Environmental Engineering Reference
In-Depth Information
15.2.3
miscellaneous nanoadsorbents
cS-fe(0) NPs were prepared using biodegradable cS as a stabilizer, and batch experiments were conducted to evaluate the
influences of initial cr(VI) concentration and other factors on cr(VI) reduction on the surface of cS-fe(0) [45]. The authors
suggested that the overall disappearance of cr(VI) might include both physical adsorption of cr(VI) onto the cS-fe(0) surface
and subsequent reduction of cr(VI) to cr(III). characterization with high-resolution X-ray photoelectron spectroscopy revealed
that after the reaction, relative to cr(VI) and fe(0), cr(III) and fe(III) were the predominant species on the surface of cS-fe(0).
cS also inhibited the formation of fe(III)-cr(III) precipitation due to its high efficiency in chelating fe(III) ions. The adsorp-
tion of eosin Y, as a model anionic dye, from aqueous solution using cS NPs prepared by the ionic gelation between cS and
tripolyphosphate was examined by Du et al. [46] The adsorption capacity was found to be 3.33 g/g. The adsorption process
was endothermic in nature with an enthalpy change (ΔH) of 16.7 kJ/mol at 20-50°c. The optimum pH value for eosin Y
removal was found to be 2-6. The dye was desorbed from the cS NPs by increasing the pH of the solution. The desorption
percentage was about 60% within 60 min at pH 11.0, whereas 98.5% of the dye could be eluted at pH 12 in 150 min. The
potential of nanochitosan to remove acid dyes from aqueous solution was also explored by the researchers [47]. The mono-
layer adsorption capacities were determined to be 1.77, 4.33, 1.37, and 2.13 mmol/g nanochitosan for acid orange 10, acid
orange 12, acid red 18, and acid red 73 dyes, respectively. The differences in capacities might be due to the differences in the
particle size of dye molecules and the number of sulfonate groups on each dye molecule. The results have demonstrated that
monovalent and smaller dye molecular sizes have superior capacities due to the increase in dye/cS surface ratio in the system
and deeper penetration of dye molecules into the internal pore structure of nanochitosan. The mechanism of the adsorption
process of acid dye on nanochitosan was proposed to be the ionic interactions of the colored dye ions with the amino groups
on the cS. By encapsulating zirconium phosphate (ZrP) NPs into three macroporous polystyrene resins with various surface
groups, that is, −cH
2
cl, −SO
3
−
, and −cH
2
N
+
(cH
3
)
3
, three nanocomposite adsorbents (denoted as ZrP-cl, ZrP-S, and ZrP-N,
respectively) were fabricated for lead removal from water [32]. Effect of the functional groups on nano ZrP dispersion
and effect of ZrP immobilization on the mechanical strength of the resulting nanocomposites were investigated. charged
functional groups (−SO
3
−
and −cH
2
N
+
(cH
3
)
3
) are more favorable than the neutral −cH
2
cl group to improve nano ZrP
tAble 15.1
list of some nanoadsorbents used in the removal of different aquatic pollutants
Nanoadsorbent
Adsorbate
Uptake capacity
Reference
SWcNTs
Zn(II)
43.66 mg/g
lu and chiu [10]
MWcNTs
Zn(II)
32.68 mg/g
lu and chiu [10]
cS/cNT beads
congo red
423.1 mg/g
chatterjee et al. [14]
SWcNTs
Reactive red 120
426.49 mg/g
Bazrafshan et al. [15]
feOGel
cr(VI)
120 mg/g
Agrawal and Bajpai [33]
Magnetite nanoparticles
Methylene blue
70.4 mg/g
Giri et al. [37]
Magnetite nanoparticles
congo red
172.4 mg/g
Giri et al. [37]
Poly(γ-glutamic acid)-coated iron oxide
nanoparticles
Methylene blue
78.67 mg/g
Stephen and chen [38]
TiO
2
nanoparticles
Reactive red 195
87.0 mg/g
Belessi et al. [41]
chitosan nanoparticles
Eosin Y
3.33 g/g
Du et al. [46]
Nanochitosan
Acid orange 10
1.77 mmol/g
cheung et al. [47]
Nanochitosan
Acid orange 12
4.33 mmol/g
cheung et al. [47]
Nanochitosan
Acid red 18
1.37 mmol/g
cheung et al. [47]
Nanochitosan
Acid red 73
2.13 mmol/g
cheung et al. [47]
P(A-O)/AT nano-adsorbent
Pb(II)
109.9 mg/g
Jin et al. [48]
fe-Al-ce nanoadsorbent
(coated granules)
fluoride
2.77 mg/g
chen et al. [49]
Aligned carbon nanotubes
fluoride
4.5 mg/g
li et al. [61]
Nanoscale aluminum oxide hydroxide
fluoride
3259 mg/kg
Wang et al. [62]
caO nanoparticles
fluoride
163.3 mg/g
Patel et al. [63]
fe
3
O
4
@Al(OH)
3
NPs
fluoride
88.48 mg/g
Zhao et al. [64]
Nanoalumina
fluoride
14.0 mg/g
Kumar et al. [66]
Nanoalumina
Nitrate
4.0 mg/g
Bhatnagar et al. [65]
Nanoalumina
Bromate
6 mg/g
Bhatnagar and Sillanpää [67]
Mg-doped nano ferrihydrite
fluoride
64 mg/g
Mohapatra et al. [57]
Hierarchical porous ceO
2
nanospheres
congo red
942.7 mg/g
Ouyang et al. [56]
