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Adsorption Parameters (adsorption + parameter)

Distribution by Scientific Domains

Life Sciences	50%
Chemistry	33%

Selected Abstracts

Kinetic modeling of cellulosic biomass to ethanol via simultaneous saccharification and fermentation: Part II.

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009
Experimental validation using waste paper sludge, anticipation of CFD analysis
Abstract A kinetic model of cellulosic biomass conversion to ethanol via simultaneous saccharification and fermentation (SSF) developed previously was validated experimentally using paper sludge as the substrate. Adsorption parameters were evaluated based on the data obtained at various values for fractional cellulose conversion. The adsorption model was then combined with batch SSF data to evaluate the cellulose hydrolysis parameters. With the parameters evaluated for the specific substrate, the discrete model was able to predict SSF successfully both with discrete addition of cellulase only and with discrete feeding of substrate, cellulase, and media. The model tested in this study extends the capability of previous SSF models to semi-continuous feeding configurations, and invites a mechanistic interpretation of the recently observed trend of increasing conversion with decreasing feeding frequency [Fan et al. (2007a) Bioprocess Biosyst Eng 30(1):27,34]. Our results also support the feasibility and utility of determining adsorption parameters based on data obtained at several conversions, particularly when the model is to be applied to extended reaction times rather than only initial hydrolysis rates. The revised model is considerably more computationally efficient than earlier models, and appears for many conditions to be within the capability of simulation using computational fluid dynamics. Biotechnol. Bioeng. 2009;102: 66,72. © 2008 Wiley Periodicals, Inc. [source]

Modeling and design of vapor-phase biofiltration for chlorinated volatile organic compounds

AICHE JOURNAL, Issue 9 2002
Walter Den
A mathematical model was developed for biofilter design and performance prediction with reference to the purification of contaminated gas streams. The model incorporated important aspects such as mass transfer, biodegradation, and adsorption processes. A systematic modeling protocol incorporated the development of a scale-up strategy based on dimensional analysis and similitude. Trichloroethylene (TCE) was employed as the model contaminant for biofiltration testing and model verification. The biokinetic and adsorption parameters for the contaminant were determined independently from a series of minibiofilter and miniadsorber column experiments, specifically designed to simulate the actual biofilter operational regimes in a miniature scale. Bench-scale biofilter experiments employing granular activated carbon columns indicated the good predictive capability of the model for the removal of TCE. Dynamic simulation studies were performed to assess the transient- and steady-state behavior of the model under various operating conditions. Model sensitivity was studied to evaluate the influence of adsorption equilibrium, transport and biological parameters on the biofilter dynamics. The results demonstrated that the biofilter performance was greatly influenced by the Monod coefficients and the biofilm thickness. [source]

Grafted Polymer Chains Interacting with Substrates: Computer Simulations and Scaling

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 9 2008
Radu Descas
Abstract We review scaling methods and computer simulations used in the study of the static and dynamic properties of polymer chains tethered to adsorbing surfaces under good solvent conditions. By varying both the grafting density and the monomer/surface interactions a variety of phases can form. In particular, for attractive interactions between the chains and the surface the classical mushroom-brush transition known for repulsive substrates splits up into an overlap transition and a saturation transition which enclose a region of semidilute surface states. At high grafting densities oversaturation effects and a transition to a brush state can occur. We emphasize the role of the critical adsorption parameters for a correct description and understanding of such polymer adsorption phenomena. [source]

Kinetic modeling of cellulosic biomass to ethanol via simultaneous saccharification and fermentation: Part II.

Access of cellulase to cellulose and lignin for poplar solids produced by leading pretreatment technologies

BIOTECHNOLOGY PROGRESS, Issue 3 2009
Rajeev Kumar
Abstract Adsorption of cellulase on solids resulting from pretreatment of poplar wood by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid (DA), flowthrough (FT), lime, and sulfur dioxide (SO2) and pure Avicel glucan was measured at 4°C, as were adsorption and desorption of cellulase and adsorption of ,-glucosidase for lignin left after enzymatic digestion of the solids from these pretreatments. From this, Langmuir adsorption parameters, cellulose accessibility to cellulase, and the effectiveness of cellulase adsorbed on poplar solids were estimated, and the effect of delignification on cellulase effectiveness was determined. Furthermore, Avicel hydrolysis inhibition by enzymatic and acid lignin of poplar solids was studied. Flowthrough pretreated solids showed the highest maximum cellulase adsorption capacity (,solids = 195 mg/g solid) followed by dilute acid (,solids = 170.0 mg/g solid) and lime pretreated solids (,solids = 150.8 mg/g solid), whereas controlled pH pretreated solids had the lowest (,solids = 56 mg/g solid). Lime pretreated solids also had the highest cellulose accessibility (,cellulose = 241 mg/g cellulose) followed by FT and DA. AFEX lignin had the lowest cellulase adsorption capacity (,lignin = 57 mg/g lignin) followed by dilute acid lignin (,lignin = 74 mg/g lignin). AFEX lignin also had the lowest ,-glucosidase capacity (,lignin = 66.6 mg/g lignin), while lignin from SO2 (,lignin = 320 mg/g lignin) followed by dilute acid had the highest (301 mg/g lignin). Furthermore, SO2 followed by dilute acid pretreated solids gave the highest cellulase effectiveness, but delignification enhanced cellulase effectiveness more for high pH than low pH pretreatments, suggesting that lignin impedes access of enzymes to xylan more than to glucan, which in turn affects glucan accessibility. In addition, lignin from enzymatic digestion of AFEX and dilute acid pretreated solids inhibited Avicel hydrolysis less than ARP and flowthrough lignin, whereas acid lignin from unpretreated poplar inhibited enzymes the most. Irreversible binding of cellulase to lignin varied with pretreatment type and desorption method. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]

Surface-Treated Activated Carbon for Removal of Aromatic Compounds from Water

CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 5 2009
B. Li
Abstract Modifications of commercial activated carbons by chemical treatment with HNO3 or HCl and HF and the adsorption behavior of simple aromatic compounds (aniline, pyridine, phenol, and benzene) on activated carbon and modified activated carbon were investigated. The results show that the textural properties change a little after these modifications, but the surface acidity (mainly oxygen-containing groups) of activated carbon modified with HNO3 increases greatly. The effect of ash of activated carbon on adsorption of the organic compounds mentioned above is insignificant. However, addition of surface acidity (mainly surface oxygen-containing groups) decreases the adsorption capacity of compounds significantly. The adsorption uptake of compounds on activated carbon with oxidation of HNO3 is low possibly due to dispersive interaction, water cluster blocking, or competition between water and compounds adsorbed on activated carbon's surface because of hydrophilic increase of the activated carbon surface. The solubility of aromatic compounds in water has an important effect on the adsorption capacity of activated carbon. qm and KL (Langmuir adsorption parameters) for the aromatic compounds vary similarly. [source]