The particle diameter of the water bamboo husk sorbents prepared
in this study ranged from 45 to 250 μm. The BET measurement gave a
pore size distribution of 5.7–13.8 nm for these particles, which is close
to that of Ponkan mandarin peel particles (3–13 nm) [12] but slightly
larger than banana peel particles (1.05 nm) [10]. The specific surface
area of water bamboo husk particles, also determined by BET,
was found to be 1.87 m2/g. This result is near those for banana peel
(2 m2/g) [10] and Pu-erh tea powder (40 mesh, 1.71 m2/g) [18]. Nevertheless,
it is much smaller than that reported for Ponkan mandarin
peel (119.3 m2/g) [12] and much larger than pine cone powders
(0.0993 m2/g (raw pine cone) and 0.122 m2/g (acid-treated pine
cone)) [19]. The pore size and surface area of biosorbents vary with
the agricultural material adopted. Water bamboo husk provides the
properties similar to most of the plant wastes studied in the literature.
To identify the functional groups on water bamboo husk particles,
their FTIR spectrum was recorded and the result is presented in Fig. 2.
The spectrum is very similar to the results of other biosorbents. The
broad band at 3420 cm−1 wasmainly ascribed to the OH group, whereas
the band at 2920 cm−1 was assigned to the aliphatic CH groups
[2,10–12,18–21].Moreover, the peaks at 1710 and 1640 cm−1 were attributed
to the CO bond of carboxylic acids [2,10–12,18–21]. The above
FTIR results indicate that water bamboo husk particles contain OH and
COOH groups. Accordingly, positively-charged heavy metal ions would
be able to bind with these active groups under appropriate pH conditions,
via charge interaction, and adsorbed onto the water bamboo
husk particles