Effective Removal of Heavy Metals and Dyes from Drinking Water Utilizing Bio-compatible Magnetic Nanoparticle - Management of Natural Resources in a Changing Environment - page 117

Since the carboxyl (COO − ) of glycine residue electrostatically interacts with the
positively charged iron nanoparticle to form glutathione modifi ed iron nanoparticle,
the free end ( -glutamyl residue) of glutathione posses an amine group and a

carboxyl group among which the amine group nonspecifi cally interacts with
the negatively charged heavy metals forming a reversible electrostatic complex of
Cr-Glutathione-iron nanoparticle hybrid.
In order to study the effect of pH (basic and acidic) on adsorption behaviour,
glutathione fi ctionalized iron nanoparticle along with different concentration of
potassium dichromate have been taken together into different fl asks at pH 3 and
pH 11 separately (Fig. 4iia, b ). However, both pH 3 and 11 have shown to be the
better adsorption condition but at pH 3 the adsorption capacity increases sharply.
These results may be due to the fact that in the acidic pH, there is a competition
between the chromate and amine group.
In another experiment in this study, SDS modifi ed iron nanoparticle was
employed for adsorption of MG as described by Afkhami et al. ( 2010 ). The as-
synthesized amorphous nanoparticle which was developed in our laboratory by
a novel method was found to be very useful when coated with SDS for removal
of this dye. SDS being anionic surfactant will adsorb onto the surface of iron
nanoparticle through the negative moiety of sulfate (Li et al. 2008 ) and makes
the surface of the nanoparticle hydrophobic. The dye could be trapped into the
aggregates of SDS on iron nanoparticle (Hiraide et al. 1994 ). The effect of dif-
ferent amount of SDS modifi ed nanoparticle on the adsorption of MG was stud-
ied to determine the optimum amount for removal of MG in fl ask containing
1-2

ʳ

g/mL MG solution mixed with 200 ʼg/mL SDS coated nanoparticle at
pH 3. As Fig. 5 shows, the absorption of MG increased by increasing concentra-
tion of MG at constant adsorbent concentration. This result is consistent with

ʼ

Fig. 5 SDS functionalized magnetic nanoparticle mediated Malachite Green (dye) adsorption