Bio-catalytic degradation of recalcitrant micropollutants with enzymes such as laccase provides an
environmentally attractive alternative to the conventional filtration and adsorption processes. However,
enzyme loss and denaturation remain key challenges for their potential use in water treatment
applications. In this work, laccase immobilization on TiO2 nanoparticles and TiO2 blended polyethersulfone
(PES) membranes were investigated due to TiO2's chemical stability, ease of functionalization,
and architecture. Different surface modification and functionalization strategies on support materials
were compared based on enzyme loading, apparent activity, activity recovery, and stability. When
coupling agent 3-aminopropyltriethoxysilane (APTES) and cross-linker glutaraldehyde (GLU) were
applied sequentially, effective coupling of laccase was achieved based on 2,2′-azino-bis-(3-ethyl
benzothiazoline-6-sulfonic acid) (ABTS) assays. TiO2 functionalized PES membrane showed better
enzyme immobilization efficiency than the non-functionalized membrane. Optimal performance was
observed for PES membrane containing 4 wt% TiO2, where TiO2 not only provided the enzyme coupling
sites but also affected the membrane surface morphology and hydrophilicity to favor the enzyme
immobilization. These bio-catalytic membranes also displayed good enzyme stability, tolerance to wider
pH range and vigorous filtration conditions required for water treatment applications. Kinetic study also
indicated that the enzyme affinity to assay substrate was maintained after immobilization when
compared with packed bed and batch reactors.