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Membrane Processing for Dairy Ingredient Separation

  • Erscheinungsdatum: 18.06.2015
  • Verlag: Wiley-Blackwell
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Membrane Processing for Dairy Ingredient Separation

1 Microfiltration for casein and serum protein separation Kang Hu1, James M. Dickson1 and Sandra E. Kentish2 1 Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada, L8S 4L7 2 ARC Dairy Innovation Hub, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia 1.1 INTRODUCTION OF MICROFILTRATION Microfiltration(MF), probably the oldest membrane separation technology, was developed between the First and the Second World Wars in Germany for the purpose of bacteria removal (Zsigmondy and Bachmann, 1922). Generally, MF membranes have a pore size ranging from 0.1 to 10 µm. This size range encompasses a wide variety of natural and industrial particles, such as colloids, bacteria, and red blood cells. MF is a pressure-driven separation process, which is similar to other widely used membrane processes such as ultrafiltration, nanofiltration, and reverse osmosis. Compared to these processes, MF is typically operated at a relatively lower pressure and is mainly applied for larger particle separation and fractionation. In this section, the principle of MF is introduced. This includes the introduction of MF membranes and processes, the mechanism of cross-flow MF, and membrane fouling. 1.1.1 Microfiltration membranes and processes MF membranes can be synthesized from a wide variety of materials, normally categorized as either organic, such as polymers, or inorganic, such as ceramic materials. Polymeric materials can be hydrophobic, including polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF) and polypropylene (PP), or hydrophilic, including polycarbonate (PC) and poly(ethersulfone) (PES) (Mulder, 1996a). Ceramic membranes are typically made from alumina (Al2O3), zirconia (ZrO2), and titania (TiO2). During membrane fabrication, some hydrophobic materials can be surface-modified to become hydrophilic, as required by specific applications. Gekas and Hallstrom (1990) reviewed these materials and summarized both the advantages and disadvantages of them. They suggested that comparing the two materials, polymer membranes are generally less expensive and have a higher area/volume ratio than ceramic membranes. On the other hand, polymer membranes bind protein more readily and have a wider pore size distribution. Ceramic membranes have exceptional thermal and chemical resistance and a much longer membrane life. Various techniques have been employed to fabricate microporous membranes for MF. For example, ceramic membranes could be prepared by sintering layers on supporting materials. Polymeric membranes, benefiting from current polymer processing technology, could be prepared by various methods including: melt stretching, track etching, phase inversion, and casting (Glimenius, 1985; Mulder, 1996b). Depending upon the materials and techniques used to prepare the membranes, MF membrane pore structure varies significantly. Figure 1.1 illustrates some typical examples of membrane porous surface structures obtained with different fabrication methods and materials. From the images, membrane pores created by stretching (a) are not circular, but the manufacturing process is relatively simple. Pores created by track etching (b) are cylindrically shaped with uniform dimensions but with lower porosity, while pores created by phase inversion (c) have a much higher porosity (or pore density). For ceramic membranes, sintering results typically in a nodular structure (d). Figure 1.1 Microfiltration membrane surface images. (a) Polymeric membranes fabricated by melt-stretch (from Barbe, Hogan, and Johnson, 2000. Reproduced with permission of Elsevier). (b) Polymeric membranes fabricated by track-etching (Millipore Product Catalogue, 2013). (c): Polymeric membranes fabricated by phase in

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    Format: ePUB
    Kopierschutz: AdobeDRM
    Seitenzahl: 296
    Erscheinungsdatum: 18.06.2015
    Sprache: Englisch
    ISBN: 9781118590003
    Verlag: Wiley-Blackwell
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Membrane Processing for Dairy Ingredient Separation

1 Microfiltration for casein and serum protein separation

Kang Hu1, James M. Dickson1 and Sandra E. Kentish2

1 Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada, L8S 4L7

2 ARC Dairy Innovation Hub, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
1.1 INTRODUCTION OF MICROFILTRATION

Microfiltration(MF), probably the oldest membrane separation technology, was developed between the First and the Second World Wars in Germany for the purpose of bacteria removal (Zsigmondy and Bachmann, 1922). Generally, MF membranes have a pore size ranging from 0.1 to 10 µm. This size range encompasses a wide variety of natural and industrial particles, such as colloids, bacteria, and red blood cells.

MF is a pressure-driven separation process, which is similar to other widely used membrane processes such as ultrafiltration, nanofiltration, and reverse osmosis. Compared to these processes, MF is typically operated at a relatively lower pressure and is mainly applied for larger particle separation and fractionation.

In this section, the principle of MF is introduced. This includes the introduction of MF membranes and processes, the mechanism of cross-flow MF, and membrane fouling.
1.1.1 Microfiltration membranes and processes

MF membranes can be synthesized from a wide variety of materials, normally categorized as either organic, such as polymers, or inorganic, such as ceramic materials. Polymeric materials can be hydrophobic, including polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF) and polypropylene (PP), or hydrophilic, including polycarbonate (PC) and poly(ethersulfone) (PES) (Mulder, 1996a). Ceramic membranes are typically made from alumina (Al2O3), zirconia (ZrO2), and titania (TiO2). During membrane fabrication, some hydrophobic materials can be surface-modified to become hydrophilic, as required by specific applications. Gekas and Hallstrom (1990) reviewed these materials and summarized both the advantages and disadvantages of them. They suggested that comparing the two materials, polymer membranes are generally less expensive and have a higher area/volume ratio than ceramic membranes. On the other hand, polymer membranes bind protein more readily and have a wider pore size distribution. Ceramic membranes have exceptional thermal and chemical resistance and a much longer membrane life.

Various techniques have been employed to fabricate microporous membranes for MF. For example, ceramic membranes could be prepared by sintering layers on supporting materials. Polymeric membranes, benefiting from current polymer processing technology, could be prepared by various methods including: melt stretching, track etching, phase inversion, and casting (Glimenius, 1985; Mulder, 1996b).

Depending upon the materials and techniques used to prepare the membranes, MF membrane pore structure varies significantly. Figure 1.1 illustrates some typical examples of membrane porous surface structures obtained with different fabrication methods and materials. From the images, membrane pores created by stretching (a) are not circular, but the manufacturing process is relatively simple. Pores created by track etching (b) are cylindrically shaped with uniform dimensions but with lower porosity, while pores created by phase inversion (c) have a much higher porosity (or pore density). For ceramic membranes, sintering results typically in a nodular structure (d).

Figure 1.1 Microfiltration membrane surface images. (a) Polymeric membranes fabricated by melt-stretch (from Barbe, Hogan, and Johnson, 2000. Reproduced with permission of Elsevier). (b) Polymeric membranes fabricated by track-etching (Millipore Product Catalogue, 2013). (c): Polymeric membranes fabricated by phase in

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