Enzyme Mass Transfer Coefficient in Aqueous Two Phase Systems: Spray Extraction Columns

Pawar, Prashant Ashok; Jafarabad, K. Rostami; Sawant, S.B.; Joshi, Jyeshtharaj B.

doi:10.1080/00986449308936154

Cited by 9 publications

(2 citation statements)

References 10 publications

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“…On the other hand, studies with spray columns in aqueous two-phase systems demonstrated an increase of the mass transfer coef®cient with VD increase, once the drop size at higher velocities is minor and produces high areas of mass transference [2,6,9,13,14].…”

Section: 2mentioning

confidence: 99%

Hydrodynamics and mass transfer in aqueous two-phase protein extraction using a continuous perforated rotating disc contactor

Porto

Sarubbo

Lima-Filho

et al. 2000

Bioprocess Engineering

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A continuous perforated rotating disc contactor was used to extract bovine serum albumin (BSA) with aqueous two-phase systems based on polyethylene glycol (PEG) and phosphate salts. The dispersed phase holdup and mass transfer coef®cient were determined. It was found that the dispersed phase holdup increased with increasing PEG phase velocity. The overall mass transfer coef®cient for BSA was independent of the PEG phase velocity.List of symbols C concentration of BSA in phosphate-rich phase (mg/ml) C u concentration of BSA in PEG-rich phase (mg/ml) C ui concentration of BSA in PEG-rich phase at the column inlet (mg/ml) C uo concentration of BSA in PEG-rich phase at the column outlet (mg/ml) H dispersed phase holdup K da mass transfer coef®cient (min )1 ) K partition coef®cient VD dispersed phase¯ow rate (ml/min) IntroductionAqueous two-phase (biphasic) systems have been extensively used for separation and analytical studies of biomaterials since Albertsson [1] developed the technique in the 1950s. Although similar in principle to conventional liquid-liquid extraction, aqueous two-phase extraction has uncommonly wide ranges of physical properties. For instance, the density difference between the two phases varies over the range 10±100 kg/m 3 , the interfacial tension over the range 10 )3 ±10 )2 mN/m, and the viscosities over the range 10±1000 mPa. Conventional liquid-liquid extraction has no property ranges of this magnitude [2]. It has been shown that conventional extraction techniques can be adequately applied to aqueous two-phase systems such as polymer-salt or polymer-polymer systems [1].Aqueous two-phase systems have an important potential in downstream processing such as continuous operation for the large-scale separation of biomolecules. A number of different conventional contactors, e.g. spray columns and packed columns, can be used for aqueous two-phase extraction [3]. Extraction columns with rotatory motion, namely a rotating disc contactor (RDC) and a perforated rotating disc contactor (PRDC), with free areā ow [4] have been used in industry as alternative apparatus to conventional separations equipment. With this type of extractor, high mass transfer rates between the phases were obtained to recover a recombinant cutinase from an aqueous solution to a reversed micellar phase of AOT in isooctane [5].For the design of commercial scale columns, data on the following parameters are needed: protein mass transfer coef®cients, dispersed phase holdup and the extent of mixing in both the phases. Usually, these parameters depend on the velocities of the two phases, their physical properties, the column diameter and the sparger design. In this work it is analyzed bovine serum albumin (BSA) mass transfer data from a laboratory perforated rotating disc contactor (PRDC) using the PEG-phosphates system. The BSA transfer took place from the PEG phase to the salt phase. Speci®cally, the dispersed phase holdup (H) is measured and the mass transfer coef®cients determined as well as the correlations for different disperse...

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Section: 2mentioning

confidence: 99%

Hydrodynamics and mass transfer in aqueous two-phase protein extraction using a continuous perforated rotating disc contactor

Porto

Sarubbo

Lima-Filho

et al. 2000

Bioprocess Engineering

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“…In the present work, the PEG−sodium sulfate−buffer (pH 5.7) system was used. The system compositions and their physical properties are given in Tables and , respectively. It can be seen from Table that, with an increase in the system composition, the interfacial tension, density difference, and the phase viscosities increase.…”

Section: Resultsmentioning

confidence: 99%

Lipoxygenase-1 Mass-Transfer Coefficient in Aqueous Two-Phase System Using Spray Extraction Column

Arsalani

Rostami

Kheirolomoom

2005

Ind. Eng. Chem. Res.

