Field-Flow fractionation (FFF)

Technology
Technology details
Name:	Field-Flow fractionation
Category:
Feedstock:	Biowaste
Product:	Biomass in different physicochemical fractions

Field-Flow Fractionation (FFF) is a separation technology without a stationary phase for dilute suspensions. The suspensions can be fractionated according to their physicochemical properties such as charge, chemical composition, density, molar mass, and size. Beside analytical purposes the FFF can also be utilised for preparative purposes.

Feedstock

Origin and composition

Suitable feedstocks are heterogeneous mixtures of different substances in form of dilute suspensions (solids in liquid). Depending on the applied process and technology solids can be usually separated between the nm-µm range. The FFF is usually applied to separate cells, different kind of nanoparticles, polymers, and proteins for analytical and preparative purposes.

Pre-treatment

• Mechanical separations
  • Centrifugation
  • Membrane filtration
  • Particle classification, sieving
• Ultrasonication

Process and technologies

Different variants of the FFF are available including tha Asymmetric flow FFF, centrifugal FFF, electrical FFF, split flow thin-cell fractionation (SPLITT), and thermal FFF. Depending on the applied technology particles can be separated in dependence of different physicochemical properties.

Asymmetric flow FFF (AF4)

Illustration of a separation channel for asymmetric flow field-flow-fractionation.

Animation of the AF4 separation driven by particle diffusion in a parabolic flow profile. Particles colored in red are the smaller and particles colored in blue are the larger ones. The force applied on the top is the crossflow (indicated by the arrows on the bottom). The elution flow in longitudinal direction is shown with the flow arrows indicating the velocity profile.

The asymmetric flow FFF (AF4) is realised in a separation channel where an separation force ist generated in form of an asymmetric crossflow through a semipermeable membrane and frit. Through the cross-flow larger particles accumulate at the channel bottom while smaller particles accumulate more at the upper part induced by diffusion. The injected particles can be eluted through a parabolic flow-profile in combination with the reduction of the crossflow.

Centrifugal FFF

In centrifugal FFF the separation force is realised via an centrifugal field. Through the induced gravitational field larger particles accumulate at the channel bottom while smaller particles accumulate more at the upper part. The injected particles can be eluted through a parabolic flow-profile in combination with the reduction of the centrifugal field. Due to the large range of applicable centrifugal force the method has its advantage to separate a wide range of different sized particles (usually µm-nm range).

Electrical FFF

This technology combines the FFF with an electrical field as additional separation force. Besides the separation based on particle size this method adds the capability to separate particles/molecules in dependence of their charge.

Split flow thin-cell fractionation (SPLITT)

In Split flow thin-cell fractionation (SPLITT) earth's gravitational force is used to separate different sized particles (usually in µm-range). Usually the suspensions are introduced into the top of a separation channel while a carrier liquid is pumped into the channel from the bottom. The separation of different sized solids occurs along the channel induced by earth's gravity. Two outlets (one at the channel bottom, one at the channel top) at the end of the channel separates the particles into a larger and smaller fraction while the cut-off can be controllel via the channel flows.

Thermal FFF

Possibly not relevant

Technology providers

Technology comparison

Company name	Country	City	Technology category	Technology name	TRL	Capacity [kg/h]	Concentration (max.) [mg/mL]	Processable volume [L]	Separation range [µm]	Feedstock: Food waste	Feedstock: Garden & park waste	Separation according size	Separation according charge
Company 1	Germany	Cologne				9	0.00138	100	1-2	●	●	●	●
Company 2						9	0.003	0.5	0.5-100	●	●	●	●

Company 1

Field-Flow fractionation (FFF) provider

General information
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Technology and process details
Technology name:		Technology category:	Pre-processing (Separation technologies), Post-processing (Separation technologies)
TRL:		Capacity:	kg·h-1
Carrier solution:		Concentration (max.):	mg/mL
Processable volume:	L	Separation range:	µm
Temperature:	°C	Other:
Feedstock and product details
Feedstock:		Product:

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Company 2

Description of company 2