Nanoscale Porous Materials for Water Treatment: Advances and Challenges - Nanotechnologies for Water Environment Applications - page 313

these materials, especially when they are used in nano-size, opened huge possibilities of
using NPM as sorbents for contaminants, catalysts, molecular sieves and in other related
applications (Clearfield, 1998). A number of excellent reviews have appeared in the
literature dealing with many aspects of different porous materials (Davis, 2002; Schüth
and Schmidt, 2002; Rolison, 2003; Savage and Diallo, 2005; Logar and Kaui, 2006).
Here, we focus on some of the most exciting developments on NPM, starting with a
section with types of the porous materials, followed by the discussion on some
developments in water treatment, and finally addressing its new application for in-situ
groundwater treatment and its challenges.
Table 11.1 Classification of porous materials based on pore-size.
Pore-
size
(nm)

Surface
Area
(m 2 /g)

Name Acronym Example Reference

Microporous
Materials*

(Savage and
Diallo, 2005)

< 2 MiPM Zeolites 1000

Mesoporous silica
e.g. MCM-41,
SBA-15 & HMS,
Mesoporous
alumina e.g. Al-
MCM-41

(Cooper and
Burch, 1999;
Kim et al.,
2004)

Mesoporous
Materials*

250 MePM 3071040

Macroporous
XAD-8 and
XAD-4 resins

(Duarte and
Duarte,
2005)

Macroporous
Materials*

> 50 MaPM 250750

NPM
(MiPM, MePM
& MaPM)

NZVI, Zeolite,
Mesoporous
Alumina/Silica

Nanoporous
Materials #

< 100 251200 This review

* Conventional nomenclature for porous materials. # Nomenclature in this review.

11.2. Nanoscale Porous Materials

As defined earlier, the NPM is such material which has its pore size less than 100
nm albeit its structure. Hence, this category itself covers a broad range of materials,
ranging from different organic to inorganic materials. Some of these materials have been
used from long time; many of them, however, have been recently introduced, and still
many are in their infancy stage. Since the nanoscale research boom in 1990s, importance
of these materials for environmental application has been realized more seriously;
exciting new developments has been taken place since then. Nanotechnology research
has been one of the central focuses of the United States Environmental Protection
Agency (USEPA). In this section, we try to cover this field by selecting those materials
that have been applied or will have great potential to be used in environmental areas.
Here, we categorized NPM into two broad subdivisions, i.e., inorganic NPM and carbon-