en |
Preparation and characterization of gum karaya hydrogel nanocomposite flocculant for metal ions removal from mine effluents
Fosso-Kankeu, E.; Mittal, H.; Waanders, F.; Ntwampe, I.O. & Ray, S.S.
Abstract
This research paper reports the removal of
heavy metal ions from mine effluents using the gum karaya
(GK)-grafted poly(acrylamide-co-acrylic acid) incorporated
iron oxide magnetic nanoparticles (Fe3O4 MNPs)
hydrogel nanocomposite [i.e., GK-cl-P(AAm-co-AA)/
Fe3O4 hydrogel nanocomposite] and inorganic coagulants
such as polyferric chloride (af-PFCl), Al2(SO4)3, FeCl3 and
Mg(OH)2. The Fe3O4 MNPs were incorporated in the
matrix of the hydrogel polymer of Gk-cl-P(AAm-co-AA)
through the free radical graft co-polymerization technique
using N,N'-methylene-bis-acrylamide as the cross-linking
agent. The graft co-polymerization of the P(AAm-co-AA)
with Gk and the successful incorporation of the Fe3O4
MNPs within the hydrogel polymer matrix was evidenced
using different characterization techniques such as FTIR,
XRD, SEM and TEM. The performance of coagulants was
evaluated by considering parameters such as turbidity
removal, pH correction, metal removal and settling time. It
was observed that the monomeric inorganic coagulants had
a relatively poor performance compared to the organic
coagulant, i.e., GK-cl-P(AAm-co-AA)/Fe3O4 hydrogel
nanocomposite. Most of the coagulants achieved maximum
turbidity removal in the range of 67–99.5 %, but the
hydrogel nanocomposite showed the greatest reactivity by
achieving the fastest floc formation rate and shortest optimum
sedimentation time of 5 min (100 % removal in
5 min). The removal of metal followed the order
Pb2+ > Cr6+ > Ni2+ with an optimum settling time of
15 min; more often, Ni2+ was poorly removed (≤23.2 %
removal after 15 min) from acidic mine water samples.
Therefore, the synthesized hydrogel nanocomposite has
shown great potential as a flocculant and adsorbent for the
removal of suspended particles as well as heavy metal ions
and can be used to improve the quality of mine effluents
prior to discharge in the environment.
Keywords
Suspended particles; Heavy metal ions; Mine water; Inorganic and organic polymers; Flocculation
|