125
5.5.4 Coconut Wastes
Coconut coir, pith, and its shell have average 21–26% cellulose, and its pretreatment
further increases the cellulose content. Coconut shell-based activated carbon was
attempted by researchers (Alaerts et al. 1989) for Cr(VI) removal, and the results
were compared with other activated carbons. Coconut husk fiber was used by Tan
et al. for Cr(VI) remotion in both batch and column processes. It was prepared by
boiling the grounded fiber with distilled water in steps: 1.5 M NaOH solution, distilled water, 2 M HNO 3 , and distilled water in order. Coconut husk fiber displayed
better removal at pH 2 (Tan et al. 1993). Another group of people used natural coconut husk for Cu(II) remediation and modified it with three different reactive dyes,
such as reactive yellow 2, acid blue 29, and acid blue 25, respectively. The dyecoated forms had more adsorption capacity, and the yellow two dye-coated coconut
husk yielded the maximum value. The process followed Langmuir equilibrium
model (Low et al. 1995). Baes et al. treated the coconut coir with sulfuric acid first
and then by 5% formaldehyde solution followed by HNO 3 and water and finally
dried at 100 °C and named as modified coconut coir. The modified coconut coir
could eliminate lead, copper, and nickel successfully, and they observed that the
adsorption capacity was highest at pH 6 and the sequential order was
Pb(II) > Cu(II) > Ni(II) (Baes et al. 1996). Manju and Anirudhan studied the performance of coconut pith fiber for Cr(VI) removal from aqueous solution. They
observed 99.2% Cr(VI) was removed at 2 pH for 50 ppm solution. Cr(VI) adsorption was not obstructed by the co-ions present. The spent adsorbent was reusable by
washing with alkali solution (Manju and Anirudhan 1997). Others observed that
coconut shell had high uptake (285.7 mg g
−1
) efficiency for Cd(II) at pH 7 over a
broad choices of concentrations (20–1000 mg L
−1
) and ion-exchange mechanism
followed (Pino et al. 2006). Table 5.6 depicts the q max values obtained by researchers.
5.5.5 Other Agricultural Wastes
Different parts of plants are rich in cellulose, and they have been used by scientists
for remediation of heavy metals since long. Dakiky et al. detoxicated Cr(VI) with
various wastes from agricultural origin and found their satisfactory removal efficiencies (Dakiky et al. 2002). Researchers (Dupont and Guillon 2003) used a lingo
cellulosic substrate prepared from wheat bran for Cr(VI) removal. They observed
large number of protons helped in reducing chromium from six oxidation state to
three, and concurrently lignin moieties were oxidized to form several hydroxyl and
carboxyl functional groups which contributed for ion exchange and displayed commendable performance. Others (Ozer et al. 2004; Ozer and Ozer 2004) used sulfuric
acid-treated wheat bran for Cu(II) and Cr(VI) removal and noted that the acid treatment increased the active surface area. A novel bioadsorbent was developed from
matured neem leaves by others for Cr(VI) and Cd(II) adsorption in batch process,
and around 87% metal was removed. They suggested high removal potentiality of
5 Cellulose-Based Adsorbents for Heavy Metal Removal
5.5.4 Coconut Wastes
Coconut coir, pith, and its shell have average 21–26% cellulose, and its pretreatment
further increases the cellulose content. Coconut shell-based activated carbon was
attempted by researchers (Alaerts et al. 1989) for Cr(VI) removal, and the results
were compared with other activated carbons. Coconut husk fiber was used by Tan
et al. for Cr(VI) remotion in both batch and column processes. It was prepared by
boiling the grounded fiber with distilled water in steps: 1.5 M NaOH solution, distilled water, 2 M HNO 3 , and distilled water in order. Coconut husk fiber displayed
better removal at pH 2 (Tan et al. 1993). Another group of people used natural coconut husk for Cu(II) remediation and modified it with three different reactive dyes,
such as reactive yellow 2, acid blue 29, and acid blue 25, respectively. The dyecoated forms had more adsorption capacity, and the yellow two dye-coated coconut
husk yielded the maximum value. The process followed Langmuir equilibrium
model (Low et al. 1995). Baes et al. treated the coconut coir with sulfuric acid first
and then by 5% formaldehyde solution followed by HNO 3 and water and finally
dried at 100 °C and named as modified coconut coir. The modified coconut coir
could eliminate lead, copper, and nickel successfully, and they observed that the
adsorption capacity was highest at pH 6 and the sequential order was
Pb(II) > Cu(II) > Ni(II) (Baes et al. 1996). Manju and Anirudhan studied the performance of coconut pith fiber for Cr(VI) removal from aqueous solution. They
observed 99.2% Cr(VI) was removed at 2 pH for 50 ppm solution. Cr(VI) adsorption was not obstructed by the co-ions present. The spent adsorbent was reusable by
washing with alkali solution (Manju and Anirudhan 1997). Others observed that
coconut shell had high uptake (285.7 mg g
−1
) efficiency for Cd(II) at pH 7 over a
broad choices of concentrations (20–1000 mg L
−1
) and ion-exchange mechanism
followed (Pino et al. 2006). Table 5.6 depicts the q max values obtained by researchers.
5.5.5 Other Agricultural Wastes
Different parts of plants are rich in cellulose, and they have been used by scientists
for remediation of heavy metals since long. Dakiky et al. detoxicated Cr(VI) with
various wastes from agricultural origin and found their satisfactory removal efficiencies (Dakiky et al. 2002). Researchers (Dupont and Guillon 2003) used a lingo
cellulosic substrate prepared from wheat bran for Cr(VI) removal. They observed
large number of protons helped in reducing chromium from six oxidation state to
three, and concurrently lignin moieties were oxidized to form several hydroxyl and
carboxyl functional groups which contributed for ion exchange and displayed commendable performance. Others (Ozer et al. 2004; Ozer and Ozer 2004) used sulfuric
acid-treated wheat bran for Cu(II) and Cr(VI) removal and noted that the acid treatment increased the active surface area. A novel bioadsorbent was developed from
matured neem leaves by others for Cr(VI) and Cd(II) adsorption in batch process,
and around 87% metal was removed. They suggested high removal potentiality of
5 Cellulose-Based Adsorbents for Heavy Metal Removal