11.2.2 Chemically Modified Carbonaceous Nanomaterials
The ability of carbonaceous cathodes to electrogenerate H 2 O 2 from the reaction in
Eq. 11.1 can be enhanced by chemically modifying their surface. Zhou et al. (2014)
modified a graphite felt (GF) with pure ethanol, yielding a material (GF-A) with
carbon nanoparticles of average diameter ca. 500 nm on the surface of the filaments.
A second kind of modification employing 90:10 (v/v) ethanol/hydrazine hydrate
mixtures yielded oxygen- and nitrogen-containing functional groups (GF-B),
resulting in weaker hydrophobicity compared with GF and GF-A, thus favoring
the H 2 O 2 generation. Its accumulation increased in the sequence: GF (67 mg/
L) < GF-A (110 mg/L) < GF-B (176 mg/L) upon electrolysis of 130 mL of an
O 2 -saturated 0.05 M Na 2 SO 4 solution at pH 3.0 using a three-electrode cell at
Table 11.1 Selected results obtained for the EF treatment of several organic pollutants using
undivided cells with cathodes based on graphene (Gr)
Cathode Substrate
Experimental remarks
Best performance
Ref.
Gr
Phenol
150 mL of 1 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode,
E cath ¼ À0.60 V/SCE
75% substrate decay
(180 min), 49% TOC
reduction (480 min)
Mousset
et al.
(2016b)
Methylene
Blue
100 mL of 11 mg/L dye in
0.1 mM Na 2 SO 4 , 11.1 mM Fe
2+ ,
pH 3.0, Pt anode,
E cath ¼ À1.0 V/SCE
100% color removal
(160 min)
Chen et al.
(2016a)
Gr/carbon felt
Acid
Orange 7
30 mL of 0.1 mM dye in 0.05 M
Na 2 SO 4 , 0.2 mM Fe
2+ , pH 3.0,
Pt anode, I ¼ 40 mA
94% TOC removal
(480 min)
Le et al.
(2015)
Orange II
100 mL of 50 mg/L dye in
0.05 M Na 2 SO 4 , 0.4 mM Fe
2+ ,
pH 3.0, DSA
® anode,
E cath ¼ À0.90 V/SCE
e
100% color and 79%
TOC decays
(60 min)
Yang et al.
(2017)
Gr/carbon
cloth
a
Phenol
80 mL of 1.4 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode, j ¼ 1.25 mA/
cm
2
92% substrate decay
(180 min), 57% TOC
reduction (480 min)
Mousset
et al.
(2016a)
Gr/carbon
cloth
(GDE)
b
Electronic
wastewater
400 mL of wastewater with
53.5 mg/L TOC, 0.2 mM Fe
2+ ,
pH 3.0, BDD anode. j ¼ 29 mA/
cm
2 f
92% TOC decay
(180 min)
GarciaRodriguez
et al.
(2018)
Gr/carbon
fiber
c
Phenol
400 mL of 0.33 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode, j ¼ 1.25 mA/
cm
2
99% substrate decay
(120 min), 98% TOC
reduction (360 min)
Mousset
et al.
(2017a)
Gr@graphite
d
Rhodamine
B
50 mL of 20 mg/L dye in 0.05 M
Na 2 SO 4 , 0.3 M Fe
2+ , pH 3.0,
DSA
® anode, j ¼ 20 mA/cm
2 e
100% color and 79%
COD decays
(60 min)
g
Zhang
et al.
(2018)
Cathode area:
a 15,
b
20,
c 126, and
d
1.5 cm
2
.
e DSA
®
—dimensionally stable anode.
f
BDD—borondoped diamond.
g
COD—chemical oxygen demand
262
I. Sirés and E. Brillas
The ability of carbonaceous cathodes to electrogenerate H 2 O 2 from the reaction in
Eq. 11.1 can be enhanced by chemically modifying their surface. Zhou et al. (2014)
modified a graphite felt (GF) with pure ethanol, yielding a material (GF-A) with
carbon nanoparticles of average diameter ca. 500 nm on the surface of the filaments.
A second kind of modification employing 90:10 (v/v) ethanol/hydrazine hydrate
mixtures yielded oxygen- and nitrogen-containing functional groups (GF-B),
resulting in weaker hydrophobicity compared with GF and GF-A, thus favoring
the H 2 O 2 generation. Its accumulation increased in the sequence: GF (67 mg/
L) < GF-A (110 mg/L) < GF-B (176 mg/L) upon electrolysis of 130 mL of an
O 2 -saturated 0.05 M Na 2 SO 4 solution at pH 3.0 using a three-electrode cell at
Table 11.1 Selected results obtained for the EF treatment of several organic pollutants using
undivided cells with cathodes based on graphene (Gr)
Cathode Substrate
Experimental remarks
Best performance
Ref.
Gr
Phenol
150 mL of 1 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode,
E cath ¼ À0.60 V/SCE
75% substrate decay
(180 min), 49% TOC
reduction (480 min)
Mousset
et al.
(2016b)
Methylene
Blue
100 mL of 11 mg/L dye in
0.1 mM Na 2 SO 4 , 11.1 mM Fe
2+ ,
pH 3.0, Pt anode,
E cath ¼ À1.0 V/SCE
100% color removal
(160 min)
Chen et al.
(2016a)
Gr/carbon felt
Acid
Orange 7
30 mL of 0.1 mM dye in 0.05 M
Na 2 SO 4 , 0.2 mM Fe
2+ , pH 3.0,
Pt anode, I ¼ 40 mA
94% TOC removal
(480 min)
Le et al.
(2015)
Orange II
100 mL of 50 mg/L dye in
0.05 M Na 2 SO 4 , 0.4 mM Fe
2+ ,
pH 3.0, DSA
® anode,
E cath ¼ À0.90 V/SCE
e
100% color and 79%
TOC decays
(60 min)
Yang et al.
(2017)
Gr/carbon
cloth
a
Phenol
80 mL of 1.4 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode, j ¼ 1.25 mA/
cm
2
92% substrate decay
(180 min), 57% TOC
reduction (480 min)
Mousset
et al.
(2016a)
Gr/carbon
cloth
(GDE)
b
Electronic
wastewater
400 mL of wastewater with
53.5 mg/L TOC, 0.2 mM Fe
2+ ,
pH 3.0, BDD anode. j ¼ 29 mA/
cm
2 f
92% TOC decay
(180 min)
GarciaRodriguez
et al.
(2018)
Gr/carbon
fiber
c
Phenol
400 mL of 0.33 mM substrate in
0.05 M K 2 SO 4 , 0.1 mM Fe
2+ ,
pH 3.0, Pt anode, j ¼ 1.25 mA/
cm
2
99% substrate decay
(120 min), 98% TOC
reduction (360 min)
Mousset
et al.
(2017a)
Gr@graphite
d
Rhodamine
B
50 mL of 20 mg/L dye in 0.05 M
Na 2 SO 4 , 0.3 M Fe
2+ , pH 3.0,
DSA
® anode, j ¼ 20 mA/cm
2 e
100% color and 79%
COD decays
(60 min)
g
Zhang
et al.
(2018)
Cathode area:
a 15,
b
20,
c 126, and
d
1.5 cm
2
.
e DSA
®
—dimensionally stable anode.
f
BDD—borondoped diamond.
g
COD—chemical oxygen demand
262
I. Sirés and E. Brillas