(7.07 Æ 5.54 L/m
2 h) throughout the filtration process. Polyacrylonitrile/montmorillonite/graphene oxide composite nanofibers were evaluated by Wang et al.
(2014a) in a homemade nanofibrous membrane reactor. These membranes with
immobilized laccase from Trametes versicolor were successfully applied for the
removal of catechol from an aqueous solution. The addition of graphene oxide in the
nanomembrane composite significantly improved its operational and storage stability. The treatment method was simple, low cost, and produced no secondary
pollution, making it a good candidate for future industrial and remediation applications. Four types of electrospun fibrous membranes with laccase catalytic activity
were fabricated by emulsion electrospinning by Dai et al. (2013). The membranes
were employed in biocatalytic membrane reactor for removal of polycyclic aromatic
hydrocarbons from water. The rapid adsorption of polycyclic aromatic hydrocarbons
onto the membranes significantly improved their degradation efficiencies by a
laccase.
A few attempts were made to remediate real contaminated samples. Ba et al.
(2014) prepared laccase and tyrosinase cross-linked enzyme aggregates. In batch
mode, the aggregates transformed more than 80% to nearly 100% of acetaminophen
from municipal wastewater and more than 90% from hospital wastewater. ArcaRamos et al. (2016) treated secondary effluent of municipal wastewater by laccase
immobilized onto fumed silica nanoparticles. Compared to soluble laccases,
immobilized enzymes led to much slower rates of bisphenol A transformation. For
instance, after 24 h the percentages of bisphenol A removal by free laccases or
immobilized enzymes reached 67.8 Æ 5.2 and 27.0 Æ 3.9%, respectively. The
transformation of diclofenac could not be achieved with the tested biocatalysts
under real municipal wastewater conditions. Dai et al. (2011) investigated laccasecarrying electrospun nanofibrous membranes for adsorption and degradation of
polycyclic aromatic hydrocarbons in shoal soils. The removal efficiencies for phenanthrene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene after 6 h were
greater than 95.1%, 93.2%, 79.1%, and 72.5%, respectively. Saranya et al. (2014)
treated wastewater from oil refinery using lipase immobilized on functionalized
nanoporous activated carbon. The immobilized lipase showed high efficiency for
the hydrolysis of oil in batch and continuous mode and high operational stability of
up to 50 cycles of use. The authors concluded that the prepared biocatalysts have
great potential for remediation of lipid-containing wastewater from the industrial
sectors. Yuan et al. (2016) introduced novel magnetic molecularly imprinted
immobilized cellulases. The biocatalysts were used for the effective degradation of
fruit and vegetable waste and for synergistic recovery of anthocyanins.
Recently published papers demonstrated good stability and performance of newly
synthetized biocatalytic nanocomposites and nanomembranes. However, the efficiency of the nanostructures was mainly tested in pure water or buffer solutions. It is
obvious from the few studies mentioned above that real matrix has a significant
impact on the efficiency of these bioremediation processes. Further studies are
essential to evaluating the feasibility of utilizing such biocatalytic nanocomposite
systems in real contaminated matrices. Another weakness of the works performed so
far is the scale of the tested processes. Almost all experiments using hybrid
16 Enzyme-Based Nanomaterials in Bioremediation
361
2 h) throughout the filtration process. Polyacrylonitrile/montmorillonite/graphene oxide composite nanofibers were evaluated by Wang et al.
(2014a) in a homemade nanofibrous membrane reactor. These membranes with
immobilized laccase from Trametes versicolor were successfully applied for the
removal of catechol from an aqueous solution. The addition of graphene oxide in the
nanomembrane composite significantly improved its operational and storage stability. The treatment method was simple, low cost, and produced no secondary
pollution, making it a good candidate for future industrial and remediation applications. Four types of electrospun fibrous membranes with laccase catalytic activity
were fabricated by emulsion electrospinning by Dai et al. (2013). The membranes
were employed in biocatalytic membrane reactor for removal of polycyclic aromatic
hydrocarbons from water. The rapid adsorption of polycyclic aromatic hydrocarbons
onto the membranes significantly improved their degradation efficiencies by a
laccase.
A few attempts were made to remediate real contaminated samples. Ba et al.
(2014) prepared laccase and tyrosinase cross-linked enzyme aggregates. In batch
mode, the aggregates transformed more than 80% to nearly 100% of acetaminophen
from municipal wastewater and more than 90% from hospital wastewater. ArcaRamos et al. (2016) treated secondary effluent of municipal wastewater by laccase
immobilized onto fumed silica nanoparticles. Compared to soluble laccases,
immobilized enzymes led to much slower rates of bisphenol A transformation. For
instance, after 24 h the percentages of bisphenol A removal by free laccases or
immobilized enzymes reached 67.8 Æ 5.2 and 27.0 Æ 3.9%, respectively. The
transformation of diclofenac could not be achieved with the tested biocatalysts
under real municipal wastewater conditions. Dai et al. (2011) investigated laccasecarrying electrospun nanofibrous membranes for adsorption and degradation of
polycyclic aromatic hydrocarbons in shoal soils. The removal efficiencies for phenanthrene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene after 6 h were
greater than 95.1%, 93.2%, 79.1%, and 72.5%, respectively. Saranya et al. (2014)
treated wastewater from oil refinery using lipase immobilized on functionalized
nanoporous activated carbon. The immobilized lipase showed high efficiency for
the hydrolysis of oil in batch and continuous mode and high operational stability of
up to 50 cycles of use. The authors concluded that the prepared biocatalysts have
great potential for remediation of lipid-containing wastewater from the industrial
sectors. Yuan et al. (2016) introduced novel magnetic molecularly imprinted
immobilized cellulases. The biocatalysts were used for the effective degradation of
fruit and vegetable waste and for synergistic recovery of anthocyanins.
Recently published papers demonstrated good stability and performance of newly
synthetized biocatalytic nanocomposites and nanomembranes. However, the efficiency of the nanostructures was mainly tested in pure water or buffer solutions. It is
obvious from the few studies mentioned above that real matrix has a significant
impact on the efficiency of these bioremediation processes. Further studies are
essential to evaluating the feasibility of utilizing such biocatalytic nanocomposite
systems in real contaminated matrices. Another weakness of the works performed so
far is the scale of the tested processes. Almost all experiments using hybrid
16 Enzyme-Based Nanomaterials in Bioremediation
361