Manufacturing and characterization of porous ceramic capillary membranes for enzyme functionalization through click chemistry

Porous zirconia capillaries were fabricated and characterized combining extrusion molding and sacrificial template technique. Colloidally stable ceramic paste made of two yttria-stabilized zirconia particle sizes, decane, hexane, stearic acid and beeswax was prepared and extruded, leading to different porosities. To confer mechanical stability to the capillaries, a thermal treatment was conducted at 1438 K. The surface of the ceramic microtubes was functionalized in order to promote click chemistry and immobilize acetylene functionalized enzymes on it. Furthermore, introducing a hydrothermal activation on the ceramic surface had a beneficial effect on further deposition of APTES. The open porosity of the samples ranged from 50 to 56% and water permeate flux from 140 up to 388 L/(m2 h bar). Characteristic flexural strength up to 76 MPa was recorded for the samples with the blend of the zirconia powders. Moreover, a trend could be observed, decreasing the zirconia particle size enhanced the mechanical strength of the sintered bodies. On the other hand, the intrinsic permeability has decreased. Regarding enzyme activity, capillaries with larger zirconia particle size led to better enzyme activity results. Porous zirconia capillaries show a promising future for immobilized enzyme applications under flow regime.