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Extraction of lipoxygenase-1 was investigated by using the aqueous two-phase system formed by sodium sulfate-poly(ethylene glycol)-buffer. The extraction was performed in a 47-mm inner diameter spray column, operating in a semibatch manner. The effects of dispersed-phase flow rate and phase compositions on fractional dispersed-phase hold up ( D ) and volumetric masstransfer coefficient (K D a) were respectively studied. It was found that the hold-up and volumetric mass-transfer coefficient increased with an increase in dispersed-phase velocity and decreased with increasing phase composition. Correlations have been developed by nonlinear regression for estimation of fractional dispersed-phase hold up and volumetric mass-transfer coefficients.

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Enzyme mass transfer coefficient in aqueous two‐phase systems: Modified spray extraction columns

et al. 1997

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The fractional dispersed phase hold-up and mass transfer coefficients were measured in modified spray columns of 50 mm i.d. using an aqueous two phase system of polyethylene glycol (PEG 4000)-sodium sulphate-buffer. The mass transfer coefficients were measured for amyloglucosidase and pgalactosidase. Both co-current and countercurrent modes of operation were investigated.The dispersed phase hold-up ( g o ) and the dispersed phase and the continuous phase mass transfer coefficients (kDa, k p ) increased with increasing dispersed phase velocity. An increase in the phase concentration of sodium sulphate and PEG was found to reduce E~, kDa, and k p . The performance of the modified spray column is compared with the conventional spray column. The modifications resulted into about a ten-fold enhancement in the throughput and about a five-fold reduction in the value of the height of a transfer unit (HTU or isolating a desired protein or an enzyme from a com-F plex mixture, the two-phase aqueous extraction technique offers the advantages of gentle environment, favourable processing time and easy scale-up (Albertsson, 1985).Methods of conventional extraction, such as spray columns, can be conveniently applied to aqueous two-phase systems. Spray columns are very popular because of their simple construction and ease of operation. Sawant et al. (1990) In these investigations, the maximum superficial velocity of the dispersed phase was 1.1 d s . Any W e r increase in the dispersed phase velocity led to the formation of a dense uncoalesced layer of drops in the top region of the liquid-liquid dispersion. This eventually resulted in the flooding of the spray column. The maximum permissible dispersed phase velocities are considerably lower than those possible for conventional liquid-liquid extraction systems using spray columns. This has resulted in relatively lower values of the mass transfer coefficient and the effective interfacial area. The HTU values estimated based on these prior results vary in the range of 3 to 5 m. Thus, a typical need of five theoretical stages will require considerably tall spray columns. From the foregoing discussion, it is clear *Author to whom correspondence should be addressed. E-mail address: j bj@udct .erne!. in that conventional spray columns need modification so that higher throughputs are possible and the values of HTU are well under 1 m.In addition to this, the data base with regard to mass transfer coefficients for proteins is limited. Protein molecules have a complex physical structure. Further, in comparison to the conventional solutes, the molar masses of proteins are very large (ranging from few to hundreds of thousands). The problem of mass transfer is further compounded by the higher viscosities of the two phases in aqueous two phase systems.The present paper addresses these problems. The spray column design is modified and the cross sectional area of the column in the coalescence zone is increased substantially to facilitate coalescence, thereby permitting the operation of the sp...

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Enzyme Mass Transfer Coefficient in Aqueous Two Phase Systems: Spray Extraction Columns

Cited by 9 publications

References 10 publications

Hydrodynamics and mass transfer in aqueous two-phase protein extraction using a continuous perforated rotating disc contactor

Hydrodynamics and mass transfer in aqueous two-phase protein extraction using a continuous perforated rotating disc contactor

Lipoxygenase-1 Mass-Transfer Coefficient in Aqueous Two-Phase System Using Spray Extraction Column

Enzyme mass transfer coefficient in aqueous two‐phase systems: Modified spray extraction columns

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