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Phenolic Wastewater Treatment: Development and Applications of New Adsorbent Materials 331
Sharma (2005) investigated the possible use of coal, residual coal, and residual
coal treated with H 3 PO 4 for removal of phenol from wastewater.
Biomasssuchasagriculturalsolidwastesandwastematerials,e.g.,sawdust,
rice husk, and bark, have been used as adsorbents. The role of sawdust mate-
rials in the removal of pollutants from aqueous solutions has been reviewed
recently (Shukla et al., 2002). Dutta et al. (2001) carried out studies on the
adsorption of p-nitrophenol on charred sawdust. The adsorption of phenol
on to sawdust, polymerized sawdust, and sawdust carbon was also studied
by Jadhav and Vanjara (2004). The potential of rice husk for phenol adsorp-
tion from aqueous solution was studied by Mahvi et al. (2004). Ahmaruzza-
man and Sharma (2005) also investigated the potential of rice husk and rice
husk char for the removal of phenolic compounds from wastewater.
Phenol removal has also been reported using industry waste such as fly
ash by Aksu and Yener (1999), and capacity was found to be 27.9 mg g 1
1
for fly ash and 108.0 mg g for granular AC. Application of bagasse fly
ash as a low-cost adsorbent for the removal of phenol and p-nitrophenol
has also been reported (Gupta et al., 1998; Mukherjee et al., 2007). A
detailed account of various low-cost adsorbents for the adsorption of phenols
was given in the review by Ahmaruzzaman (2008).
It is evident from the discussion above that a number of efficient adsor-
bents could be developed through judicious selection of raw precursors and/
or using different methods of activation. In this chapter, we further consol-
idate the existing knowledge base for synthesis, modification, and character-
ization of newer adsorbents and their applications in phenolic wastewater
treatment. The adsorbents that are reviewed belong to biomass-based sor-
bents, charred biomass, industrial waste, and synthetic adsorbents. New data
is provided on untreated forms of biomass-derived adsorbents such as banana
peel (BP) and tea waste (TW); modified adsorbents derived from egg shell;
and synthetic adsorbents from the class of binary mixed oxides.
All the materials derived from biomass that are reported here are available
in abundant quantities all over the world and attach specific significance for
developing countries such as India for utilization of such materials as adsor-
bents to tackle wastewater treatment problems. TW refers to tea fiber/stalks/
fluff or sweepings not including green tea or green tea stalks. The insoluble
cell walls of tea leaves are largely made up of cellulose and hemicelluloses,
lignin, condensed tannins, and structural proteins. Hence, due to the
presence of a number of functional groups, mainly carboxylate, aromatic
carboxylate, and phenolic hydroxyl groups, TW may be considered for
the adsorption of phenolic compounds from aqueous solutions. The yearly