BASIC CONCEPTS AND AN OVERVIEW - Foundations of Nanotechnology: Pore Size in Carbon-Based Nano-Adsorbents - page 50

[108-120]. Activated carbon nano fibers (ACNFs) with large surface areas and
small pores were prepared by electros pinning and subsequent thermal and chemi-
cal treatments. These activated CNFs were examined as anodes for lithium-ion
batteries (UBs) without adding any non-active material. Their electrochemical
behavior show improved lithium-ion storage capability and better cyclic stability
compared with unactivated counterparts. The development of high-performance
rechargeable lithium ion batteries (LIBs) for efficient energy storage has become
one of the components in today's information rich mobile society [114].
Microbial fuel cell (MFC) technologies are an emerging approach to waste-
water treatment. MFCs are capable of recovering the potential energy present
in wastewater and converting it directly into electricity. Using MFCs may help
offset wastewater treatment plant operating costs and make advanced wastewater
treatment more affordable for both developing and industrialized nations. In spite
of the promise of MFCs, their use is limited by low power generation efficiency
and high cost. Some researchers conclude that the biggest challenge for MFC
power output lies in reactor design combining high surface area anodes with low
ohmic resistances and low cathode potential losses. Power density limitations are
typically addressed by the use of better-suited anodes, use of mediators, modifica-
tion to solution chemistry or changes to the overall system design. Employing a
suitable anode, however, is critical since it is the site of electron generation. An
appropriately designed anode is characterized by good conductivity, high specific
surface area, biocompatibility and chemical stability. Anodes currently in use are
often made of carbon and/or graphite. Some of these anodes include but are not
limited to: graphite plates/rods/felt, carbon fiber/cloth/foam/paper and reticulated
vitreous carbon (RVC). Carbon paper, cloth and foams are among the most com-
monly used anodes and their use in MFCs has been widely reported employ ac-
tivated carbon nanofibers (ACNF) as the novel anode material in MFC systems.
Compared with other activated carbon materials, the unique features of ACNF are
its mesoporous structure, excellent porous interconnectivity, and high bio avail-
able surface area for biofilm growth and electron transfer [115].
Among the diverse carbonaceous adsorbents, activated carbon fiber (ACF)
is considered to be the most promisingdue to their abundant micropores, large
surface area, and excellent adsorption capacity. Therefore, the investigation of
formaldehyde adsorption has been steadily conducted using ACFs. However,
most of precedent works have generally concerned about removal of concentrated
formaldehyde in aqueous solution (formalin, and thus there was limited informa-
tion whether these materials could be used in the practical application, because
the concentration of formaldehyde in indoor environment was generally very
low (below 1 ppm). The nitrogen containing functional groups in ACF played an
important role in increasing formaldehyde adsorption ability, as also described
elsewhere. However, the PAN-based ACFs still have problems in a practical ap-
plication, because the adsorption capability is drastically reduced under humid
condition [116, 120].