized cell bioreactors. Glucose diffusivities through Saccharomyces cerevisiae biofilms are experimentally investigated at variable biofilm thickness, temperature, and concentration of carboxymethylcellulose (CMC) used as viscosity-raising additive. Comparing these experimental values with those for free diffusion of glucose in water shows us that biofilm strongly reduces diffusivity (about 74%), mainly due to a decrease in the effective diffusion area. Only a slight increase in diffusivity is observed when biofilm thickness is increased. In addition, the results obtained in this work demonstrate that the well-known empirical equations of Wilke and Chang, and of Guzman and Andrade can be combined to a relationship which takes into account the simultaneous effects of temperature and viscosity on the effective glucose diffusivity. This equation appears to be valid in glucose aqueous solutions whether or not biofilm is used, whereas it is not applicable when viscosity-raising additives, such as CMC, are used.Le present travail nous aide a comprendre les effets de la temperature et de la viscosite sur les processus biologiques dans les reacteurs a cellules immobilisees. Les coefficients de diffusion du glucose a travers biofilms de Succharomyces cerevisiae sont determines experimentalement a epaisseur de biofilm, temperature et concentration de carboxymethylcellulose (CMC), employe comme additif de viscosite, variables. Une comparaison de ces valeurs avec celles obtenues pour la libre diffusion du glucose en eau montre que le biofilm reduit remarquablement la diffusivite (74% environ), a cause de la diminution de la superficie effective de diffusion. Seulement une augmentation minime de la diffusivite est observee quand I'epaisseur du biofilm est augmentee. En plus, les resultats obtenus dans ce travail montrent que les bien connus modeles de Wilke et Chang et de Guzman et Andrade peuvent &tre combines dans une relation qui tient compte des effets simultanes de la temperature et de la viscosite sur la diffisivite effective du glucose. Cette equation resulte &tre valide quant a solutions aqueuses de glucose soit en presence qu'en absence de biofilm, tandis qu'elle n'est pas applicable quand additifs de viscosite, comme la CMC, sont utilises.

show abstract

Section: 5mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

The effects of temperature and viscosity on glucose diffusivity through saccharomyces cerevisiae biofilms

et al. 1999

View full text Add to dashboard Cite

show abstract

“…Since diffusion in gels is affected by many factors which depend on experimental conditions and techniques used, diffusion coefficients reported in the literature have high variability making comparisons even for the same substrate difficult. Thus, experimentally determined diffusion coefficients for specific diffusing substrates and matrices are necessary for the analysis and design of reactors using immobilized cells (Brito et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Determination of diffusion coefficients and diffusion characteristics for chlorferon and diethylthiophosphate in Ca‐Alginate gel beads

Engler

Lee

2007

Biotech & Bioengineering

View full text Add to dashboard Cite

Diffusion characteristics of chlorferon and diethylthiophosphate (DETP) in Ca-alginate gel beads were studied to assist in designing and operating bioreactor systems. Diffusion coefficients for chlorferon and DETP in Ca-alginate gel beads determined at conditions suitable for biodegradation studies were 2.70 x 10(-11) m(2)/s and 4.28 x 10(-11) m(2)/s, respectively. Diffusivities of chlorferon and DETP were influenced by several factors, including viscosity of the bulk solution, agitation speed, and the concentrations of diffusing substrate and immobilized cells. Diffusion coefficients increased with increasing agitation speed, probably due to poor mixing at low speed and some attrition of beads at high speeds. Diffusion coefficients also increased with decreasing substrate concentration. Increased cell concentration in the gel beads caused lower diffusivity. Theoretical models to predict diffusivities as a function of cell weight fraction overestimated the effective diffusivities for both chlorferon and DETP, but linear relations between effective diffusivity and cell weight fraction were derived from experimental data. Calcium-alginate gel beads with radii of 1.65-1.70 mm used in this study were not subject to diffusional limitations: external mass transfer resistances were negligible based on Biot number calculations and effectiveness factors indicated that internal mass transfer resistance was negligible. Therefore, the degradation rates of chlorferon and DETP inside Ca-alginate gel beads were reaction-limited.

show abstract

“…An unsteady state model was developed to measure the effective substance diffusivity within an entrapment matrix used for whole cell immobilization [21,22]. Further studies investigated the effects of internal diffusion on the biodegradation rate of ferrous (II) cyanide complex (ferrocyanide) ions by Ca-alginate gel-immobilized P. fluorescens beads and reported that the diffusion characteristics for each combination of diffusing substrate and immobilized matrix are necessary to determine the diffusion coefficients for the analysis and design of reactors using immobilized cells [23,24]. Hence, to design, optimize and construct an efficient bioreactor for microorganism-immobilized catalyst systems, it is necessary to understand the internal mass transfer limitations.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of steady state and unsteady state mass transfer rate of Cr(VI) in immobilized Bacillus sp.

Kathiravan

Gim

Ryu

et al. 2015

Biotechnol Bioproc E

View full text Add to dashboard Cite

A novel hexavalent chromium (CrVI)-removing Bacillus sp. was isolated from leather industry wastewatercontaminated soil. This potential isolate was subjected to Cr(VI) removal under free and immobilized states in a stirred batch reactor (SBR). Two biokinetic parameters, V max and K m , and the effective diffusivity (D e ) for various bead sizes were calculated from Lineweaver-Burk and Eadie-Hoftsee plots, respectively. With respect to bead size, D e decreased significantly from a maximum of 3.024 × 10 −6 cm 2 /sec in the 0.20 cm bead to 2.948 × 10 −6 , 1.775 × 10 −7 , and 1.144 × 10 −7 cm 2 /sec in the 0.40-, 0.60-and 0.80 cm beads, respectively. Additionally, steady and unsteady state modeling of diffusional mass transfer into the immobilized beads was conducted to determine the mass transfer rate as a function of time and the beads' radial profile. Furthermore, the space-time yield (STY) was modeled according to the residence time of the reactor. The reactor's STY was reasonable and could be further boosted by increasing the fractional biocatalyst.

show abstract

Diffusion coefficients of carbohydrates in modified κ-carrageenan gels with and without Escherichia coli immobilized

Cited by 18 publications

References 9 publications

The effects of temperature and viscosity on glucose diffusivity through saccharomyces cerevisiae biofilms

The effects of temperature and viscosity on glucose diffusivity through saccharomyces cerevisiae biofilms

Determination of diffusion coefficients and diffusion characteristics for chlorferon and diethylthiophosphate in Ca‐Alginate gel beads

Evaluation of steady state and unsteady state mass transfer rate of Cr(VI) in immobilized Bacillus sp.

Contact Info

Product

Resources

About