title: Laccase-immobilized dendritic nanofibrous membranes as a novel approach towards the removal of bisphenol A.
abstract: Laccase enzymes from Rhus vernificera were covalently bound on hyperbranched polyethyleneimine/polyethersulfone (HPEI/PES) electrospun nanofibrous membranes and used for the removal of bisphenol A (BPA) from water. The laccase enzyme was anchored on the dendritic membranes through the abundant peripheral amine groups on the HPEI using glutaraldehyde as a crosslinker. The membranes were characterized with attenuated total reflectance-Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and ultraviolet-visible spectroscopy and correlative light and electron microscopy (CLEM). Furthermore, contact-angle analyses, pure water flux measurements and rejection analyses were carried out. CLEM showed that the enzymes were uniformly dispersed on the nanofibres while SEM analysis revealed that the nanofibres had an average diameter of 354 ± 37 nm. EDS showed the presence of Cu, which is the active entity in laccase enzymes. The laccase-modified membranes were hydrophilic (50°-53° contact angle) and exhibited high BPA rejection of 89.6% as compared to the 52.4% demonstrated by pristine PES. The laccase-modified membranes also maintained a constant permeate flux (7.07 ± 5.54 L/m2h) throughout the filtration process. Recyclability studies indicated that the membranes still maintained a high BPA removal of up to 79% even after four filtration cycles.
authors.affiliation: a Department of Applied Chemistry , University of Johannesburg , Johannesburg , South Africa.
authors.forename: Lebohang E
authors.initials: LE
authors.lastname: Koloti
authors.affiliation: b Department of Polymer Science , Stellenbosch University , Stellenbosch , South Africa.
authors.forename: Nonjabulo P
authors.initials: NP
authors.lastname: Gule
authors.affiliation: a Department of Applied Chemistry , University of Johannesburg , Johannesburg , South Africa.|c Centre for Nanomaterials Science Research , University of Johannesburg , Johannesburg , South Africa.
authors.forename: Omotayo A
authors.initials: OA
authors.lastname: Arotiba
authors.affiliation: a Department of Applied Chemistry , University of Johannesburg , Johannesburg , South Africa.
authors.forename: Soraya P
authors.initials: SP
authors.lastname: Malinga
mesh_terms: D001559:Benzhydryl Compounds / Q000032:analysis / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry; D008567:Membranes, Artificial; D057139:Nanofibers / Q000737:chemistry; D010636:Phenols / Q000032:analysis / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D042845:Laccase; D008567:Membranes, Artificial; D010636:Phenols; D014874:Water Pollutants, Chemical; C006780:bisphenol A; D000098826:Bisphenol A Compounds
keywords: Bisphenol A; electrospinning; hyperbranched polyethylenimine; laccase enzymes; nanofibrous membranes