Nanoscale Porous Materials for Water Treatment: Advances and Challenges - Nanotechnologies for Water Environment Applications - page 348

three fitted parameters ( Q 0 (maximum adsorption capacity, q (mg g -1 )), a , and
b(constants) ) of PMM depended on both PAH properties and the nature of carbon
nanomaterials. For different PAHs, adsorption seems to relate with their molecular size,
i.e., the larger the molecular size, the lower the adsorbed volume capacity ( Q 0 ), but
higher a and b values. For different carbon nanomaterials, adsorption seems to relate
with their surface area, micropore volume, and the volume ratios of mesopore to
micropore. Quantitative relationships between these sorbent properties and the estimated
parameters of PMM were obtained. These relationships represent the first fundamental
step toward establishing empirical equations for quantitative prediction of PAH
adsorption by carbon nanomaterials and possibly other forms of carbonaceous (geo-)
sorbents, and for evaluating their environmental impact (Yang et al., 2006). High
adsorption capacity of CNTs for a variety of contaminants may add to their high
environmental risks once released to the environment, and result in potential alteration
of contaminants fate and bioavailability in the environment. In this way, CNTs have
broadened their application beyond the use as a catalysts, redox material and adsorbents.
Figure 11.13 Schematic diagram of (a) SWNT and (b) MWNT. HRTEM image of (c)
SWNT and (d) MWNT.