Grafting
of guar gum (GG) and in situ strategic attachment of acrylamidosodiumpropanoate
(ASP) via solution polymerization of acrylamide (AM) and sodium acrylate
(SA) resulted in the synthesis of a sustainable GG-
g
-(AM-
co
-SA-
co
-ASP)/GGAMSAASP interpenetrating
polymer network (IPN)-based smart superadsorbent with excellent physicochemical
properties and reusability, through systematic optimization by response
surface methodology (RSM) for removal of methyl violet (MV) and/or
Hg(II). The relative effects of SA/AM ratios, in situ allocation of
ASP, grafting of GG into the AMSAASP terpolymer, ligand-selective
superadsorption mechanism, and relative microstructural changes in
individually/synergistically-adsorbed MV–/Hg(II)–/Hg(II)–MV–GGAMSAASPs
were determined by extensive analyses using Fourier transform infrared
(FTIR), proton nuclear magnetic resonance, ultraviolet–visible
(UV–vis), and O 1s-/N 1s-/C 1s-/Hg 4f
7/2,5/2
-X-ray
photoelectron spectroscopies, thermogravimetric analysis, differential
scanning calorimetry, X-ray diffraction, field emission scanning electron
microscopy, and energy-dispersive spectroscopy and were supported
by % gel content, pH
PZC
, and % graft ratio. The ionic/covalent-bonding,
monodentate, bidentate bridging, and bidentate chelating coordination
between GGAMSAASPs and Hg(II), and MV
+
–Hg(II) bonding
were rationalized by FTIR, UV–vis, fitment of kinetics data
to the pseudo-second-order model, and thermodynamic parameters. The
maximum adsorption capacities of 49.12 and 53.28 mg g
–1
were determined for Hg(II) and MV, respectively, under optimized
conditions.