60 times of reuse for TiO 2 –sodium alginate and sodium alginate aerogels,
respectively.
Finally, the photocatalyticity of both aerogels was investigated by methyl orange
degradation under simulated sunlight. The methyl orange degradation rate was
constant during 150 min of irradiation. While in the presence of TiO 2 , the TiO 2 –
sodium alginate aerogel was stable against UV corrosion. All of these advantages
make the TiO 2 –sodium alginate aerogel appropriate for separating oil/water mixture.
Foams
Although the “sponge-like” and “foam-like” structures are frequently used interchangeably, there are many differences between them due to their actual physical
properties, ingredients, and molecular structure. A blowing agent (gas or chemical),
which can create multiple small bubbles, is needed to produce an air-filled matrix
structure from a liquid mixture. One of the most common foams used in oil/water
separation is foam rubber. Commercial foam rubbers are generally made of polymers. Three-dimensional porous structure, light weight, low raw material, good
mechanical properties, and excellent buoyant ability make them attractive for
oilsorption processes. Therefore, the improvement of the foam rubber has a significant effect on their oilsorption behavior. For instance, the ethylene propylene diene
monomer foam rubber was improved by trichloromethylsilane to produce a
superhydrophobic and superoleophilic sorbent (Liu and Kang 2018). The
trichloromethylsilane was used to generate hydrophobic layer on the ethylene
propylene diene monomer foam rubber through hydrolysis and polycondensation.
The as-prepared foam has lower surface energy and rougher surface than the
ethylene propylene diene monomer foam.
The contact angle measurement was used to prove the superhydrophobicity and
superoleophilicity of the improved foam. The water contact angle was 104.1
for
ethylene propylene diene monomer foam, while it was 159.3
for modified foam. To
demonstrate the superoleophilicity of the modified foam, a drop of hexane was
dropped on the foam, which permeated into it completely. In addition, the acidic,
neutral, and basic droplets were dropped on its surface that retained their spherical
shape, which indicates their non-wetting surface and their resistance in corrosive
environment. Moreover, the morphology analyses indicated that the surface of
modified foam with micro-nanometer pore size was rougher than that of the pristine
foam with millimeter pore size. In oilsorption experiments, organic solvents with
high and low viscosities were used with viscosity range of 0.326–409 mPa.s.
Figure 12.28 shows the oilsorption capacity of both foams for various organic
solvents.
The results showed that the oil uptake ability of ethylene propylene diene
monomer foam rubber was acceptable in low viscosity solvents. In addition, the
oil sorption decreased by increasing the oil viscosity due to the reduction of
wettability. While, the modified ethylene propylene diene monomer foam rubber
had an excellent oilsorption behavior for various oils and sorbed oils 8–12 times its
12 Remediation of Pollution by Oil Spills
433
respectively.
Finally, the photocatalyticity of both aerogels was investigated by methyl orange
degradation under simulated sunlight. The methyl orange degradation rate was
constant during 150 min of irradiation. While in the presence of TiO 2 , the TiO 2 –
sodium alginate aerogel was stable against UV corrosion. All of these advantages
make the TiO 2 –sodium alginate aerogel appropriate for separating oil/water mixture.
Foams
Although the “sponge-like” and “foam-like” structures are frequently used interchangeably, there are many differences between them due to their actual physical
properties, ingredients, and molecular structure. A blowing agent (gas or chemical),
which can create multiple small bubbles, is needed to produce an air-filled matrix
structure from a liquid mixture. One of the most common foams used in oil/water
separation is foam rubber. Commercial foam rubbers are generally made of polymers. Three-dimensional porous structure, light weight, low raw material, good
mechanical properties, and excellent buoyant ability make them attractive for
oilsorption processes. Therefore, the improvement of the foam rubber has a significant effect on their oilsorption behavior. For instance, the ethylene propylene diene
monomer foam rubber was improved by trichloromethylsilane to produce a
superhydrophobic and superoleophilic sorbent (Liu and Kang 2018). The
trichloromethylsilane was used to generate hydrophobic layer on the ethylene
propylene diene monomer foam rubber through hydrolysis and polycondensation.
The as-prepared foam has lower surface energy and rougher surface than the
ethylene propylene diene monomer foam.
The contact angle measurement was used to prove the superhydrophobicity and
superoleophilicity of the improved foam. The water contact angle was 104.1
for
ethylene propylene diene monomer foam, while it was 159.3
for modified foam. To
demonstrate the superoleophilicity of the modified foam, a drop of hexane was
dropped on the foam, which permeated into it completely. In addition, the acidic,
neutral, and basic droplets were dropped on its surface that retained their spherical
shape, which indicates their non-wetting surface and their resistance in corrosive
environment. Moreover, the morphology analyses indicated that the surface of
modified foam with micro-nanometer pore size was rougher than that of the pristine
foam with millimeter pore size. In oilsorption experiments, organic solvents with
high and low viscosities were used with viscosity range of 0.326–409 mPa.s.
Figure 12.28 shows the oilsorption capacity of both foams for various organic
solvents.
The results showed that the oil uptake ability of ethylene propylene diene
monomer foam rubber was acceptable in low viscosity solvents. In addition, the
oil sorption decreased by increasing the oil viscosity due to the reduction of
wettability. While, the modified ethylene propylene diene monomer foam rubber
had an excellent oilsorption behavior for various oils and sorbed oils 8–12 times its
12 Remediation of Pollution by Oil Spills
433