Hexavalent
chromium
(Cr(VI))
contamination
in
soil
and
groundwater
is
usually
remediated
via
reduction
techniques.
The
formation
of
phosphate
(CrPO4)
occurs
as
a
byproduct
during
Cr(VI)
remediation
processes
the
presence
phosphate,
yet
its
stability
environment
has
received
limited
attention.
In
this
study,
conditions,
structure,
properties,
risks
associated
with
dissolution
oxidation
CrPO4
were
comprehensively
assessed.
Results
showed
that
crystalline
CrPO4·6H2O
was
formed
under
pH
5-7
at
room
temperature.
exhibits
higher
risk
compared
to
Cr(OH)3·3H2O
due
long
Cr-P
bond
(4.2
Å).
H+
OH–
increased
5
11,
respectively,
owing
CrH2PO42+
Cr(OH)4–.
addition,
faintly
acidic
high
solubility
increases
oxidation;
neutral
weakly
alkaline
positively
charged
Cr(H2O)63+
structures
on
surface
elevates
susceptibility
contact
by
δ-MnO2
Cr(OH)3·3H2O.
Specifically,
conversion
results
similar
for
both
Cr(III)
precipitates.
Environmental Science and Pollution Research,
Journal Year:
2024,
Volume and Issue:
31(5), P. 7977 - 7993
Published: Jan. 4, 2024
Abstract
In
this
study,
we
present
the
results
of
first
comparison
elimination
toxic
Cr(VI)
ions,
which
are
hazardous
contamination
environment,
from
aqueous
solutions
using
ion
exchangers
(IEs)
and
polymer
materials
(PMs)
impregnated
with
D2EHPA
or
ionic
liquids
(Cyphos
IL
101
Cyphos
104).
Sorption
ions
desorption
formulated
sorption
were
carried
out.
comparison,
classical
solvent
extraction
was
accomplished.
Fourier
transform
infrared-attenuated
total
reflectance
spectroscopy
(FTIR-ATR),
scanning
electron
microscopy-energy
dispersive
(SEM-EDS),
atomic
force
microscopy
(AFM)
have
been
used
for
characterization
structure
developed
IEs
PMs.
The
highest
efficiency
adsorption
obtained
PMs
(>82%).
Desorption
these
also
very
efficient
(>75%).
On
contrary,
application
allowed
obtaining
best
both,
processes
when
(75%
72%,
respectively).
is
part
green
chemistry,
conducted
chromium(VI)
allows
conclusion
that
they
can
potentially
be
on
a
larger
scale,
e.g.,
treatment
industrial
wastewater
rich
in
ions.
Ecotoxicology and Environmental Safety,
Journal Year:
2024,
Volume and Issue:
277, P. 116373 - 116373
Published: April 22, 2024
Cr
(VI)
is
extremely
harmful
to
both
the
environment
and
human
health,
it
can
linger
in
for
a
very
long
period.
In
this
research,
Leersia
hexandra
Swartz
constructed
wetland-microbial
fuel
cell
(CW-MFC)
system
was
purify
wastewater.
By
comparing
with
wetland
(CW)
system,
electricity
generation,
pollutants
removal,
enrichment,
morphological
transformation
of
were
discussed.
The
results
demonstrated
that
L.
CW-MFC
promoted
removal
production
system.
maximum
voltage
499
mV,
COD
efficiency
93.73%
97.00%.
At
same
time,
enhanced
substrate
ability
absorb
change
morphologically
transformation.
Additionally,
XPS
XANES
showed
majority
present
as
(III).
Geobacter
also
functioned
primary
metal
catabolic
reducing
electrogenic
bacteria.
As
result,
possesses
added
benefit
removing
while
producing
energy
compared
traditional
CW
Journal of Rock Mechanics and Geotechnical Engineering,
Journal Year:
2024,
Volume and Issue:
16(9), P. 3673 - 3695
Published: June 12, 2024
Due
to
climatic
factors
and
rapid
urbanization,
the
soil
in
Loess
Plateau,
China,
experiences
coupled
effects
of
dry-wet
cycles
chemical
contamination.
Understanding
mechanical
behavior
corresponding
microstructural
evolution
contaminated
loess
subjected
is
essential
elucidate
degradation
mechanism.
Therefore,
direct
shear
consolidation
tests
were
performed
investigate
variations
properties
compacted
with
acetic
acid,
sodium
hydroxide,
sulfate
during
cycles.
The
response
mechanisms
investigated
using
zeta
potential,
mineral
composition,
scanning
electron
microscopy
(SEM)
tests.
results
indicate
that
deterioration
hydroxide-contaminated
decreases
increasing
contaminant
concentration,
which
mainly
attributed
thickening
electrical
double
layer
(EDL)
by
Na+
precipitation
calcite,
as
well
formation
colloidal
flocs
induced
OH-,
thus
inhibiting
development
large
pores
process.
In
contrast,
attenuation
both
acid-
sulfate-contaminated
becomes
more
severe
latter
being
particularly
significant.
This
primarily
due
reduction
EDL
thickness
erosion
cement
acidic
environment,
facilitates
connectivity
Furthermore,
salt
expansion
generated
drying
process
saline
further
intensifies
structural
disturbance.
Consequently,
performance
sensitive
pollutant
type
exhibiting
different
patterns
cycling
condition.
Arabian Journal of Chemistry,
Journal Year:
2024,
Volume and Issue:
17(9), P. 105940 - 105940
Published: July 26, 2024
High-speed
steel
(HSS)
rolls
operate
in
harsh
conditions,
making
them
vulnerable
to
surface
degradation.
Material
removal
technology
for
repairing
defective
HSS
roll
surfaces
is
the
most
effective
way
maintain
their
integrity
and
reduce
production
costs.
Electrochemical
corrosion
machining,
with
its
excellent
machining
capabilities,
offers
a
promising
method
surfaces.
However,
outer
working
layer
of
these
made
premium
containing
passivating
metallic
elements,
complicating
behavior,
particularly
electrolytes.
To
elucidate
behavior
uncover
underlying
mechanisms
product
formation
during
electrochemical
this
study
investigates
process
M42
used
within
NaH2PO4-Na2SO4
electrolyte.
Metallographic
etching
experiments
indicated
that
comprises
tempered
martensitic
matrix
along
M2C
M6C
eutectic
carbides.
Characteristics
oxidative
reactions
electrolyte
were
observed
cyclic
voltammetry.
By
conducting
anodic
polarization
tests,
thermodynamic
analysis
characterization
techniques,
entire
electrode
system
was
thoroughly
examined,
including
phenomena,
varying
processes,
formation.
Notably,
first
construct
Pourbaix
diagram
HSS-H2PO4−-SO42−–H2O
system.
The
revealed
applied
potential
variation
significantly
influences
HSS,
confirming
by
results.
adsorption
phenomenon
on
cathodic
requires
higher
(such
as
6
V)
occur.
primarily
occur
surface,
while
(or
electrolyte)
mainly
engages
chemical
no
electronic
participation.
Furthermore,
driven
one
or
more
mechanisms,
such
galvanic
corrosion,
pitting,
intergranular
corrosion.
Therefore,
findings
from
contribute
development
based
future
engineering
applications.
