Compression and heat treatment steps during the fabrication of
nanofibre adsorbents allow their physical properties to be tuned
towards their application as a chromatography medium. Mechanical
properties are critical for handling and packing into large
scale devices and impact operable flowrates, column capacity and
hence batch operation time. Functionalisations also directly affect
these bioseparation properties. The differences between DEAE
and COO modifications are clear as shown by changes in morphologies,
transbed pressures and capacities. Absorbent tensile
strengths were similar for DEAE and COO and were found to
increase with greater levels of compression after electrospinning
with no significant difference between functionalisations. Transbed
pressures show seemingly little effect between compressing
loads of DEAE and yet large changes for COO, which is attributed
to the hydrophilic COO groups. When studying protein separation
the highest attainable capacities by functionalisation were found
as a repeated treatment of 200 mmol/g adsorbent DAECH for DEAE
and 20 mmol/g NaClO for COO adsorbents. Nanofibres prepared at
the lowestlevel of compression (1 MPa) yielded the highest DBCs at
the lowest flowrate, which indicates the available surface area for
binding. At 5 and 10 MPa compressions capacity was decreased and
increasing bed layers compressed at 5 MPa also decreased DBCs.
However, DBCs recorded remained stable for increasing flowrate
at 5 and 10 MPa compressions while 1 MPa was only stable above
2000 CV/h.
This study shows that the interactions between fabrication and
functionalisation in the synthesis of nanofibre adsorbents are critical
to the required physical properties of the material for packing
and operating a bioseparation medium. This requires that nanofi-
bre materials properties are measured and understood alongside
developments in surface chemistry, in order to strike the correct
balance of capacity and material strength and tailor the material to
the application