Biomedical Engineering Reference
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were immobilized onto polymer matrices of chitosan in aqueous solutions contain-
ing Co(II) and/or Ni(II) ions were investigated (Repo et al., 2010). Metal uptake by
EDTA-chitosan was 63.0 mgg
−1
for Co(II) and 71.0 mgg
−1
for Ni(II) and by DTPA-
chitosan 49.1 mgg
−1
for Co(II) and 53.1 mgg
−1
for Ni(II). The adsorption efficiency
of the studied adsorbents ranged from 93.6% to 99.5% from 100 mgl
−1
Co(II) and/or
Ni(II) solution, when the adsorbent dose was 2 gl
−1
and solution pH 2.1. The kinetics
of Co(II) and Ni(II) on both of the modified chitosan followed the pseudo-second-
order model but the adsorption rate was influenced by intraparticle diffusion. The
equilibrium data was best described by the Sips isotherm and its extended form was
also well fitted to the two-component data obtained for systems containing different
ratios of Co(II) and Ni(II). Nevertheless, the obtained modeling results indicated rela-
tively homogenous system for Co(II) and heterogeneous system for Ni(II) adsorption.
The adsorption studies in two-component systems showed that the two new modified
chitosan had much better affinity for Ni(II) than for Co(II) suggesting that Ni(II) could
be adsorbed selectively from the contaminated water in the presence of Co(II).
Moreover, Katarina and coworkers (Katarina et al., 2008) have reported on a sample-
pretreatment method using a chitosan-based chelating resin, ethylenediamine-
N
,
N
,
N
'-
triacetate-type chitosan (EDTriA-type chitosan), for the preconcentration of trace met-
als in seawater and separation of the seawater matrix prior to their determination by
inductively coupled plasma-mass spectrometry (ICP-MS). According to those authors,
the resin showed very good adsorption for transition metals and rare-earth elements
without any interference from alkali and alkaline-earth metals in acidic media and that
the adsorption capacity of Cu(II) on the EDTriA-type chitosan resin was 0.12 mmol g
-1
of the resin. Additionally, Shimizu and colleagues (Shimizu et al., 2008) have prepared
chemically modified chitosans with a higher fatty acid glycidyl (CGCs) by the reaction
of chitosan with a mixture of 9-octadecenic acid glycidyl and 9,12-octadecanedienic
acid glycidyl (CG). The new chitosan modified polymer, CGC
s
was further modified
through the reaction with ethylenediamine tetraacetic acid dianhydride afforded CGCs
(EDTA-CGCs). The same researchers have studied the adsorption behavior of CGCs
towards the metal ions Mo
6+
, Cu
2+
, Fe
2+
, Fe
3+
, and found that Mo
6+
displayed remark-
able adsorption toward the CGCs. In addition, they examined the adsorption of Cu
2+
on
the ethylenediamine tetraacetic acid dianhydride modified CGCs (EDTA-CGCs) and
the adsorption of phosphate ions onto the resulting substrate/metal-ion complex was
measured. Similarly, Ni and Xu (1996) have synthesized a series of cross-linked chelat-
ing resins containing amino and mercapto groups, in addition to chitosan by reacting
chitosan with chloromethyl thiirane (CT) using different rations of chitosan to CT. The
adsorbing capacities, adsorption rates, and adsorption selectivities of these resins to-
wards Ag(I), Au(III), Pd(II), Pt(IV), Cu(II), Hg(II), and Zn(I1) were investigated. They
discovered that these chelating resins containing mercapto and amino groups have re-
markable adsorbing capacities and rates for some noble metal ions and can be used to
concentrate and retrieve precious metal ions from dilute solutions.
metal ion adsorption on Carbonyl Containing Chitosan derivatives
A new chitosan derivative was synthesized by the chemical modification of chitosan
(CTS) with vanillin-based complexing agent namely 4-hydroxy-3-methoxy-5-[(4-
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