Environmental Engineering Reference
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added drop-wise to an Fe(SO 4 )•7H 2 O (Alfa Aesar) methanol (BDH, supplied by VWR,
West Chester, PA, USA)/water solution, resulting in a suspension of black iron particles.
The iron particles were subsequently vacuum-filtered and washed with ethanol to
remove excess borohydride. The iron particles were then vacuum-dried at 120°C under
the nitrogen environment. After drying, the particles were passivated by allowing air to
slowly bleed over them for 12 h. Fine nZVI powders were obtained by grinding the
resulting black iron clusters. The nZVI powder was stored in a glovebox (Innovative
Technology Inc., Newburryport, MA, USA) under the nitrogen environment.
Characterization of the modified nZVI was done using transmission electron
microscopy (TEM, JEOL JEM-100CX II, JEOL Ltd., Tokyo, Japan) . A concentrated
nZVI sample was prepared in ethanol, sonicated, and placed on a Formvar ® -coated
copper grid (300 mesh) for analysis at an accelerating voltage of 80 kV. X-ray
diffraction (XRD) of the modified nZVI was conducted using a Philips X'Pert MPD with
Cu K X-ray source. Analyses were carried out at 40 kV and 30 mA with a scan range
from 20 to 80. The Brunauer-Emmett-Teller (BET, ASAP 2000, Micromeritics,
Norcross, GA, USA) specific surface area of the synthesized nZVI was determined by
N 2 gas absorption.
Synthesis and Characterization of APGCs. APGCs were synthesized using
PtO 2 -catalyzed hydrosilylation. The reaction scheme involving commercially-available
hydride-functional polysiloxanes and commercially-available monofunctional vinyl
compounds is shown in Figure 8.3 .
O
O
O
O
Si
Si
Si
Si
+
+
PtO 2
PtO 2
R
R
H 3 C
H 3 C
CH 3
CH 3
H
H
R
R
Figure
8.3
Hydrosilylation
between
hydride-functional
polysiloxanes
and
monofunctional vinyl compounds .
The following is a procedure used to produce a representative APGC: 10 g of a
poly(methylhydrosiloxane-dimethylsiloxane) copolymer containing 3.98 mM of hydride
groups per g of polymer (HMS 151, Gelest), 10.2 mM of monoallyl-functional
polyethyleneglycol (PEG, Clariant), and 10.2 mM of tert -butylacrylate (tBA, Aldrich)
were dissolved in toluene. A catalytic amount of PtO 2 (Aldrich, St. Louis, MO, USA)
was added, and the mixture was heated at 90°C overnight. Upon completion of the
reaction, the reaction mixture was cooled to room temperature, platinum oxide removed
by vacuum filtration, and the polymer isolated by vacuum stripping the toluene.
To generate the carboxylic acid anchoring groups, the tert -butyl ester groups of
the graft copolymer were hydrolyzed as follows: 2.0 g of the polymer was dissolved in 5
 
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