Page 612 - Polymer-based Nanocomposites for Energy and Environmental Applications

Nanofibrous composite air filters 565

Fig. 20.11 PA-56 nanofiber-net membrane with filtration regeneration ability [21].

all, the solutions of PA-56 were prepared at varying concentrations (12, 15, 18, 21, and
24 wt%). Secondly, the PA-56 solution with a concentration of 18 wt% was mixed
with different weight ratios of HCOOH/CH 3 COOH (3:1, 1:1, and 1:3) [21]. As shown
in Fig. 20.11, PA-56 membrane with regeneration ability was used for filtration of
PM2.5. The QF of PA-56 with a concentration of 18 wt% was the best (0.0963).
According to the result of the filtration performance, PA-56 filter displayed tensile
strength of 11.02 MPa, excellent filtration efficiency of 99.995%, low pressure drop
2
of 111 Pa, high porosity of 81.35%, and great dust storage capacity of 49 g/m . Due to
the superior properties, PA-56 (3/1) can be used as an air filter in clean rooms, on
respirators, and within protective clothing [21].
Sim et al. [22] compared filtration properties of electrostatic (ES) filter and
nonelectrostatic (non-ES) (base) filter. Both filters coated Sophora flavescens
nanoparticles that are natural antimicrobial materials and coated using an aerosoliza-
tion process. Before antimicrobial treatment, ES and non-ES filters had nearly 51%
and 81% filtration efficiencies for KCl aerosols, respectively. It was observed that
S. flavescens nanoparticles were coated more effectively on ES filter compared
with non-ES filter (around 12% more areal density on ES filter). Though the filtration
efficiencies of both filters were affected significantly after antimicrobial treatment,
the filtration efficiencies of filters (ES and non-ES) for S. epidermis bioaerosols were
increased after antimicrobial treatment from 63% to 85% and from 84% to 89%,
respectively. This study showed that a hybrid air purification system can be used
in an indoor environment [22].
Zhoung et al. fabricated hybrid air filters with combining porous expanded poly-
tetrafluoroethylene membrane and ZnO nanorods. ZnO nanoparticles were deposited
on commercial ePTFE using atomic layer deposition, and then, ZnO nanorods were
grown on the seeding layer of the ZnO nanoparticles. After this modification, the
filtration efficiency increased from 96.11% to 99.99% for 300 nm particles. However,
the pressure drop slightly increased from to 0.31 to 0.36 kPa. Also, the hybrid air
filter showed antibacterial activity against both gram positive and negative bacteria
due to the presence of ZnO nanorods [23].